Pigmented papillary epithelial neoplasm of the pituitary fossa: a distinct lesion of uncertain histogenesis

Primary pigmented intracranial neoplasms are strikingly uncommon. The differential diagnosis is limited and includes both epithelial and nonepithelial tumors, most of which arise within or near the ventricular system. The authors describe a 42-year-old man who presented with a pigmented papillary epithelial lesion that arose within the sella and exhibited suprasellar extension and bony erosion. Following external beam radiotherapy and multiple surgical resections, tumor growth became rapid, necessitating additional debulking procedures. Pathologic evaluation of subsequent lesional tissue samples revealed an anaplastic lesion with malignant epithelial and spindle cell components. Occasional epithelial cells showed features reminiscent of the original papillary lesion, whereas others exhibited oncocytic morphologic features. This case represents the only report, to our knowledge, of a pigmented papillary epithelial neoplasm arising within the pituitary fossa. Although the histogenesis of this tumor is enigmatic, this appears to be a distinct lesion characterized by aggressive growth and the capacity for anaplastic progression.