Primary cutaneous histiocytic sarcoma: A report of five cases with primary cutaneous involvement and review of the literature.

INTRODUCTION: Histiocytic sarcoma is an extremely rare hematologic malignancy of histiocytic origin. Five cases of primary cutaneous histiocytic sarcoma are presented. MATERIALS AND METHODS: Cases of primary cutaneous histiocytic sarcoma were identified using a natural language search from the dermatopathology data base of Cornell University. RESULTS: There was a male predominance (4 males and 1 female) ranging in age from 33years to 92years (mean age of 73years); all presented with a solitary nodule which involved the head and neck area in four and thigh in one. The 73-year-old male had chronic myeloproliferative disorder. Biopsies showed a nonepitheliotropic dermal-based atypical large cell histiocytoid appearing infiltrate dermis showing positivity for common leukocyte antigen, CD4, CD14, CD68, CD163, CD2, CD11c, and lysozyme. Markers of terminal histiocytic differentiation such as S100, langerin, MXA, and CD83 were not seen. In two of the cases there was evidence of extracutaneous dissemination. The treatment in three of the cases was wide excision; there was no evidence of recurrent or metastatic disease. One case was given palliative radiation; the patient died. The other patient with underlying myelodysplastic syndrome died within a few weeks of initial cutaneous presentation. CONCLUSION: HS must be differentiated from other malignant histiocytoid lesions. Staining for common leukocyte antigen and CD163 are the most reliable markers allowing this distinction. Patients who present with primary involvement of the skin may have a favorable outcome but only if treated relatively early in the course of the disease with complete excision.