Case history: A 63-year-old female presented with bi-temporal hemianopia. Pituitary MRI demonstrated a macroadenoma with suprasellar extension. Her medical history included a glomus tumour of the right ear treated with external beam radiotherapy (EBRT) 25 years previously. She had no evidence of pituitary hormone abnormality and had normal urinary metanephrines levels. She underwent transsphenoidal surgery with total resection and full recovery of her visual fields. Immunohistochemistry demonstrated a null cell pituitary adenoma. Recurrence developed 5 years later.
Investigations: Histology showed an atypical null cell tumour, Ki67 was 10%, MGMT methylation negative, with unusual features of widespread cytoplasmic vacuolisation and negative SDHB staining. Genetic testing revealed a heterozygote pathogenic missense SDHB mutation.
Results and treatment: On follow-up MRI a new extra axial cerebellar lesion at the foramen magnum was visible, with extension into the left hypoglossal canal and an intradural extra medullary cervical lesion at the level of C3/4. Both were initially thought to be metastatic deposits from the previous paraganglioma, but histology of the cerebellar lesion demonstrated a metastatic deposit from a pituitary carcinoma, composed of large extensively vacuolated cells; with positive immunostaining for cytokeratin MNF116, LMW cytokeratin, synaptophysin and pituitary transcription factors SF-1, and negative for pituitary hormones, TTF1, EMA and S-100 protein.
Conclusions: Pituitary carcinoma is a very rare phenomenon, accounting for only 0.1% of all pituitary tumours. SDHB mutations are known to have a higher risk of developing aggressive and malignant paragangliomas, with figures reported as high as 30%; thought to be due to the higher prevalence of extra adrenal paragangliomas. Other tumours such as GIST, renal cell carcinoma and thyroid papillary carcinoma are recognised in these patients; as well as links to pituitary adenomas. However, here we describe, the first case of pituitary carcinoma in a patient with a germline SDHB mutation.
01 Jan - 31 Dec 2017
Society for Endocrinology