Intracranial Hematopoiesis in Beta Thalassemia: A Case Series.

Extramedullary hematopoiesis (EMH) is a normal response to failure of hematopoiesis at its normal site i.e., bone marrow. It is a manifestation of many congenital hemolytic anemias and marrow failure secondary to myelodysplastic syndromes. Usually, extramedullary myeloid proliferation occurs in liver, spleen and lymph nodes. However, there are many unusual sites where EMH can occur. The authors report two cases of intracranial extramedullary hematopoiesis in beta thalassemia. In one of these patients, epidural soft tissue was detected along frontal and parietal convexities causing compression of brain parenchyma leading to raised intracranial tension and sagging of brain stem, corpus callosum and herniation of cerebellar tonsils. The other case had a similar but unilateral epidural soft tissue. Expansion of diploic spaces of skull was seen in both these cases. As myeloid proliferation is slow, it presents with subtle symptoms of headache and gradually progressive lower limb weakness. A high index of clinical suspicion coupled with imaging findings is the only way to confirm the diagnosis.