Diseases of lymphatic system

Diseases of lymphatic system by Dr. Rashmi Burlakoti

1. Lymphatic system and related diseases Dr.Rashmi Burlakoti FCPS Resident, Bir Hospital,NAMS

2. Lymphatic system consists of the lymphatic vessels and lymph nodes through which lymph and immune cells traffic to establish and maintain immune responses. There are lymphatics in most of the body tissues except brain,spinal cord,bone marrow, splenic pulp and articular cartilages .

3. Function of lymphatic system 1)provides an important pathway for drainage of fluid from cells and tissues back to the bloodstream 2)It is a vital part of the immune system.

4. Lymph nodes They are encapsulated aggregates of lymphatic tissues,normally small and bean shaped. Situated in the path of lymphatic vessels 600 in number Covered by fibrous capsule Consists of hilum through which the blood vessels enter and leave the lymph node. Contains central medulla and peripheral cortex.

5. Lymphatic drainage of head and neck Approximately 300 lymph nodes are present in adult neck, loos.ely arranged into several groups

6. Level I: submental and submandibular below  mylohyoid muscle  and above the lower margin of the hyoid bone (or the carotid bifurcation) anterior to the posterior border of the  submandibular glands level Ia :   submental nodes level Ib :   submandibular nodes

7. Level II: upper internal jugular (deep cervical) chain base of the skull to the inferior border of hyoid bone (or the carotid bifurcation) anterior to the posterior border of  sternocleidomastoid (SCM) muscle posterior to the posterior border of the submandibular glands level IIa :  inseparable from or anterior to the posterior edge of the internal jugular vein most superior node is the jugulodigastric node level IIb :  posterior to the internal jugular vein and have a fat plane separating the nodes and the vein

8. Level III: middle internal jugular (deep cervical) chain inferior margin of hyoid to inferior margin of  cricoid cartilage anterior to the posterior border of SCM lateral to the medial margin of the common carotid artery (CCA) / internal carotid artery(ICA )

9. Level IV: lower internal jugular (deep cervical) chain inferior margin of cricoid cartilage to level of the clavicle anterior and medial to an oblique line drawn through the posterior edge of SCM and the posterolateral edge of the anterior scalene muscle lateral to the medial margin of the CCA

10. Level V: posterior triangle (spinal accessory) posterior to the posterior edge of the  sternocleidomastoid muscle and anterior to the anterior border of the  trapezius muscle  level Va :  superior half, posterior to levels II and III (between base of the skull and inferior border of cricoid cartilage) level Vb :  inferior half, posterior to level IV (between the inferior border of cricoid cartilage and the level of clavicles)

11. Level VI: anterior compartment, prelaryngeal , pre- and paratracheal from the inferior margin of hyoid bone to the  manubrium anterior to levels III and IV includes the  Delphian node and nodes in the visceral space Level VII: (anterior) superior mediastinal from suprasternal notch to innominate artery technically outside the neck but still considered regional lymph nodes.

12. Most deep structures drain to jugulodigastric lymph node. The drainage is into nodes in lower neck, often called the lymph nodes of virchow or trosier,that drain into the venous system directly or via the thoracic duct or right lymphatic duct. The superficial and anterior neck structure may drain into the anterior,superficial cervical (external jugular) nodal groups including pretracheal,prelaryngeal and paratracheal nodal chains.

13. Size dependant criteria most nodes should be <10 mm in short-axis except: submental / submandibular and jugulodiagastric : <15 mm retropharyngeal: <8 mm if using size criteria alone then there is a 10-20% error rate The long-to-short axis ratio of >2 (i.e. long and flat) 95% are benign. When the ratio <2 (i.e. rounder) then a similar proportion were malignant . Size independent criteria loss of fatty hilum focal necrosis cystic necrotic node s

14. Lymphatic drainage of the thorax

15. Supraclavicular zone Station 1 (left/right): low cervical, supraclavicular , and sternal notch nodes Extends from cricoid cartilage to thoracic inlet. left and right are divided by the mid-line of the trachea station 1 nodes are  outside  the mediastinum and staged as an N3 disease; despite this, they can sometimes be treated with radical intent if they are encompassable in a radiotherapy field

16. Upper zone (superior mediastinal nodes) Station 2 (left/right): upper paratracheal nodes superior border: thoracic inlet  left (2L) and right (2R) are divided along the left lateral border of the trachea, not the midline inferior border of 2R: at the intersection of caudal margin of the left  brachiocephalic vein with the trachea inferior border of 2L: superior border of the aortic arch

17. Station 3A & 3P: pre-vascular and retrotracheal nodes superior border: thoracic inlet inferior border: carina 3A: prevascular - anterior to the great vessels (superior vena cava on the right, left common carotid artery on the left), posterior to the sternum 3P: retrotracheal - posterior to the trachea

