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1. BONE TUMORS PART1 -BASICS AND BENIGN TUMORS

2. Bone tumors may be defined as a new growth arising in a bone or derived from cells which are components of skeletal tissue. For diagnosis of bone tumors and tumor -like lesion, there is need for close cooperation of radiologist, orthopedician , and pathologists; however, the role of radiologist is most important . Primary Aim Of Imaging Should Be To Make Specific Diagnosis (If Possible) Or Narrowing Of The Differential Diagnosis w majority of benign true tumors of bone are detected in children and young adults. Benign bone tumors can be classified according to their matrix production and/ or predominant cell type into cartilage forming, bone forming, fibrous, vascular, and other connective tissue lesions “ Tumor -like lesions of bone” denotes various conditions of non-neoplastic nature originating from or affecting the bone and presenting as solitary or multiple bone lesions

3. Plain X rays SEVEN 1. Where is the lesion – what bone and what part of the bone 2. Age & size of the lesion? 3. What is the lesion doing to bone? 4. What is the bone doing in response? 5. Is the lesion making matrix? 6. Is the cortex eroded? 7. Is a soft tissue mass evident?

4. LOCATION In the transverse plane a) Central – Enchondroma b) Eccentric -GCT, osteosarcoma , chondromyxoid fibroma c) Cortical - Non-ossifying fibroma , osteoid osteoma d) Parosteal - Parosteal osteosarcoma , osteochondroma 2 . In the longitudinal plane: Diaphyseal : Ewings , Osteoid Osteoma , Mets, Adamantinoma , Fibrous Dysplasia Epiphyseal : Chondroblastoma,GCT , Ganglion of Bone. Metaphyseal : Everything!!!!!! ECG

5. Chondroblastoma - Epiphyses Giant Cell tumor - Epiphyses Simple bone cyst - Proximal humerus Adamantinoma - Tibia Chordoma - Sacrum Osteoblastoma - Posterior element of spine Chondrosarcoma - Pelvis Characteristic Location Some tumors almost exclusively occur at specific sites Epiphysis Chondroblastoma Spine, posterior Osteoblastoma

6. Tibia Sacrum, clivus Adamantinoma Chordoma

7. Giant Cell tumor Simple bone cyst Epiphyses Proximal humerus

8. 20>….. Osteogenic Sarcoma, Ewings . simple bone cysts and chondroblastomas 40……GCT, Chondrosarcoma , MFH, Lymphoma, Mets. 60……Mets, Myeloma, Chondrosarcoma , MFH Late Osteogenic , Fibrosarcoma . Age of the patient

9. Size In general The larger the lesion the more likely it is to be aggressive or malignant The bigger the uglier (some exceptions i.e. fibrous dysplasia)

10. Bone reacts in two ways -- either by removing some of itself or by creating more of itself . If the disorder is rapidly progressive, there may only be time for retreat (defense ). If the process is slow growing, then the bone may have time to mount an offense and try to form a sclerotic area around the offender. What is the bone doing to the tumor ?

11. A periosteal reaction will occur whenever the periosteum is irritated. This may occur due to a malignant tumor, benign tumor, infection or trauma. T wo types Benign or Aggressive . Periostitis Benign None Solid Aggressive or malignant Lamellated or onion peel Sunburst Codman’s triangle

12. Solid L amellated Spiculated Benign Aggressive V . Aggressive Codman's

13. Solid Periosteal Response Related to a slow form of irritation osteoid osteoma Slow-growing tumors provoke focal cortical thickening A continuous layer of new bone that attaches to outer cortical surface

14. Single layer of reactive periosteum . … thick unilamellated periosteal reaction . Smooth and continuous Unilamellated periosteal reaction Hypertrophic osteoarthropathy

15. Aggressive Periostitis appearance of aggressive periostitis in Ewing’s sarcoma Layered, onion-skin, lamellated Alternating layers of opaque and lucent densities Can be seen with slow growing and aggressive tumors and infections growth spurt.

