Sellar Solitary Fibrous Tumor Mimicking Pituitary Adenoma: Diagnostic Pitfalls, Contemporary Pathological...

Background/Objectives: Sellar solitary fibrous tumors (SFTs) are exceptionally rare mesenchymal neoplasms that frequently mimic non-functioning pituitary adenomas (PAs) because of overlapping clinical manifestations and nonspecific radiological findings. Consequently, preoperative diagnosis remains challenging and definitive diagnosis relies on histopathological and immunohistochemical evaluation. Methods: We report a sellar SFT initially diagnosed as a PA and analyze the diagnostic features of previously reported cases to identify recurring diagnostic pitfalls. Clinical, endocrinological, radiological, intraoperative, histopathological, and immunohistochemical findings from a patient with a sellar SFT were retrospectively reviewed. A structured literature review of previously reported sellar SFTs was performed to compare presenting symptoms, endocrine abnormalities, imaging characteristics, pathological findings, and diagnostic features. Results: A 65-year-old man presented with headache, progressive visual impairment, fatigue, and anterior hypopituitarism. Magnetic resonance imaging demonstrated a heterogeneously enhancing sellar lesion with suprasellar extension and cavernous sinus involvement, leading to an initial diagnosis of non-functioning PA. Endoscopic transsphenoidal surgery revealed an unexpectedly hypervascular and firm tumor. Histopathological examination demonstrated a spindle-cell neoplasm with a hemangiopericytoma-like vascular pattern, six mitoses per 10 high-power fields, absence of necrosis, and diffuse nuclear STAT6 positivity, establishing the diagnosis of CNS WHO grade 2 solitary fibrous tumor according to the 2021 WHO classification. Review of the literature demonstrated that most sellar SFTs share similar clinical and radiological features with PAs and are diagnosed only after surgical resection. Conclusions: Sellar SFT should be considered in the differential diagnosis of atypical sellar masses despite the absence of characteristic imaging findings. Recognition of intraoperative features, together with appropriate immunohistochemical evaluation, particularly STAT6 staining, is essential for accurate diagnosis. Current evidence remains insufficient to define the optimal postoperative management of completely resected sellar SFTs, emphasizing the importance of individualized treatment decisions and long-term surveillance.