18. Station 4 (left/right): lower paratracheal nodes left (4L) and right (4R) are divided along the left lateral border of the trachea,   not the mid-line 4R: superior border: intersection of caudal margin of the left brachiocephalic vein with the trachea inferior border: inferior border of the  azygos vein 4L superior border: superior border of the aortic arch inferior border: superior border of the left main pulmonary artery pre- carinal nodes lymph nodes anterior to the tracheal bifurcation part of the 4R/4L stations 

19. Aortopulmonary zone Station 5: subaortic nodes ( aortopulmonary window) lateral to  ligamentum arteriosum superior border: inferior border of the aortic arch inferior border: superior border of the left main pulmonary artery Station 6: para -aortic nodes, ascending aorta or phrenic anterior and lateral to the ascending aorta and aortic arch superior border: line tangential to the upper border of the aortic arch inferior border: lower border of the aortic arch

20. Subcarinal zone Station 7: subcarinal nodes superior border: carina inferior border - left:   upper   border of the lower lobe bronchus inferior border - right: lower   border of  bronchus intermedius

21. Lower zone (inferior mediastinal nodes) Station 8 (left/right): para-oesophageal nodes (below carina) superior border: station 7, i.e. upper border of lower lobe bronchus on left, and lower border of bronchus intermedius on right inferior border:  diaphragm Station 9 (left/right): pulmonary ligament nodes lying within the pulmonary ligament superior border: inferior pulmonary vein inferior border: diaphragm

22. Hilar and interlobar zone (pulmonary nodes) Station 10 (left/right): hilar nodes immediately adjacent to mainstem bronchus and hilar vessels superior border: lower border of the azygos vein on the right, the upper border of the pulmonary artery on the left Station 11: interlobar nodes between the origin of the lobar bronchi

23. Peripheral zone (pulmonary nodes) Station 12: lobar nodes adjacent to lobar bronchi Station 13: segmental nodes adjacent to segmental bronchi Station 14: sub-segmental nodes adjacent to subsegmental bronchi

24. Lymphatic drainage of the abdomen and pelvis Lymph from inguinal nodes drain into external ilac nodal chain. The external, internal iliac and obturator lymph nodes drain the pelvic viscera into the retroperitoneal nodes. Abdominal viscera drain into the mesenteric lymphnodes . Either a single or two mesenteric lymphatic trunks may be observed. The mesenteric lymphatic vessels, which are very small, unite to form the intestinal trunk, which enters the cisterna chyli .

25. The cisterna chyli receives the two lumbar lymphatic trunks, right and left, and the intestinal lymphatic trunk. The cisterna chyli is a saccular area of dilatation of the lymphatic channels that originates at the L1–L2 level of the vertebral body and extends 5–7 cm in the caudocephalad direction. It is located in the retrocrural space, usually to the immediate right of the abdominal aorta. The cisterna chyli continues in the cephalic direction as a thoracic duct that enters the thorax through the aortic hiatus of the diaphragm and terminates at the junction of the left subclavian and internal jugular veins, draining lymph into the venous circulation

26. Imaging the lymphatic system

27. Lymphography Sensitive test that studies the lymphatic ducts and the internal architecture of nodes. Occassionally demonstrate micrometastases in normal sized lymph nodes and can be used for follow up maging of nodal diseases as the contrast persist in lymphnode for 6-12 months. It examines only lymphnodes and ducts in the drainage pathway from the legs and arms.

28. lymphatic contrast needs to be introduced in the periphery and will only highlight the lymphatic vessels draining that position. To identify a lymphatic vessel for cannulation , oily contrast agent is injected into the dermis where it is absorbed by initial lymphatics and fills the lymphatic vessels that drain the injection site. This allows identification of lymphatic channels that can then be cannulated and injected with an opaque contrast agent for radiographic imaging. Radiography taken both immediately after the procedure,to demonstrate the lymphatics and again after at least 24 hrs delay to demonstrate the lymph node.

29. Lymphoscintigraphy Indications: Investigation of the primary lymphoedemas To study the major drainage nodes for tumors(sentinel nodes/mapping) Tc-radiolabelled serum albumin is used which outline the drainage lymphatics and nodes. It can then be imaged using a scintillation camera to produce a 2D image of the lymphatic network. It can be performed at any site as it doesn’t rely on cannulating the lymphatic duct.

30. Ultrasound US can be useful in investigating nodal masses and as an aid to FNAC/ biopsy. Endoscopic US can provide high resolution imaging to detect locoregional lymphadenopathy in oesophageal,pancreatic and rectal carcinoma. Limited view in mediastinum,retroperitoneum and deep pelvis.