16. Bone is formed in a disorganized fashion Process may destroy spicules of bone as they are being formed This is a very aggressive process “sunburst ”

17. Too fast growth for periosteum to respond only the edges of raised periosteum will ossify forming a small angle with the surface of bone. Codman's triangle seen in malignant bone tumors and in rapidly growing lesions .. aneurysmal bone cyst, subperiosteal hematoma .

18. Periosteal Reactions Solid onion-peel Sunburst Codman’s triangle Less malignant More malignant

19. NARROW ZONE WIDE ZONE ZONE OF TRANSITION

20. Three Patterns of Bone Destruction Geographic Pattern Moth-Eaten Pattern Permeative Pattern Result from the degree of aggressiveness of the lesion

21. geographic lesion. (a) Diagram shows well-defined lucency with sclerotic rim. (Adapted and reprinted, with permission, from reference 1.) (b) Lateral radiograph shows intraosseous lipoma of the calcaneus, with a sclerotic rim (arrows). Type 1a geographic lesion. (a) Diagram shows well-defined lucency with sclerotic rim. (Adapted and reprinted, with permission, from reference 1.) (b) Lateral radiograph shows intraosseous lipoma of the calcaneus, with a sclerotic rim (arrows). Type 1 a Geographic L esion . Intra osseous lipoma with a sclerotic rim . Well-defined lucency with sclerotic rim .

22. Well-defined geographic lytic focus without sclerotic rim , Endosteal scalloping seen. Type 1 b Geographic L esion well-defined lucent lesion without sclerotic rim. myeloma

23. Large ill-defined lytic lesion , Codman’s triangle Periosteal interruption, Tumor-induced new bone . . Type 1 c Geographic L esion ill-defined lytic lesion osteosarcoma

24. IA: GEOGRAPHIC DESTRUCTION WELL – DEFINED WITH SCLEROSIS IN MARGIN IB: GEOGRAPHIC DESTRUCTION WELL – DEFINED BUT NO SCLEROSIS IN MARGIN IC : GEOGRAPHIC DESTRUCTION WITH ILL DEFINED MARGIN increasing aggressiveness Margins: 1A, 1B, 1C

25. Type 2 Moth-eaten Appearance Areas of destruction with ragged borders Implies more rapid growth Probably a malignancy osteosarcoma

26. Type 3 . Permeative Pattern Ewing sarcoma. ill-defined lesion with multiple “worm-holes” Spreads through marrow space Wide transition zone Implies aggressive malignancy Round-cell lesions Leukemia

27. Patterns of Bone Destruction Geographic Moth-eaten Permeative Less malignant More Malignant

28. Is the Cortex Eroded? Cortical erosion is hallmark of active, aggressive, or malignant tumors. High-grade malignant tumors may erode through cortex with ineffective periosteal response to erosion In general, low grade tumors will produce endosteal erosion with orderly response; high grade tumors will erode through the endosteal surface without adequate response, increasing surface risk of fracture

29. Ewings sarcoma Complete destruction may be seen in high-grade malignant lesions, but also in locally aggressive benign lesions like EG and osteomyelitis . Osteosarcoma

30. Ewings sarcoma Complete destruction may be seen in high-grade malignant lesions, but also in locally aggressive benign lesions like EG and osteomyelitis . Osteosarcoma

31. Cortical erosion Thinning of the cortex by an intraosseous process "Cortical Erosion" destruction of cortex by a lytic or sclerotic process. " Endosteal Scalloping"

32. Giant cell tumor. Malignant

33. Cortical destruction In tumors like Ewing's sarcoma, lymphoma and small cell osteosarcoma , cortex may appear normal radiographically , while there is permeative growth throughout Haversian channels. These tumors may be accompanied by a large soft tissue mass while there is almost no visible bone destruction.

34. Cortical Destruction The presence of cortical destruction is not a reliable indicator of whether the lesion is a malignant process or a benign process . Other radiographic findings must also be examined.

