Primary Histiocytic Sarcoma of Brain-Illustration of Two Cases with Varied Histomorphological Features.

Histiocytic sarcoma (HS) is an aggressive hematolymphoid malignancy that arises from non Langerhans histiocytes and usually involves the skin, lymph nodes, and intestine. The involvement of the central nervous system (CNS) is a rare occurrence with around 30 cases being reported in English literature. Morphological and immunohistochemical evidence of histiocytic differentiation is essential for diagnosis. Prognosis is very poor and consensus on treatment is not available mainly due to its rarity. We report two cases of HS with varied clinical presentation and pathological findings and elucidate the diagnostic challenges of this rare entity.