31. CT and MRI CT is generally the method of choice, providing a direct and reproducible demonstration of normal and abnormal lymphnodes . Radiation dose issue make MRI a potentially important option in the follow up of nodal disease.

32. Lymph node enlargement is the imaging hallmark of metastatic involvement and a series of size criteria for normal and abnormal lymph nodes have evolved in the different areas of the body . Enlargement of the lymph nodes above this criterion is suggestive but not diagnostic of malignant involvement. The images should always be interpreted in the light of the clinical findings and the known behaviour of the particular tumour . Contrast images helps in better characterisation .

33. Specific lymph node contrast media are being developed for MRI including the ultra small supraparamagnetic iron oxides (USPIO) in MRI. USPIOs are opsonised by normal lymph nodes reducing their normal high signal on T2 The poor spatial resolution and sensitivity are limitations of MRL

34. Magnetic resonance lymphography (MRL) It provides high contrast and good spatial resolution in soft tissues such as the lymphatic system. Ultrasmall super-paramagnetic iron oxide (USPIO, <50 nm) is a common contrast agent that decreases relaxation times in lymph nodes. This results in the focal, non-enhancing regions in lymph nodes with metastases The technique is relatively non-invasive and can be used to identify anatomic and physiological abnormalities associated with lymphatic dysfunction in order to determine further treatment strategies

35.  Coronal 3D MR lymphography image of the lower extremities obtained after subcutaneous injection of contrast material. Abnormal, dilated lymphatic vessels extend from the left calf to the inner thigh (small arrows). Some lymphatic vessels in the contralateral normal limb appear discontinuous (small arrows). Veins appear as linear structures with lower intensity (large arrows) 

36. Radionuclide Techniques Circulating radionuclides may be taken up by metastatic lymph nodes. This is best recognised with gallium-67. The sensitivity of the test to the presence of active lymphoma tissue is related to the volume of the tumour , the location injected , the dose and the instrumentation . Gallium-67 imaging is sensitive to the presence of lymphoma in patients but has proved less effective than CT in determining the extent of disease site by site within individual patients. At present the clinical role of gallium-67 scanning in lymphoma is best limited to the follow-up of patients with initial positive scans.

37. Positron emission tomography usage of positron emission tomography (PET) is for lymph node imaging using the glucose analogue 18-FDG. This detects increased metabolism in tumour -bearing nodes and is therefore potentially more sensitive and specific than CT. Furthermore PET images can be superimposed on CT images to give anatomical and metabolic information together.

38. PET may prove even more useful in the follow-up of disease where it may distinguish recurrent disease from reactive or residual scarring in enlarged lymph nodes . PET however does not specifically image malignancy but increase in metabolism, and there is therefore scope for false-positive results. Also it is still not capable of excluding the microscopic tumour involvement that histology can show . It is therefore a complimentary technique at increased cost that can be very useful in certain cases.

39. DISORDERS OF THE LYMPHATIC DUCTS lymphoedemas can be divided into primary and Secondary . The primary type may be further subdivided into congenital, praecox (before the age of 35 years) and tarda (after the age of 35 years). On the basis of the lymphographic appearances aplasias with no demonstrable lymphatics , the hypoplasias with a reduced number of lymphatics , and the hyperplasias with an increase in the number of lymphatics present.

40. Primary lymphoedema vascular dysplasia often associated with arterial and venous malformations in the same limb and other congenital defects . Most patients have aplasia or severe hypoplasia of the lymphatics . The oedema may be precipitated by minor trauma or surgery. Peak incidence is seen in girls at puberty and typically involves the left leg. The term Milroy's disease is loosely applied to primary lymphoedema . CT assessment of the size and number of the lymph nodes can objectively classify patients into aplasia , hypoplasia and hyperplasia of the lymphatic system.

41. Secondary lymphoedema This is more common than primary lymphoedema , and indicates the presence of obstruction to the normal forward passage of lymph. may be due to previous surgery or irradiation, from recurrent tumour . Uncommon causes : infection, especially with filariasis . CT is the most useful investigation , especially when looking for new or recurrent tumour .

42. Disorders of the lymph nodes Malignant involvement of a lymph node typically results in the enlargement of the affected lymph node. This may be considered to involve four stages: 1) the deposition of a malignant cell within the lymph node and subsequent cell division, resulting in the presence of a micrometastasis within the affected lymph node. At this stage the lymph node remains of normal size and shape and will appear normal on CT and MRI examination. A CT density measurement is required to differentiate a small metastasis within a lymph node from a focal deposit of fat . In the neck the incidence of fibrofatty foci within normal-sized lymph nodes is less than in the abdominal, pelvic and axillary lymph nodes, making this a valid technique.

