Extramedullary hematopoiesis

Incidental finding in patient with COVID-19 and well known case of thalassemia.

1. بسم الله الرحمن الرحيم

2. A 35 year old female presented with cough and fever for 3 days duration with suspicion of COVID-19 .The patient was sent for COVID-19 CT scan unite.

3. Finding: 1. Multiple different size patches of peripherally located consolidation more prominent seen in the lower lobes otherwise normal pulmonary attenuation, no mass no consolidation…..feature consistent with a mild form of COVID-19.

4. 2. There are paraspinal soft tissue density mass-like lesions seen scattered along the thoracic column .Some of those lesions show fine calcification.

5. 3. There is a clear visualization of the intraventricular septum indicating decrease density of the intraventricular blood.

6. 4. Diffuse increase in hepatic attenuation indicating iron overload.

7. On CT the normal density of the liver is between 45 and 65 HU on non-contrast scans obtained at 120  kVp . , and usually 8-10 HU greater than the spleen. On precontrast scans, CT density of normal splenic tissue amounts to 40 to 60 HU(in radiopaedia web site the HU range between 35-55) which is approximately 10 HU less than liver parenchyma. Increased values are observed in patients with thalassemia, sickle cell anemia, and hemochromatosis. However, changes in the density ratio most often are indicative of hepatic, not splenic, disease.

8. In patients with hemochromatosis, the liver demonstrates homogeneously increased density with an attenuation of greater than 72 HU . The increased attenuation highlights the lower attenuation hepatic and portal veins on unenhanced CT. A similar, diffuse pattern of increased attenuation can be seen in patients treated with amiodarone and in patients with glycogen storage disease that can be indistinguishable from iron overload with CT. 

9. PICTURE FROm the internet : Unenhanced transverse ct scan of normal liver shows attenuation value of liver parenchyma is 57 hu, slightly higher than that of spleen parenchyma of 48 hu

10. 4. Diffusely exaggerated bony trabecular pattern more prominently seen in the spine and sternum.

11. diagnosis Intrathoracic extramedullary hematopoiesis with hepatic iron overload (hemosiderosis/hemochromatosis)

12. EMH is a physiologic response to compensate for bone marrow dysfunction. It can occur in patients with either neoplastic process or chronic hemolytic anemia especially thalassemia, hereditary spherocytosis and sickle cell anemia.

13. The pathogenesis of this outside-bone marrow hematopoiesis is unclear. It may originate from extension of hyperplastic marrow through the thin cortex of ribs and vertebral bodies; the capsule of the mass is formed by the periosteum. Another explanation is that EMH results from transforming of embryonal rests of osteogenic tissue into hematopoietic one under stress conditions in order to maintain sufficient red cell production.

14. Intrathoracic EMH is most often silent, discovered by chance. In rare cases, it can compress neighboring organs and leads to clinical signs such as symptoms of spinal cord compression, dyspnea, cough or pleuritic chest pain.

15. Radiographic exams are useful for recognizing the diagnosis. The chest X-ray shows smooth lobulated masses located at the posterior mediastinum without bony erosion. On computed tomography scanning, intrathoracic EMH appears as unilateral or bilateral well circumscribed, paravertebral masses, lying between vertebra T6 and T12 and having soft tissue density with homogeneous contrast enhancement . These masses contain sometimes adipose tissue .calcification is rare .

16.   chest CT scan : A.  (pre-contrast) and  B  .(post-contrast) shows lobulated paravertebral masses with mild enhancement, linear calcification foci (arrow) and areas of fat attenuation within (*). A small  pleural effusion  (#) can be seen in both sides.

17. Technetium 99m -labeled sulfur colloid scan is also a noninvasive technique of detecting areas of EMH; this radioactive agent is taken up by reticuloendothelial cells. The diagnosis of EMH can be established on the basis of radiographic features especially when they occur in a patient with a long history of anemia. Although, if the diagnosis is not certain or if complications require surgical intervention, biopsy is mandatory. Care should be taken because of high risk of bleeding.

18. Treatment of EMH remains controversial and it is generally required only in the presence of complications such as spinal cord compression, massive hemothorax or recurrent pleural effusion. Low-dose radiation, repeated blood transfusions, surgery, corticosteroids and recently hydroxyurea therapy are the main therapeutic tools allowing the inhibition of hematopoiesis and the decrease of recurrence.

19. Thank you