35. Is the lesion making matrix? Matrix is the dominant internal extracellular substance of a lesion. Most tumor have soft tissue matrix-Radiolucent ( lytic ) on X-ray Chondroid matrix -Calcified rings, arcs, dots Osteoid matrix- Bone forming

36. "Clear Matrix" refers to lesions which are clear or mostly clear. A radiolucent lesion with few undestroyed trabeculae is considered to have a clear matrix. Clear Matrix

37. Patterns of mineralization of cartilaginous tumor matrix Stippled Flocculent Ring and arc

38. Chondral mineralization. (a) Diagram shows patterns and of mineralization of cartilaginous tumor matrix: stippled (left), flocculent (middle), and ring and arc (right). (Adapted and reprinted, with permission, from reference 3.) (b) Lateral radiograph of proximal portion of tibia shows enchondroma with punctate and arclike mineralization (arrows). Enchondroma Punctate and arc like mineralization Chondrosarcoma

39. Chondral -type matrix mineralization and endosteal scalloping . chondrosarcoma

40. Solid Patterns of mineralization of osseous matrix Ivory-like opacity Cloudlike

41. Benign vs. Malignant

42. pointers to the benign nature of a bone tumor Area of geographic bone destruction which is well- circumscribed and is characterized by a sharp transition between the destroyed area and the normal bone (i.e., narrow zone of transition—less than 1 cm ). Sclerotic margin indicates slow growth and is generally seen in benign lesions located at the metaphysis . Certain tumors stimulate surrounding sclerosis which may obscure the central lytic area such as osteoid osteoma . Periosteal reaction: In general, periosteal reaction is not a feature of benign bone tumors unless a fracture has occurred except in a very few lesions such as osteoblastoma , osteoid osteoma , and chondromyxoid fibroma . Periosteal reaction is radiographically described as solid or interrupted. Solid periosteal reaction is defined as a single layer of new bone >1 mm in thickness which is usually of uniform density. When seen, solid periosteal reaction indicates benign pathology. It is seen in osteoid osteoma and osteoblastoma . • Tumor matrix : Presence of calcification in the form of rings, flocculant patches, or stippled flecks point to the cartilaginous origin of the tumor . A ground-glass haze indicates fibrous lesions. Osteoid matrix is seen in bone-forming tumors

43. consideration of patient's data (age, gender) and clinical information of concerned patient are very useful for diagnosis as many lesions of bone show predilection for particular age group and gender . ROLE OF X RAY location of the tumor in the body; segment involved—whether epiphysis, metaphysis , or diaphysis ; growth characters of the lesion such as margin—well-defined/ill-defined; presence or absence of periosteal reaction and the appearance of tumor matrix—whether calcified or not

44. Imaging Modalities Plain Radiograph- Fast and cheap Identifies aggressive vs nonaggressive lesions Suggests the presence of malignancy CT scan- Computed tomography (CT) can be used in the region of complex anatomy and superimposition of bony elements (pelvis, spine, and scapula). determination of the epicenter of a bone lesion, whether it is in cortex, medulla, or periosteal in location. to detect cortical alteration (breech, scalloping, expansion) and detection of periosteal reaction. in detection of subtle matrix calcifications it is very useful for diagnosis of a bone- or cartilage-forming benign bone tumor

45. Magnetic Resonance Imaging for demonstrating extent of tumors especially intramedullary component . significant potential for tumor characterization. On T1-weighted (T1W) images, most bone tumors show decrease in signal intensity because of marked contrast with hyperintense fat of the marrow. On T2-weighted (T2W) images most of the tumors are of high-intensity making it difficult to separate tumor from fat but easy to differentiate tumor from surrounding muscles. Presence of atypical signal patterns help in predicting a dominant tissue component, e.g., high-signal intensity on T1W images may be due to fat, as seen in lipoma, hemangioma, medullary bone infarct or hemorrhage as seen in aneurysmal bone cyst. demarcating the soft tissue component of bone tumors and its relationship to adjacent joint and neurovascular structures. Generally, only few bone tumors have a classical radiological picture. Similarly, biopsy of the lesion is not always the ultimate answer. On the other hand, some tumors are difficult to diagnose histologically but have a typical radiographic appearance, e.g., osteoid osteoma . Others with unusual radiographic features exhibit a characteristic histological appearance, e.g., aneurysmal bone cysts