43. 2) an involved lymph node will enlarge and become recognisable clinically and/or with cross-sectional imaging. 3) the outline of the tumour becomes blurred due to the presence of tumour extending into the perinodal tissues 4) malignant spread of tumour to a lymph node results in a large amorphous tumour mass with infiltration of the tissue planes. At this time it is impossible to identify any residual nodal outline.

44. Benign conditions affecting the LNs Acute inflammation will enlarge lymph nodes. On lymphograms the texture of the lymph node will become more foamy, an appearance usually associated with lymphoma. G ranulomatous or abscess-forming inflammations produce filling defects in the lymph nodes similar to those seen in secondary deposits. Lymph nodes may be seen to enlarge in a number of granulomatous diseases , including sarcoid and tuberculosis.

45. Reactive hyperplasia usually associated with a proliferation of histiocytes cause of lymph node enlargement. This may be related to recent surgery Reactive enlargement of lymph nodes is a possible source of error if patients are scanned too close to the date of their surgery. It is better to wait 3-4 weeks.

46. Fibrofatty deposits are seen within the lymph nodes of older patients , and these are most commonly seen in the pelvis. They maybe considered a normal finding in the inguinal region, but in the remainder of the pelvis they are a source of confusion, as they may be incorrectly interpreted as secondary deposits in patients with a primary pelvic neoplasm.

47. Malignant conditions involving the LNs Tumours spread by three mechanisms: local invasion, lymph node and haematogenous spread . The mechanism of spread depends on the particular tumour subtype and location. Malignant neoplasms may metastasise at the subclinical level. The detection of metastatic lymph nodes is an important component of tumour staging and is always a poor prognostic indicator and may change management.

48. LYMPHOMAS primary neoplasms of the immune system and arise within lymphoid tissue Lymphomas commonly present as enlargement of one or groups of lymph nodes causing painless rubbery lumps under the skin. Disease can also present in extranodal lymphatic tissue and mimic a multitude of other diseases in these tissues Has variable manifestations and prognosis. The histological subtype and the anatomical extent of disease at the time of diagnosis have prognostic significance

49. Hodgkins disease A ccounts for approximately 25% of newly diagnosed lymphomas   Bimodal distribution: peaks in young adults (15-34 years) and older patients (>55 years ). Male>Female Typical presentation : painless lymphadenopathy , systemic symptoms (B symptoms) such as night sweats,fever and weight loss C haracterised by the presence of  Reed-Sternberg cells  Contiguous spread is another feature. EBV infection is present in 40-80% depending on subtype 

50. Subtypes There are five recognised histological subtypes . Classical nodular sclerosing : ≈70% mixed cellularity : ≈25% lymphocyte-rich: 5% lymphocyte depleted: <5 % Non-classical nodular lymphocyte predominant (nodular paragranuloma )

51. Lymphocyte Predominant form Present with a localised disease, often with palpable supraclavicular lymph nodes. Most frequently seen in young asymptomatic males. On histologic review of the excised lymph nodes, the characteristic Reed–Sternberg cells are scanty. H as an excellent prognosis, and may be treated with local rather than systemic therapy .

52. Lymphocyte depleted form Usually polysymptomatic , and on investigation will be found to have advanced disseminated disease. Histological review of excised lymph nodes will show numerous Reed–Sternberg cells. The prognosis is very poor.

53. Mixed cellularity most frequently seen histopathological subtypes . It may be seen in every age group, but is especially frequent in young adults . Patients with MC disease are often symptomatic and are more likely to have abdominal disease than the nodular sclerosing subtype.

54. Nodular sclerosing (NS). the only subgroup more common in female patients. Typically patients present in adolescence or early adulthood, The mediastinal and supraclavicularlymph node groups are involved.

55. Location Nodal disease Hodgkin's disease is usually almost entirely confined to the lymph nodes . Extranodal disease uncommon may be found in any organ system, either as a primary manifestation or as dissemination of systemic disease. Extranodal disease may occur via invasion of adjacent tissue or via haematogenous spread . Disseminated disease carries a poorer prognosis.

56. Patients with NS Hodgkin's disease typically have large lymph nodes at presentation. These slowly reduce in size on successful therapy. Residual soft tissue masses may persist . Interpretation of radiological findings at this time may be difficult. A surveillance strategy can therefore be used with early repeat scanning. If the original staging showed bulk disease then radiotherapy can be added to a chemotherapy protocol . Other imaging strategies would include gallium-67 scan or PET imaging to investigate for any active disease

57. The presence of fibrous stroma around the lymph nodes is important radiologically . CT scanning will initially demonstrate contiguity between the enlarged lymph nodes and adjacent structures, but early tumour invasion of contiguous structures is difficult to recognise radiologically .

