Diagnostic and prognostic biomarkers of a sellar melanocytic tumor mimicking pituitary adenoma: case report and literature review

Primary or metastatic melanocytic tumors in the sellar region are rare and can pose a diagnostic challenge. Here we describe a case of a 74-year-old man who underwent radiological investigations for a transient episode of blurred vision. Based on the clinical and endocrinological findings and MRI results, the patient was assumed to have a clinically non-functioning pituitary macroadenoma, which was followed-up over a 2-year period. He did not have any endocrine symptoms or progressive visual deterioration, and no history of past malignancy, including melanoma. Endocrinological investigation was unremarkable; blood hormone levels were within the normal ranges except for low serum total testosterone and bioavailable testosterone levels without symptoms of hypogonadism. The longitudinal MRI follow-up demonstrated a gradual increase in the size of the tumor over the course of 11 months. For this reason, the patient underwent surgery. Pathologic examination including histology, immunohistochemistry and electron microscopy achieved the correct diagnosis of melanocytic tumor of the sellar region morphologic examination is essential in the diagnosis of melanocytic tumors. Hmb-45 is an important diagnostic biomarker in melanocytic lesions. The use and exploration of miRNA, Ki67 and osteopontin are important in understanding the genesis, progression, and prognosis in treatment of patients with melanocytic tumors.