46. BONE-FORMING TUMORS Enostosis - commonly known as “bony islands” are usually asymptomatic

47. Enostosis Commonly known as bone islands Bones commonly involved:-spine ,ribs and pelvis. X-ray And CT:- oval densely sclerotic lesion Scintigraphy and MRI are helpful in the differentiation, as bony islands usually do not exhibit an increase tracer uptake on bone scans. On MRI, enostosis shows hypointense signal on both T1W and T2W sequences Intramedullary .

48. Osteoid Osteoma Benign, slow growing . 5 and 25 years of age. pain that is especially severe at night and relieved by aspirin or other NSAIDS Arises from the cortex. Broad base, smooth well defined margin Common sites:-outer table of skull,PNS ( frontal and ethmoidal),mandible. proximal femur and tibia. less frequently in the upper extremities than in the lower extremities, less common in the spine, where they affect the posterior arches of the vertebrae c/f – asymptomatic IMAGING-radio dense lesions ,protrudes from surface, similar density of cortex. MRI-hypointense on T1W & T2W. When craniofacial osteomas are detected, the possibility of Gardners syndrome should be considered, particularly if lesions are present in the mandible. Intra-articular osteoid osteomas produce joint effusions and synovial proliferation

49. Osteoid osteoma can be cortical (the most common type), cancellous or medullary, and subperiosteal.The latter two types produce less sclerotic bone than those in the cortex do, making radiologic diagnosis difficult.

50. MRI Display the nidus better. Nidus :-hypo to intermediate signal T1W Low to high signal on T2W. Shows enhancement on contrast. Computed tomography is very useful in showing the nidus , which can vary in its degree of ossification. CT appears to display the nidus better than MRI. Intense bone marrow edema adjacent to nidus is very useful to detect and localized the lesion on MRI

51. Osteoblastoma Osteoblastomas are rare bone-forming tumors 2nd & 3rd decade of life. Males> females. Similar to osteoid osteoma ( oo ) ,SIZE is helpful to differentiate , oo <2cms and lesion >2cms osteoblastoma . X-ray:- In spine osteolytic lesion with destructive cortex and may extend up to spinal canal. Long bones :- oval or round lucent tumors in the medulla. Periosteal reaction is common. MRI-useful for extension to spinal canal.

52. CARTILAGE-FORMING TUMORS Osteochondroma common lesions of the growing skeleton most common benign neoplasm arise from bony metaphysis with cartilage cap covering Multiple osteochondroma occur as a manifestation of diaphyseal aclasia long axis of the osteochondroma pedicle or stalk is almost always directed away from the adjacent joint. The direct communication between the osteochondroma and the cortex and marrow cavity of the bone from which it arises is a distinctive feature, that is particularly well demonstrated on CT and MRI

53. .T2W proton density (PD) MR images are useful to demonstrate a cartilaginous cap After epiphyseal closure, growth of the osteochondroma ceases. Because most osteochondromas are asymptomatic, they are usually discovered incidentally. However, mechanical irritation of adjacent soft tissues or nerves, vascular injuries, fracture of the stalk, or malignant transformation can produce symptoms. Malignant transformation into low-grade chondrosarcoma occurs in 1% of osteochondromas ; however, the risk is 10–30% in cases of multiple osteochondromatosis.17 Malignant transformation should be considered when the osteochondroma grows after epiphyseal closure. Malignancy occurs in the cartilaginous cap, which becomes thickened. After skeletal maturity, the cartilage cap should not be thicker than 2 cm. Pain and cartilage cap growth are the signs of malignant transformation

54. Enchondroma Affects commonly hands and feet. X-ray and CT :- lobulated growth pattern. Characteristic cartilaginous ring and arc pattern of calcifications is seen on radiographs and CT images. On MRI, the tumor is isointense to muscle on T1W and exhibits a heterogeneous, predominantly high T2W signal. C ontr ast -enhanced MRI may demonstrate a pattern of thin arcs and rings . symmetrical expansion of medullary cavity and endosteal scalloping. Radiolucent tumor matrix. Calcification:- cartilaginous ring and arc like pattern of calcification.