58. Cotsworld -modified Ann Arbor Classification stage I:  one nodal group or lymphoid organ (e.g. spleen or thymus) stage IE:  one extranodal site stage II:  two or more nodal groups, same side of diaphragm stage IIE:   localised extranodal site with stage II criteria, both on the same side of the diaphragm stage III:  nodal groups on both sides of the diaphragm stage IIIS(1):  with splenic involvement stage IIIE(2):  with localised extranodal site stage IIISE:  both stage IV:  disseminated involvement of one or more extralymphatic organ (e.g. lung, bone) with or without any nodal involvement Additional sub-staging variables: A:  asymptomatic B:  presence of B symptoms (including fever, night sweats and weight loss of over 10% of body weight over 6 months) X:  bulky nodal disease: nodal mass >1/3 of intrathoracic diameter or 10 cm in dimension

59. Treatment and prognosis Prognosis depends on stage as well as several other factors such as age, serological markers (ESR), presence of B symptoms, and histological tumour subtype: nodular lymphocyte predominant: best prognosis lymphocyte depleted: worse prognosis Treatment is dependent on the stage of disease: stage IIa and below:  localised radiotherapy stage IIb and above: chemotherapy +/- radiotherapy to sites of large tumour bulk

60. Non hodgkin lymphoma heterogeneous group of malignant tumours than the Hodgkin's lymphomas. most frequently seen in the elderly. differ from Hodgkin's disease in that nodal disease is not contiguous, extranodal presentation and spread is common and the disease normally presents as stage 3 or 4 often with bone marrow involvement.

61. Sub types: Follicular Diffuse Follicular lymphomas are usually low grade while diffuse lymphomas are generally intermediate or high grade.

62. NHL Present as painless enlargement of lymph nodes , but the disease may also develop at a number of extranodal sites , leading to a wide variety of presenting features . Nodal enlargement at a number of palpable and radiologically obvious sites. These are often noncontiguous. The most common site is the neck, the lymphoid tissue of Waldeyer's ring is usually involved.

63. Patient with NHL is much more likely to present with enlarged lymph nodes in unusual sites, for example those of the elbow or knee, than a patient with Hodgkin's disease. The secondary effects of lymph node enlargement such as limb swelling or superior vena cava obstruction are seen. Backache is suggestive of retroperitoneal lymph node involvement . Constitutional symptoms, especially weight loss, fever and anorexia, are typical

64. Only about one-third of patients will have clinically localised disease at presentation. Most patients with NHL will have extensive disease and qualify for chemotherapy So, radiological staging are no longer required for treatment planning

65. The prognosis is worse in men, in patients with large abdominal nodal masses and in those with hepatic or marrow involvement. The proportion of complete responders is greatest in those with stage II disease, and falls to 60% in those with stage III disease, and to 35% in those patients with stage IV disease. The prognosis for incomplete responders is poor, and almost all these patients will be dead in 2 years . Recent attention has focused on early use of ultra-high-dose therapy with autologous bone marrow grafting for both Hodgkin's and NHLs in relapsed or poorly responding disease.

66. Extranodal presentations of the NHLs Extranodal sites of disease are commonly found on detailed staging of patients with a primary nodal presentation Previously treated nodal disease may relapse extranodally . The NHLs may also present at an extranodal site without clinically obvious nodal disease . These patients may be difficult to diagnose and to treat. Histology demonstrates that in advanced NHL extranodal disease is considerably more common than is recognised on imaging

67. CENTRAL NERVOUS SYSTEM LYMPHOMA Primary NHL represents about 1% of primary brain tumours The incidence is highest in immunocompromised patients (AIDS or renal transplants or on longterm Immunosuppression ) Treatment is primarily irradiation Prognosis is poor. Primary Hodgkin's disease of the brain is rare. Secondary central nervous system lymphoma is most frequently seen in high-grade tumours , especially in children and those with T-cell disease.

68. 50 % of these patients with central nervous system involvement will develop cord compression. 50% will show evidence of lymphomatous meningitis with nerve and root lesions, raised intracranial pressure and mental confusion Central nervous system involvement is also a feature of testicular, orbital head/ neck primary sites. At all times when CT or MRI scanning any patient with a known lymphoma, the paravertebral tissues should be closely examined.

69. HEAD AND NECK LYMPHOMA Primary nodal lymphomas arising in the head and neck do not require CT staging of the neck . Clinically palpable Abdominal CT staging is useful, as the disease often relapses outside the head and neck, typically in the gastrointestinal tract. Extranodal NHL of the head and neck is usually associated with disease dissemination in the body and a poor prognosis.

