Endocrine Abstracts

Spindle cell oncocytoma (SCO) is a rare entity with just 18 cases reported in the literature. It was first described in 2002 and was codified as a separate diagnostic entity in the 2007 WHO classification of brain tumours. SCO is a nonadenomatous sellar neoplasm with rich vascularization and intra and supra-sellar infiltration. Usual clinical presentation consists of headache, visual field defects and pan-hypopituitarism. The preoperative diagnosis is difficult due to a lack of specific imaging and clinical findings.

We report the case of a 65-year-old otherwise healthy man who presented with symptoms of visual blurring for 2 months. Clinically he had a bitemporal hemianopsia and imaging investigation revealed an homogenous supra-sellar tumor with 29×23×31 mm which was clearly delimited from the pituitary and molded the optic chiasm. He was admitted to the neurosurgery unit where he was diagnosed with panhypopituitarism: TSH 0.46 mU/l (0.1–4) with FT₄ 0.65 (0.93–1.7); LH <0.1 UI/l (1–7), FSH 0.4 UI/l (1–12), total testosterone <10 ng/dl (180–750); ACTH <5 pg/ml (9–50), cortisol 0.4 μg/dl (7–25); IGF1 49.5 ng/ml (75–212) and prolactin 29 ng/ml (9–20). The patient underwent a right frontal craniotomy with partial removal of a highly vascular tumor with difficult cleavage plan from the pituitary.

Histological examination revealed a spindled lesion, with positive immunostain for vimentin, epithelial membrane antigen (EMA), synaptophysin, a Ki 67<1% and a negative immunostain for pituitary hormones.

Postoperatively the patient developed and maintained central diabetes insipidus and had partial visual recovery. The brain MRI performed 6 months after surgery showed a reduction in the tumor volume to 21×19×21 mm and a thin optic chiasm.

The authors present the first described SCO case with only supra sellar presentation. This unique characteristic increased the difficulty of an already challenging preoperative diagnosis and may represent an unknown manifestation of SCO biology.