Endocrine Abstracts

Introduction: Pituitary adenomas represent 95% of all sellar masses. Spindle cell oncocytoma (SCO), a rare histopathological entity (0.4% of all sellar tumours), clinically presents as a non-functional pituitary adenoma. According to WHO 2016 Classification of Tumours of the CNS it is a Grade l tumour, but prognosis remains uncertain since recurrence is frequently seen among the few cases reported.

Clinical case: A 59 year-old man presented with progressive fatigue, loss of libido and visual blurring for 5-years. He had pale and hairless skin and on visual field assessment a bitemporal hemianopsia was diagnosed. Hormonal evaluation confirmed low testosterone and gonadotrophins as well as central hypothyroidism and hypocortisolism. PRL and IGF1 levels were normal. MRI scan revealed a T1 and T2 isointense 29×17×17 mm sellar mass with suprasselar extension causing optic chiasm compression. Transsphenoidal surgery removed a grossly bleeding tumour. Histopathological examination revealed a neoplasm composed of interlacing fascicles of spindle cells with eosinophilic and oncocytic cytoplasm. Tumour cells had moderate nuclear atypia and 2 mitotic figures per 10 HPF (Ki67/MIB-1 Proliferation Index 2–5%) were identified. The immunohistochemistry profile was Vimentin/S100/GFAP/EMA/Synaptophysin positive. The final diagnosis was SCO. Visual acuity and Goldmann perimetry improved significantly, but hypopituitarism persisted. MRI scan, 3 months after surgery, showed a contrast enhanced 9×6×11 mm solid intrassellar mass – normal pituitary tissue or residual tumour? Reassessment is scheduled in the next 3 months.

Commentary: An apparent total resection of a SCO was obtained. However, prognosis is difficult to predict due to the short time of follow-up. Presence of cytological atypia and mitosis in this case and knowledge of frequent recurrence rates obeys to a stringent follow-up. The histogenesis of SCO remains unsolved. According to the latest genetic data, SCO and granular cell tumour of the sellar region (GCTSR) may be variants of another rare tumour, the pituicytoma.