55. Enchondroma

56. Periosteal chondroma Enchondroma rib

57. Ollier's disease is a nonheritable disorder of cartilage proliferation in which enchondromas involve multiple bones, especially those of the hands and may result in skeletal deformity Enchondromatosis accompanied by multiple hemangiomas is known as Maffucci syndrome. . Lesions associated with both Ollier disease and Maffucci syndrome carry a significant risk of malignant degeneration

58. the phalanges, with varying amounts of calcification within them.

59. T1W:- isointense to muscle. T2W:- heterogeneous predominantly high signal. On contrast:- thin arcs and rings seen.

60. Chondroblastoma 10 -25 yrs. located in epiphysis and apophysis of bone, most often the proximal humerus , distal femur and proximal tibia. On plain X-ray eccentric, lucent, well-defined lesion with sclerotic borders. Periosteal reaction may be seen. calcified matrix (better seen on CT).

61. Chondroblastoma T1W:- isointense to muscle Hypointense rim. T2W:- low to intermediate. This tumor also shows extensive surrounding inflammation which may be confused with more aggressive lesion. differential diagnosis of epiphyseal lesions giant cell tumor, osteomyelitis, subchondral cyst and langerhans cell histiocytosis .

62. Age< 35 yrs. Affects males. The common locations of tumor are ilium, tibia and bones of foot. located characteristically in metadiaphyseal location unlike chondroblastoma and do not cross an open growth plate. On plain radiograph, it appears as a well marginated central or eccentric lucent? CT shows expansile lytic lesion in epiphysis (characteristic location) with matrix calcification lesion, with sclerotic margins and cortical thinning . Half of the lesions may show parallel orientation to the long axis of the involved bone. Matrix calcification and periosteal new bone formation usually do not occur. Chondromyxoid fibroma

63. FIBROUS TUMORS/LESIONS Fibrous Cortical Defects and Nonossifying Fibroma are basically similar benign fibrous lesions located slightly differently, nonossifying fibroma being located eccentrically in the medullary cavity, fibrous cortical defect seen superficially affecting the cortex. location -in the bones around the knee joints . usually asymptomatic and not require specific treatment

64. plain radiography, the lesion appears as well-marginated eccentric lytic lesion with scalloped margin. Its inner border is often sclerotic and may appear multilocular due to corrugations. Differential diagnosis includes unicameral bone cyst, aneurysmal bone cyst, fibrous dysplasia, and chondromyxoid fibroma . MRI – signal intensity of nonossifying fibroma is equal to or less than muscle on T1W MR images and hypointense on T2W images.22 Postcontrast images usually show heterogeneous enhancement.

65. Fibrous Dysplasia bone is replaced by abnormal fibrous tissue. Fibrous dysplasia can be monostotic , polyostotic , monomelic , or polymelic . more common in young females, seen in the first decade of life. associated with endocrine disorders, especially precocious puberty in girls (McCune–Albright syndrome ). Fibrous dysplasia causes expansion of the medullary cavity of tubular bones, endosteal scalloping, and trabeculation . The margin is sclerotic . The lesion may appear as ground glass or radiolucent, and this depends upon amount of fibrous tissue within the lesion . Bowing of the affected long bone may occur, when the affected bone is femur, the resulting deformity is called a “shepherd's crook” . Thinning and destruction of the bony cortex may be seen on CT or MR images. Soft tissue extension of the lesion is unusual. On T1W MR images, the signal intensity of fibrous dysplasia is similar to that of skeletal muscle. Although the signal of pure fibrous tissue is hypointense on T2W images, the signal of fibrous dysplasia is variable.

