Clinicopathological features and endoscopic findings of spindle cell oncocytoma: A case report and review of the literature

INTRODUCTION AND IMPORTANCE: Spindle cell oncocytoma (SCO) of the pituitary gland is very difficult to differentiate from other pituitary neoplasms and is often misdiagnosed based on imaging procedure features. We report a rare case of SCO arising from the neurohypophysis and suggest a useful diagnostic criterion for accurate diagnosis and surgical pitfalls. CASE PRESENTATION: A 53-year-old man was admitted to our hospital with slight headache and diplopia. Neuroimaging revealed pituitary tumour in the suprasellar and sellar regions with speckled gadolinium enhancement on T1-weighted magnetic resonance imaging, as a so-called blooming artefact. The enhanced anterior pituitary gland was located anteriorly. Computed tomography (CT)-scan demonstrated an isodense mass without calcification showing strong contrast enhancement with iodine contrast medium. Laboratory findings showed no abnormalities. Subtotal resection of the tumour was achieved by an endoscopic endonasal transsphenoidal approach. Histological examinations showed spindle-shaped to epithelioid tumour cells featuring eosinophilic and granular cytoplasm staining strongly for anti-mitochondrial antibody and thyroid transcription factor 1. The tumour was therefore diagnosed as SCO, belonging to tumours of the posterior pituitary. Headache and diplopia were disappeared immediately postoperatively, and follow-up at 12 months demonstrated no signs of recurrence. CLINICAL DISCUSSION: SCO of the pituitary gland is a rare tumour that originates from the neurohypophysis and is difficult to diagnose on routine neuroimaging procedure. CONCLUSION: Accurate diagnosis requires careful identification of clinical signs, neuroimaging features including contrast-enhanced CT, and analysis of combined results from morphological and immunohistochemical evaluation of tumour tissue.