Pelvic extramedullary hematopoiesis.

Extramedullary hematopoiesis is an infrequent cause of thoracic masses. Extrathoracic locations are even less common. We have studied two patients, one with suspected pelvic neoplasm, with technetium-99m sulfur colloid marrow image and transmission computerized tomography. This noninvasive evaluation established the diagnosis of pelvic extramedullary hematopoiesis in both. We recommend a similar diagnostic approach in patients with chronic anemia or other predisposing disease, presenting with a pelvic or abdominal mass.