66. FIG. 17: Polyostotic fibrous dysplasia. Radiograph of pelvis shows multiple lytic lesions involving pelvic bones and bilateral femora with characteristic shepherd's crook deformity.

67. Osteofibrous Dysplasia Rare Lesion that is usually confined to the tibia but can also involve the fibula . first decade of life Plain X-ray, the lesion appears as an eccentric, lucent, solitary, or multiloculated , lesion involving the anterior aspect of tibia . CT is very helpful in determining its intracortical location, an important feature in distinguishing osteofibrous dysplasia from fibrous dysplasia

68. Desmoplastic Fibroma rare accounting for only 0.1% of benign bone tumors . second and third decade of life . infiltration of abnormal fibrous tissue in the bone and at times it is confused with low-grade fibrosarcoma of bone . located in the metadiaphysis of long bones but may invade the epiphysis. Femur, tibia, and humerus are most commonly affected lesion has aggressive appearance and present as lytic expansile lesion with internal trabeculation and sclerotic margin. CT may demonstrate cortical breech and adjacent soft tissue if any. MRI typically shows intermediate to low signal on fluid sensitive sequences

69. VASCULAR AND CONNECTIVE TISSUE TUMORS Hemangioma- slowly growing lesions of bone composed of newly formed vascular spaces. About 50% of hemangiomas of bone occur in vertebrae and are most commonly located in lower thoracic and upper lumbar regions. About 20% of hemangiomas occur in skull . Small bones of the hand and feet may also be affected. Hemangioma of the vertebra has a typical radiographic picture in the form of coarse vertical striations on the plain radiographs and polka dot appearance on CT. High intensity on both T1W and T2W images . Hemangioma generally affects the calvarium and is seen as an expansile lytic lesion which has a sunburst appearance with striations radiating from the center . Short and long bones, the lesion lacks characteristic features and may be difficult to differentiate from other expansile central lesions such as aneurysmal bone cyst, chondromyxoid fibroma , or enchondroma

70. Lipoma Intraosseous lipoma is a rare benign neoplasm occurs between 5 and 70 years of age proximal femur, tibia, and calcaneum are the most common sites. well-defined osteolytic lesion with a thin sclerotic rim. Bone expansion and trabeculations may be seen within the lesion. Cortical erosion and periosteal reaction are characteristically absent. In the calcaneum, the lesion usually occurs along the plantar margin where a “triangle” is formed by major trabecular groups and there may be a calcified nidus . CT scan shows typical “fat” density (–60 to –120 HU) and lack of contrast enhancement . On MRI, lipoma typically shows high signal intensity on T1W image and iso to hyperintense signal on T2W image.

71. Giant Cell Tumor About 5% of all bone tumors and slightly less than 20% of all benign tumors . originates from undifferentiated cells of the supporting tissues of bone marrow. As opposed to other benign tumors , GCT has a female predilection and mostly occurs after the closure of epiphysis, with a peak in the third decade. arise eccentrically in the metaphysis with tendency to approach the adjacent subarticular cortex as they enlarge. 40–50% of lesions occur around the knee. Involvement of distal radius is seen in 10–12% , sacrum, short tubular bones, and vertebral bodies

72. Well-defined eccentric lytic lesion which expands the bone and is usually not surrounded by a sclerotic rim . Cortical penetration with or without an associated soft tissue mass is seen in 33–50% of cases. The solid portion of a GCT is usually low to intermediate signal intensity at T1W and T2W images. This has been attributed to its high collagen content, high cellularity , or presence of hemosiderin . GCT is the most common lesion associated with secondary aneurysmal bone cyst. Following contrast administration, there is diffuse enhancement of the solid component and peripheral or septal enhancement of cystic areas (Figs. 23A and B). GCTs are aggressive benign neoplasms with a high rate of recurrence.

