Primary Epithelioid Angiosarcoma of Bone with Robust Cell Cycle Progression and High Expression of SPARC: A Case Report and Review of the Literature.

Epithelioid angiosarcoma of bone is a rare entity. Secreted protein acidic and rich in cysteine (SPARC), or osteonectin, is a secreted glycoprotein that has been implicated in tumorigenesis. We report a case of epithelioid angiosarcoma involving the long bones of the lower extremity showing diffuse and strong expression for SPARC immunohistochemistry in tumor cells. Ki-67 was positive in ~50% of tumor cell nuclei and the accompanying mitotic index was 19 mitotic figures/10 high power fields.Expression of SPARC in tumors has been correlated with sensitivity to nanoparticle albumin-bound paclitaxel (Nab-paclitaxel), particularly in the context of robust cell cycle progression into the mitotic phase. This finding could suggest new therapeutic options for further consideration.