Presacral extramedullary hematopoiesis: a diagnostic confusion concerning a rare presentation.

OBJECTIVE To report a rare case of extramedullary hematopoiesis (EMH) with an asymptomatic intrapelvic mass in a patient with thalassemia major. CLINICAL PRESENTATION The patient presented with a pelvic mass discovered by ultrasonography before undertaking laparoscopic cholecystectomy for gallstones. Technetium-99m MDP bone scan failed to differentiate EMH from malignancy. A fine-needle aspiration smear was misdiagnosed when atypical megakaryocytes were interpreted as malignant cells. EMH was suggested by magnetic resonance imaging and confirmed by an ultrasound-guided Tru-Cut biopsy. CONCLUSION This case report illustrates the need to consider EMH in the differential diagnosis of patients with chronic hematological disorders and mass lesions in extramedullary sites.