73. TUMOR-LIKE LESIONS Simple Bone Cyst- a fluid-filled lesion with fibrous lining . occurs in metaphysis of long bones and adjacent to physis in children and young adults . locations are proximal humerus and femur.but Calcaneum and ileum are less common sites. Plain radiograph, the lesion appears as moderately expansile , well marginated with or without sclerosis . The cortex may be thinned out and may lead to pathological fracture . “Fallen fragment” sign has been described as pathognomonic features of bone cyst when fragment of bone settles at the base of lesion due to simple nature of fluid. “ Rising bubbles” sign is also based on similar principles . CT and MRI can confirm the cystic nature of the lesion. The fluid contents are usually of low intensity on T1W images and hypertense on T2W images.N /M/O , hemorrhage into the cyst can alter the signal characteristics of the lesion.

74. subarticular epiphyseal lesion of radius which is hyperintense on T2W image with central cystic area; (B) Postcontrast image shows homogeneous enhancement of solid component and no enhancement of cystic area. The cortical line on the lateral side is intact but shows disruption with extension of the tumor into the soft tissues on the medial aspect (arrow).

75. Aneurysmal Bone Cyst solitary, expansile radiolucent lesion and generally located in metaphysis of long bones . Other sites are dorsolumbar spine, small bones of hand, feet, and pelvis. Pathologically, the lesion contains multiples cystic spaces containing various stages of blood . Radiologically the lesion appears as expansile , lytic sharply circumscribed with thin cortex. The characteristic features are its ballooned out appearance and trabeculated appearance

76. CT may demonstrate fluid-fluid level and thin rim of bone overlying the lesion . MRI shows the various stages of blood products which appear as layers of different signal intensity on both T1W and T2W images (Figs. 26A and B). The differential diagnosis includes GCT, osteoblastoma , chondroblastoma , osteosarcoma , and simple bone cyst

77. Pseudotumor of Hemophilia bleeding disorder that occurs in males Repetitive hemorrhage within the bone may result expansile geographic lesion which can simulate neoplasm common locations are femur, pelvis, tibia, and hand . CT scan better demonstrates bony erosion/destruction with adjacent hematoma MRI shows variable heterogeneous signals, in form of various stages of blood products .

78. Eosinophilic Granuloma most benign form of histiocytosis X, which is a disease of unknown etiology characterized by proliferation of histiocytes . constitutes 60–80% of Langerhans cell histiocytosis . may be solitary (85%) or multiple (20%) with peak incidence between 5 and 10 years sites - skull, mandible, spine, and long bones

79. on radiographs is seen as a punched out lytic lesion having a bevelled appearance due to unequal involvement of outer and inner table, with a variably sclerotic margin

80. On plain radiographs, the lesions are seen as slightly trabeculated, solitary, or multiple expansile lytic lesions with well-defined margins Differentiation from a simple bone cyst is difficult when the lesion is solitary. Associated skeletal osteoporosis and biochemical changes, sclerotic appearance of brown tumor after removal of parathyroid adenoma, and the marked activity with scintigraphy are helpful in the diagnosis

81. Brown Tumor of Hyperparathyroidism Shows multiple well-defined expansile multiloculated lytic lesions in lower End of tibia and fibula.

82. THANK YOU

83. Introduction X-ray examination of the skeletal system is very common. Primary malignant bone tumors are fortunately very rare, however, it is important for the radiologist to recognize bone tumors and provide a differential diagnosis. Imaging Modalities Plain Radiograph- Fast and cheap Identifies aggressive vs nonaggressive lesions Suggests the presence of malignancy CT scan- Provides diagnostic information of bones and soft tissue in another plane.

84. Malignant Tumors diagnosed correctly 80% of the time using the patient’s age. STRATEGY FOR EVALUATING BONE LESIONS ON PLAIN FILM Differential by examining particular characteristics of the lesion on plain film include Location, Margins, Trabecular Pattern, Periosteal Reaction, and Soft tissue component