Extramedullary hematopoiesis: A report of two cases

Abstract

Extramedullary hematopoiesis (EMH) is defined as hematopoiesis occurring in organs outside of the bone marrow. The present report describes two cases of thalassemic patients with paraspinal medullary hematopoiesis and analyzes the clinical manifestations, imaging, pathology, diagnosis and treatment of EMH. In addition, a supplementary review of previously published cases is provided along with a review of the related literature. Computed tomography (CT) of the first case revealed multiple paraspinal masses, and the largest was 6.2×8.0 cm in diameter. Likewise, CT of the second patient revealed multiple paraspinal masses in the bottom of the left thoracic cavity, and the largest was measured 10.1×10.5 cm. The two cases underwent surgical biopsy and the findings were compatible with a diagnosis of EMH. In conclusion, EMH is a compatible and rare disease, and should be distinguished from other neoplasms. EMH must considered when masses with characteristic radiologic appearance are detected in patients with thalassemia intermedia.

Spinal Cord Compression due to Extra Medullary Hematopoiesis in a Case Of Thalassemia Minor

“…Para spinal location of EMH has been noted in 11-15% cases. [4][5][6][7] However Koch et al reported para spinal location in only 0.6% cases of EMH. [8] Even amongst these, around 80% remain asymptomatic, detected incidentally on radiological imaging.…”

“…Various theories that explain presence of EMH in para spinal region include presence of hematopoiesis in this region during fetal development that gets reactivated due to hematological stress, direct extension of hematopoietic material from medullary cavity of vertebrae, embolism and development of hematopoietic tissue from branches of intercostal veins. [1,4,5] Thoracic and lumbar regions are most frequently affected. The exact cause for this is not known, however it adds to the morbidity as the spinal canal is quite narrow here.…”

“…However it is also known to occur in other organs like pleura, adrenals, breast, thymus, kidneys, gastrointestinal tract, intracranial structures, retroperitoneal tissue, sweat glands, prostate, broad ligaments, peripheral nerves, heart, retroperitoneal fat, Para spinal regions. [1,2,5] . Para spinal location of EMH has been noted in 11-15% cases.…”

“…[8] Even amongst these, around 80% remain asymptomatic, detected incidentally on radiological imaging. [4][5][6] The importance of para spinal EMH is that it tends to form pseudotumors behaving like a SOL and causing SCC that has considerable morbidity. Various theories that explain presence of EMH in para spinal region include presence of hematopoiesis in this region during fetal development that gets reactivated due to hematological stress, direct extension of hematopoietic material from medullary cavity of vertebrae, embolism and development of hematopoietic tissue from branches of intercostal veins.…”

“…[1,[3][4][5] EMH is commonly seen in organs involved in hematopoiesis in fetal life like liver or in organs of reticuloendothelial system like spleen and lymph nodes. However it is also known to occur in other organs like pleura, adrenals, breast, thymus, kidneys, gastrointestinal tract, intracranial structures, retroperitoneal tissue, sweat glands, prostate, broad ligaments, peripheral nerves, heart, retroperitoneal fat, Para spinal regions.…”