13014 Primary cutaneous histiocytic sarcoma

Abstract

We present the case of a 32-year-old African-American man with biopsy-proven primary cutaneous histiocytic sarcoma (PCHS) of the left nasal ala. The lesion had been present for 1.5 years and was asymptomatic. Biopsy of the nodule was originally diagnosed as granulocytic sarcoma, with further investigation revealing PCHS. Here we discuss the challenge of both diagnosis and treatment of a rare tumor on a cosmetically sensitive area without clear guidelines with regard to best-care practices. Histiocytic sarcoma is an extremely rare malignancy arising from mature histiocytes. PCHS is the cutaneous version of the disease, usually presenting as asymptomatic nodules, plaques, or subcutaneous tumors. PCHS localized to the skin confers a favorable prognosis with early intervention. Once metastasized, however, the prognosis is highly variable and treatment involves chemotherapy with possible stem cell transplant. Based on the limited cases reported in the literature, wide local excision is recommended, though specific surgical margins have not been detailed. There is a lack of data regarding the benefit of Mohs micrographic surgery. Biopsy is instrumental in differentiating PCHS from similarly presenting lesions. Histologically, PCHS has a predominantly spindled and pleomorphic appearance with hematoxylin and eosin staining, though monomorphic histiocytic appearance has been reported. High mitotic activity has been described. The phenotypic profile of PCHS includes positivity for CD45, CD2, CD14, CD68, CD163, and CD42. Negative markers include MXA, TCL1, CD30, CD117, CD8, CD34, CD123, CD83, langerin, S100, HMB45, CD3, CD5, CD7, and all B-cell markers.