70. THORACIC LYMPHOMA Involvement of the lungs is a common feature of both NHL and Hodgkin's disease. In high-grade NHL, pulmonary involvement may be extensive and explosive, the radiological appearances often mimicking those seen in infection. Some of these arise in the bronchus-associated lymphoid tissue. In patients with more typical variants of NHL, thoracic involvement of the lungs and mediastinum is less common than for Hodgkin's disease and is normally associated with disease elsewhere.

71. BONE LYMPHOMA Bone marrow involvement is commonly found in the NHLs P rimary bone NHL are most common in younger patients, and involve the appendicular skeleton, especially in the metaphyseal region. Radiologically , the most common appearance is a permeative destructive lesion. Full radiological staging of the abdomen and chest should be undertaken, and a high percentage of patients will prove to have disseminated disease . MRI is significantly better than CT in demonstrating occult marrow infiltration

72. TESTICULAR LYMPHOMA Testicular lymphomas occur in middle-aged and elderly men. 25% will be bilateral. Aggressive, high grade, and tends to spread not only to the regional lymph nodes in the abdomen but also to lung, the central nervous system,and in the neck to Waldeyer's ring

73. CROSS-SECTIONAL IMAGING IN LYMPHOMA THORAX CT is the current 'gold standard' for evaluating the extent of thoracic involvement in patients with Hodgkin's disease and, when required , for those with NHL. The pattern of lymphomatous involvement is different for Hodgkin's disease and NHL .

74. Hodgkin Lymphoma The anterior mediastinum is the focus from which Hodgkin's disease of the chest appears to spread . It is of value in those who are being considered for radiation therapy. It is extremely uncommon to have disease at other sites within the thorax in the absence of anterior mediastinal involvement. Recognition of adenopathy at this site is the first step to successful CT scan interpretation. Mediastinal lymph nodes more than 1 cm in diameter are interpreted as being involved. Hilar nodal enlargement usually follows mediastinal involvement.

75. The typical CT appearance of a nodal mass in a patient with Hodgkin's disease is usually that of a homogeneous soft-tissue mass with sharply defined and often lobulated borders . Occasionally the centre of the nodal mass contains an area of decreased attenuation due to necrosis. If intravenous contrast medium has been given, the lymph node may enhance .

76. Normal mediastinal structures, in particular blood vessels, should be routinely identified. Care should be taken to recognise any aberrant vessels that may mimic adenopathy , particularly on non-contrast-enhanced scans. The superior pericardial recess may also be confused for adenopathy but normally has lower density and a concave anterior border

77. CT scanning of the lungs may show evidence of Hodgkin's disease . Characteristic finding : presence of one or more nodules within the parenchyma, frequently seen near the lung bases and/or the pulmonary hila , suggesting a haematogenous spread. Others:patchy pulmonary shadowing, pulmonary consolidation and lobar collapse

78. Demonstrates pleural and pleurally based lesions. Pleural effusions in patients with Hodgkin's disease are benign, and are thought to be a consequence of lymphatic obstruction secondary to mediastinal and hilar lymph node involvement and enlargement. CT may be helpful in assessing the patency and diameter of airways, especially in children. Over half the children presenting with Hodgkin's disease show significant airway obstruction on CT examination.

79. Pulmonary involvement is uncommon in the patient with newly diagnosed Hodgkin's disease(10%) Parenchymal lesions in newly presented patients who have no mediastinal or hilar adenopathy are best considered not to represent Hodgkin's disease. Pulmonary disease is a feature of recurrent Hodgkin's disease, where it may be confused with infection, the effects of treatment . These include pulmonary consolidation and fibrosis following radiotherapy, drug reactions, and opportunistic infections during or following systemic chemotherapy.

80. Serial MRI and/or gallium-67 studies beginning before treatment commences may help distinguish active from inactive disease following chemotherapy. This is of potential value in tailoring the chemotherapy regimen (and toxicity) to the individual

81. NON-HODGKIN LYMPHOMAS The contribution that thoracic CT scanning might make in the management of patients with NHL is less certain, for several reasons. NHL is more likely to be widespread and require systemic therapy , T he mediastinum and lung less commonly involved. The presence of a pleural effusion in NHL usually reflects the presence of pleural tumour .. CT scanning to the diagnostic work-up of patients presenting with a new NHL may occasionally show additional sites of disease but does not result in a change in management.

