Bone Marrow Metastasis in a Suspected Case of Angiosarcoma Unravelled by Immunohistochemistry

A 40-year-old female presented with progressive fatigue and left upper abdominal discomfort for 1 month. CT scan revealed ill-defined hypervascular lesions in the liver and diffuse enlargement of the spleen. She had severe anemia with leukoerythroblastic reaction. Bone marrow smears revealed clusters and discrete spindle cells, few plump and round cells. Trephine biopsy revealed an infiltrative spindle-cell neoplasm replacing the marrow with the focal presence of epithelioid cell clusters. On immunostaining, the tumor cells were positive for CD34, CD31, Friend Leukemia Virus Integration-1 (FLI1), and vimentin, consistent with metastatic angiosarcoma. There were multiple small aggregates of 5-10 MIB-1 positive tumor cells (overall positivity < 1%). She succumbed to her illness before initiation of any therapy. Bone marrow metastasis of angiosarcoma is extremely rare. The aggressive clinical course and judicious use of immunohistochemical markers are required for definitive diagnosis.