Primary cytodiagnosis of peritoneal extramedullary hematopoiesis.

Cytologic examination of peritoneal fluid in a patient with known myelofibrosis and previous splenectomy revealed megakaryocytes along with erythroid and myeloid precursors. These findings were consistent with extramedullary hematopoietic (EMH) implants of the peritoneum. A few similar cases have been occasionally reported in the literature. This case represents an additional example of a primary diagnosis of peritoneal EMH in which therapy was based on the cytologic findings and sequential cytologic observations were made.