Spindle Cells Oncocytoma and Rathke’s Cyst; A Collision Sellar Tumor– Brief Communication & Case Report

Abstract

Collision tumors comprising of pituitary adenomas with other sellar neoplasms are rare. Histological examination is necessary since preoperative studies cannot guarantee an accurate diagnosis. A 66-year-old man with headache and progressive visual alterations, MRI showed a sellar tumor that was diagnosed as pituitary adenoma and graduated as HV IIIc. He underwent surgery and two lesions were resected, one on the cavernous sinus and the other one in sellar region. The lesion of the venous sinus corresponds to a cyst covered by a ciliated pseudostratified epithelium that was diagnosed as Rathke's cyst, and the second one was formed by a neoplastic lesion of elongated cells with focal cellular atypia in a sarcomatous pattern, forming fascicles alternating with a pattern formed by medium eosinophilic cells predominantly in elongated cells in a stroma with abundant sinusoids. For immunohistochemistry, the epithelium of the cyst was PTTG-1, cytokeratin 6/8, and chromogranin positive, while the other lesion was positive chromogranin, FSH, LH PTTG-1, TTF-1, while the spindle cells area was positive immunoreaction for PTTG-1, GFAP, S-100, and VIM and weak expression for TTF-1. These histologic and immunohistochemical findings are suggestive of spindle cells oncocytoma and Rathke cyst, is a rare sellar collision tumor. The expression of TTF-1 in the spindle cell oncocytoma with the idea of common histogenesis for pituicytoma and SCOs and raise the possibility of more aggressive growth in SCOs as compared to pituicytoma.