82. ABDOMEN CT is now the standard method of imaging the abdomen in patients with lymphoma . Intravenous contrast is helpful at staging to detect extranodal disease although it is less important in follow-up scanning. Abnormal lymph nodes , retroperitoneal,mesenteric and pelvic lymph nodes may be recognised by an increase in size. Retroperitoneal nodes> 1.5 cm in diameter and retrocrural region nodes> 0.6 cm in diameter are considered abnormal. Spleen and liver are to be evaluated for focal deposits and enlargement.

83. HEAD, NECK AND SPINE Enlarged lymph nodes in the neck are usually palpable . CT may show lymph node enlargement and/or central necrosis within the lymph node, the latter being a certain sign of a pathological condition In addition, CT imaging may show that a single palpable mass consists of a conglomerate mass of several enlarged lymph nodes Contrast CT and MRI may demonstrate ring enhancement of lymph nodes with metastasis

84. Size dependant criteria most nodes should be <10 mm in short-axis except: submental / submandibular and jugulodiagastric : <15 mm retropharyngeal: <8 mm if using size criteria alone then there is a 10-20% error rate The long-to-short axis ratio of >2 (i.e. long and flat) 95% are benign. When the ratio <2 (i.e. rounder) then a similar proportion were malignant. Size independent criteria loss of fatty hilum focal necrosis cystic necrotic nodes

85. MRI is the investigation of choice for CNS and spine imaging. MRI provides a more complete picture of the compressive lesion and the assessment of bone marrow involvement. The MRI do not allow the cause of the enlargement, or whether the underlying pathology is benign or malignant, unless central necrosis is recognised by central high signal on T2 (or low signal onT1 ) or contrast-enhancement characteristics.

86. I MAGING THE COMPLICATIONS OF DISEASE AND THERAPY Lymphoma can invade extranodally to cause a variety of complications Spinal invasion from nodal or extranodal disease should be checked as treatment is not as effective once symptoms present. Obstructive features shoud be evaluated. Airway obstruction B iliary dilatation and jaundice due to portal nodes H ydronephrosis secondary to retroperitoneal nodes or bladder lymphoma

87. Treatment itself can cause a variety of complications :atypical infections, recurrent disease, haemorrhage and graft versus host disease Specific chemotherapy agents have different complications including doxorubicin affecting cardiac function , bleomycin and cyclophosphamide causing lung fibrosis, and vincristine causing neuropathy and ileus . Radiation changes can cause fibrosis in both the chest and Abdomen . The effect of bleomycin can occur months after its caesation .

88. Strategies for imaging the lymphatic system in malignant disease 1) Diagnosis and T N M staging 2)Treatment planning 3)Radiotherapy planning 4)Response to treatment

89. WHO criteria state a reduction in tumour size on CT of greater than 50% of the product of its diameters in the axial plane is a partial response (PR ), Objective disappearance of tumour should be regarded as a complete response (CR ). In both cases the response should be confirmed at imaging at least 4 weeks later . Progressive disease is an increase of more than 25% or the detection of new lesions.

90. Residual masses It is not possible to deduce residual malignant potential from the appearances. PET may provide the best imaging strategy with future possible strategies using radionuclides targeted to the specific cell types . If MRI scans show residual tumour masses as low signal intensity on T 2-weighted images, especially when the pretreatment images showed high signal, these are likely to be dormant .

91. Others disorders Lymphangioma Congenital, benign lesion that results from focal, excessive proliferation of lymphatics Represents an isolated cluster of abnormal lymphatics that swells as lymph accumulates within it . The most common location is the neck referred to as “cystic hygroma ” In the thorax, it is usually mediastinal , Rarely presents as a solitary intrapulmonary lesion Other rare locations are the pulmonary hila and the pericardium Common in women than men, with a mean age at diagnosis of 36.5 years 

92. imaging findings: homogeneous, thin-walled, well-circumscribed, and low in attenuation lymphangioma may contain higher-attenuation fluid reflecting high protein content, hemorrhage, or infection. Calcification or contrast enhancement is atypical . Classically, as in the neck, these lesions insinuate and spread throughout the mediastinum . Septations more common in neck On MRI, the cyst shows high T2 and low T1 signal. Internal septations are more apparent than on CT, especially on gadolinium-enhanced or T2-weighted images

93. Lymphangiohemangioma rare lesion clinically behaves like lymphangioma and is often misdiagnosed as a lymphatic malformation. It is a low-flow lesion combining vascular and lymphatic elements. Depending on the extent of the vascular component, there can homogeneous or heterogeneous contrast enhancement. Tiny cysts correspond to dilated lymphatic channels. Phleboliths , punctate calcifications, and puddling contrast enhancement, which are characteristic of pure hemangioma . The anterior mediastinum is probably the most common location.

