Abstract
Histiocytic sarcoma is a rare malignant neoplasm of hematopoietic origin composed of cells showing morphologic and immunophenotypic evidence of histiocytic differentiation. We describe the 2nd case of primary histiocytic sarcoma of the cavernous sinus/Meckel’s cave, and the 8th case involving the CNS. A 61-year-old Caucasian man presented with numbness on the entire left side of his face, shooting pain in the left frontal region, and headaches. Imaging revealed an enhancing extra axial soft tissue mass located in the left cavernous sinus and left Meckel’s cave. Diagnosis was established through open biopsy, after failed attempts via CT-guided trans-foramen ovale fine-needle aspiration biopsy and keyhole biopsy. The tumor was composed of large non-cohesive epithelioid cells invading nerves and ganglion cells. Tumor cells were immunopositive for CD68, CD163, and immunonegative for the anaplastic large cell lymphoma marker ALK-1 as well as other lymphoid, myeloid, and dendritic cell markers. Histiocytic sarcoma has strong potential for systemic spread; early diagnosis and treatment are important. Our patient was initially treated with radiation therapy but subsequently developed metastases. © 2014, The Japan Society of Brain Tumor Pathology.