Melanoma of the sellar region mimicking pituitary adenoma

Abstract

We report here the case of an 82-year-old woman who presented with visual disturbance. MRI demonstrated a sellar mass. The diagnosis of pituitary adenoma was made. She underwent transnasal surgery. Histologic, immunohistochemical and ultrastructural studies indicated that the tumor was a melanoma. Despite an exhaustive search for a primary lesion elsewhere, none was found. The sellar tumor was considered a primary lesion, although extrasellar primary tumor imaging cannot be excluded with 100% certainty. Reported examples of melanoma affecting the sellar region are few. They exhibit morphologic features identical to those of melanomas arising elsewhere. Although very rare, primary melanomas enter into the differential diagnosis of sellar lesions.

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

“…Many melanocytes can be found around the floor of the sella, predominately in the meningeal lining, the ventrolateral regions of the medulla oblongata, and around the spinal cord [9,15,17]. Metastatic melanomas represent spread from a primary tumor developing in the skin, or less commonly the lungs, gastrointestinal tract, retina, or other distant sites [4,6,18,19]. Metastatic melanoma usually grows rapidly and has a poor prognosis.…”

“…Of previous reported cases of primary melanocytic tumors of the sella, few reports presented MIB-1/Ki-67 indices. A high MIB-1/Ki-67 index was associated with a more progressive symptomatic course [6,9]. Rousseau et al [15] reported a MIB-1/Ki-67 index of 3% with a 4 year clinical history.…”

“…Sellar melanocytic tumors are immunonegative for synaptophysin, a neuronal and neuroendocrine cell marker, for epithelial cell markers and for pituitary hormones. Of 12 cases of melanocytic tumors of the sella reported previously, immunopositivity for S-100 was reported in 6 cases [3,4,6,7,9,15], vimentin in 3 cases [1,7,15], and other markers such as epithelial membrane antigen (EMA) and Masson-Fontana positivity in various others [1,3,5,15,20]. The most useful marker was Hmb-45, which has high sensitivity and specificity and was positive in 8 cases [1,3,4,[6][7][8][9]15].…”

“…Electron microscopy can provide conclusive results. The presence of melanin granules called melanosomes in the cytoplasm of tumor cells proves that the tumor consists of melanin producing cells [6].…”

“…They may be accompanied by visual deterioration, headache, hemorrhages, diabetes insipidus and decreased adenohypophyseal secretory activity. While surgical resection remains the first line of treatment, total resection of sellar melanocytic tumors is often difficult, and residual tumor can be left behind [1][2][3][4][5][6][7]. Radiation therapy and/or chemotherapy are additional treatment options [3,4,[6][7][8][9][10].…”