94. Pulmonary lymphangiomatosis rare, systemic, multiorgan disease resulting in marked proliferation and dilation of lymphatics . It is most common in children and affects both sexes equally It can involve any part of the body containing lymphatics but tends to involve the chest and mediastinum It differs from pulmonary lymphangiectasis in that the lymphatics are not only dilated, but also increased in number and extensively interconnected

95. diffuse, bilateral, symmetric, and interlobular septal and peribronchovascular thickening Patchy ground-glass attenuation Lymphatic proliferation diffusely infiltrates the mediastinum and thickens the visceral and parietal pleura. Pleural effusion is common

96. Pulmonary lymphangiectasis congenital abnormality that causes dilation of septal , subpleural , and peribronchial pulmonary lymphatics and carries high mortality CT findings resemble those of pulmonary lymphangiomatosis : bilateral groundglass opacity, smooth interlobular septal thickening, marked pleural thickening, and mediastinal soft-tissue infiltration .

97. In lymphangioleiomyomatosis (LAM), the fundamental disorder is abnormal smooth-muscle proliferation in the lung, but the involvement of lymphatics justifies including it with other lymphatic disorders. It is rare (2.6 cases per million) and primarily affects women of child-bearing age. LAM leads to respiratory failure, often requiring lung transplantation. It can also cause recurrent pneumothorax and chylous pleural effusion [ 2 ,  22 ]. There is a strong association between LAM and the tuberous sclerosis complex, with up to one third of women with tuberous sclerosis complex presenting with LAM [ 22 ]. The pathophysiology of LAM is abnormal proliferation of smooth muscle cells (LAM cells), which can obstruct bronchi, veins, and lymphatics . Obstruction of bronchioles leads to the classic radiographic finding: multiple, round, thin-walled, regular lung cysts that can involve any part of the lung (unlike Langerhans cell histiocytosis , in which cysts spare the costophrenic angles) [ 2 ,  23 ]. The cysts tend to be regular and round, but can lose roundness when confluent [ 24 ]. Lung involvement is typically symmetric and uniform, without air trapping [ 24 ] (Figs.  8A ,  8B ,  8C ,  8D ,  8E  and  9A ,  9B ,  9C ,  9D ). Pneumothorax is the presentation in 40% of cases, and recurrent pneumothorax may necessitate pleurodesis [ 24 ].

98. When smooth-muscle proliferation obstructs lymphatics , it can cause recurrent chylous pleural effusion. The effusion can be unilateral or bilateral and can be large enough to cause dyspnea . Chylous and serous effusions cannot be distinguished by CT. Treatment is difficult and repeated thoracentesis can cause protein loss [ 24 ]. Smooth-muscle proliferation can also lead to obstruction of mediastinal and retroperitoneal lymphatic channels and formation of lymphangioleiomyomas . These cystic lymphatic channels have thin or thick walls and contain low-attenuation fluid. They are less common in the mediastinum than in the abdomen, where they are found in up to 20% of cases (Fig.  9A ,  9B ,  9C ,  9D ). Finally, dilation of the thoracic duct is common in LAM [ 24 ].

99. Diseases with lymphatic distribution Lymphangitic Carcinomatosis Pulmonary lymphangitic carcinomatosis refers to the spread of tumor along lymphatics located in the interlobular septa, subpleural lung, and peribronchovascular interstitium . Pathologically, it manifests as tumor emboli in lymphatic vessels, most commonly from bronchogenic , breast, or gastric carcinoma . High-resolution CT shows nodular thickening of the peribronchovascular , interlobular, and subpleural interstitium . Pleural effusion and mediastinal lymphadenopathy are common.

100. Traumatic lymphatic injury injury to the thoracic duct can lead to chylothorax Injury is more often caused by penetrating than blunt trauma and usually only from hyperextension spine injuries or posterior rib fracture Thoracic duct injury can be an iatrogenic complication of percutaneous and open surgical procedures, particularly esophagectomy . Thoracic duct injury with chylothorax causes morbidity and mortality. Low-volume leaks are usually treated conservatively with drainage of the effusion and dietary restriction to minimize the production of chyle . If persistent drainage after 2 weeks , ligation of the thoracic duct.

101. CT cannot directly show the injury to the thoracic duct and serves only to document the persistent pleural effusion . In addition, the course of the thoracic duct is variable, limiting the usefulness of CT. Only 65% of people have usual ductal anatomy, and up to 33% have two thoracic ducts Also, CT does not distinguish chylous from serous pleural effusion Of more use is lymphangiography, which may show the site of the leak

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103. References: Textbook of Radiology and Imaging ,David Sutton Imaging of Thoracic Lymphatic Diseases, American Journal of Roentgenology .  Advances in Imaging of Lymph Flow Disorders, RSNA article Radiopedia .