Endocrine Abstracts

Background: Spindle cell oncocytomas (SCOs) are rare, benign primary tumours of the posterior pituitary gland, characterized by a proliferation of spindle-shaped cells. They are low-grade non-neuroendocrine neoplasms and are often diagnosed as non-functioning pituitary adenomas until the immunohistochemistry shows the characteristic findings, lack of pituitary hormone immunoreactivity and lineage-specific transcription factors.

Case: We report the case of a 66-year-old female who presented with adrenal insufficiency and was found to have bitemporal hemianopia. Pituitary MRI confirmed a pituitary lesion with chiasm compression. She was confirmed to have panhypopituitarism. Her case was discussed in the pituitary multidisciplinary team meeting, with radiologically appearances of a pituitary adenoma. The patient underwent trans-sphenoidal resection of the tumour. Intraoperatively the lesion appeared typical of an adenoma. Part of tumour was left behind as adherent to the posterior diaphragma sellae. Histopathology showed a SCO, neoplastic cells had positive immunoreactivity for TTF-1, focal expression of EMA and negative expression of pituitary transcription factors (SF1, T-Pit, Pit-1). The Ki-67 proliferation index was 15 to 20%. Further characterisation by DNA methylation studies confirmed the histopathological diagnosis. Vision improved after surgery. Post-operative MRI showed a left sided sellar residuum but the large bulk of tumour removed decompressing the optic chiasm. 6 monthly surveillance scans showed no growth of the tumour.

Conclusions: SCOs of the pituitary are rare tumours mostly presenting with progressive symptoms of pituitary dysfunction and or mass effects, particularly visual disturbances. Most reports indicate a peak incidence in the fifth and sixth decades. Early diagnosis and surgical resection are key to improve patient outcomes. Histopathological evaluation remains crucial for confirming the diagnosis. Imaging features are nondescript. Surgical resection is the treatment of choice in most of cases, although hypervascularity and adherence can hinder complete excision. Radiotherapy is reserved for recurrences. Despite a generally favourable prognosis, recurrence necessitates long-term follow-up.