Extramedullary hematopoietic ascitic fluid cytology in myelofibrosis

A patient having myelofibrosis with myeloid metaplasia complicated by ascites is reported. Cytologic examination of the Papanicolaou-stained smears of the ascitic fluid revealed megakaryocytes and granulocytes of varying maturity, including eosinophils and reactive mesothelial cells. Autopsy examination demonstrated extensive involvement of the omentum and peritoneal surfaces by extramedullary hematopoiesis. The most likely mechanism of the ascites is multicentric ectopic extramedullary hematopoiesis with exfoliation of the characteristic cells into the peritoneal space.