Fine needle aspiration of splenic extramedullary hematopoiesis presenting as a solitary mass. A case report

BACKGROUND: Extramedullary hematopoiesis (EMH) generally occurs in patients with deficient bone marrow hematopoiesis secondary to either peripheral red cell destruction or marrow replacement. EMH is most commonly seen in the liver and spleen as a diffuse lesion. Rarely EMH presents as a solitary mass, posing a diagnostic dilemma. In asymptomatic patients without obvious evidence of hematopathology, the differential diagnosis is even more complex. Despite the several articles detailing the radiographic findings in EMH, fewer promote the utility of fine needle aspiration (FNA) in making this diagnosis. CASE: EMH presented as a discrete, 6-cm, tumorlike splenic mass, first identified on computed tomography in a patient with a history of prostate carcinoma. FNA findings suggested a diagnosis of EMH, which was confirmed by splenectomy. In searching for the cause of EMH, no evidence of either metastatic or hematologic disease was identified. The cause of EMH in this patient remains unknown. To our knowledge, this is the first case of solitary splenic EMH reported to occur in an asymptomatic patient. CONCLUSION: FNA is a useful adjunct in the evaluation of isolated splenic masses, particularly in the diagnosis of EMH, where hematopoietic precursors are readily identified cytologically. We advocate the use of FNA in the management of splenic masses. In addition, our case also suggests that EMH be included in the differential diagnosis of isolated splenic lesions, even in patients without obvious hematologic disorders.