Primary Intracranial Melanocytic Tumor Simulating Pituitary Macroadenoma: Case Report and Review of the Literature

Abstract

Primary intracranial melanocytic tumors are rare lesions, sellar ones being even more exceptional. So far, six melanomas and two melanocytomas have been described in an intrasellar and/or suprasellar location. We report on the case of a 25-year-old Caucasian woman presenting with a 4-year history of amenorrhea and an intrasellar mass with suprasellar extension suggestive of a pituitary macroadenoma. A gross subtotal resection of a hemorrhagic tumor was performed. Histological examination revealed melanin-laden pleomorphic tumor cells that tested positive for HMB-45 and S-100 and negative for cytokeratins, thus demonstrating that the tumor was a melanocytic neoplasm. An extensive workup failed to find evidence of any other primary site. The patient received no further treatment and is alive and well after 24 months of follow-up. Primary sellar melanocytic neoplasms are extremely rare lesions and present with few differential diagnoses. Deciding whether the tumor is best classified as a melanocytoma or a melanoma may prove difficult. Wide histological variations in both melanocytomas and melanomas render careful consideration of the clinical, radiological, and gross features essential in distinguishing one from the other.