Histiocytic Sarcoma : Epidemiology
Histiocytic sarcoma is exceedingly rare and makes up <0.5% of all hematolymphoid malignancies. It usually occurs in adults, although cases have reported in all age groups. The median age at presentation is 51 years and it appears to have a bimodal distribution (increased frequency below 30 years and over 50 years of age). Associations: Histiocytic sarcoma shows association with non-Hodgkin's lymphomas (lymphoblastic lymphoma, follicular lymphoma, and low-grade B-cell lymphoma) as well as germ cell tumors (mediastinal non-seminomatous germ cell tumors and primary gonadal germ cell tumors). The mediastinal tumors are most commonly malignant teratomas with or without yolk sac component.