Cytologic features of pigmented atypical meningioma mimicking melanoma on intraoperative crush preparations.

Pigmented tumors rarely arise in the meninges, and when they do, these are mainly melanocytomas or melanomas. We describe the cytologic findings of atypical meningioma with intratumoral hemosiderin pigment mistaken for spindle cell melanoma in a 33-year-old male patient during intraoperative consultation. Preoperative radiologic images revealed a cystic meningeal mass with intratumoral hemorrhage. The crush preparation demonstrated cellular smears of syncytial clusters as well as fascicles of large pleomorphic spindle cells with discrete cytoplasmic brown pigment. Detection of cytoplasmic brown pigment and a preponderance of large spindle cells with nuclear pleomorphism led to a diagnosis of spindle cell melanoma on intraoperative cytology. Histopathologic examination displayed high cellularity, nuclear pleomorphism with prominent nucleoli, and foci of spontaneous necrosis. In addition, there were areas showing classic meningotheliomatous meningioma features. Altogether, the histologic findings were consistent with atypical meningioma. The cytoplasmic pigment in the tumor cells was confirmed to be hemosiderin using special stains and immunohistochemistry. To the best of our knowledge, this is the first case report describing cytomorphology of atypical pigmented meningioma. We discuss the differential diagnosis in intraoperative cytology and a possible mechanism related to intratumoral hemosiderin deposition in meningiomas. Diagn. Cytopathol. 2015;43:149-152. (c) 2014 Wiley Periodicals, Inc.