Extramedullary hematopoiesis: a rare occurrence in the sinonasal tract.

Extramedullary hematopoiesis (EMH) is a systemic reaction to inadequate hematopoiesis. We report two exceedingly rare cases of EMH involving the paranasal sinuses. The first patient, a 30-year-old man, presented with a maxillary sinus mass. The lesion was excised by endoscopic surgery: definitive histology identified foci of EMH within an inflammatory fibromyxoid pseudotumor. The second case occurred in a 29-year-old man affected by intermediate beta-thalassemia. He was hospitalized with a diagnosis of sphenoid sinus mucocele secondary to an ethmoid lesion. The patient underwent endoscopic excision of the mass and drainage of the sphenoid mucocele. At definitive histology, a diagnosis of EMH was established. Herein, the presenting modalities, imaging profile, and treatment options of this rare EMH localization are reviewed.