Pituitary Neuroendocrine Tumor (PitNET)

P. Aarthi¹, Vigneshvarprashanth Umapathy²,*

¹Staff nurse, Kauvery Hospital, Tennur, Trichy, India

²Resident Internal Medicine, Kauvery Hospital, Tennur, Trichy, India

*Correspondence: [email protected]

MRI brain – Pituitary gland enlargement measuring 1.1cm noted.
Endoscopic transnasal transsphenoidal surgery – a surgical instrument is placed through the nostril and alongside the nasal septum to access a pituitary tumor [1].
Histopathology of resected tumor specimen – Section studied showed fragments of a neuroendocrine neoplasm. Tumor is composed of cells arranged in nests, papillae, and acinar pattern. The cells show mild anisonucleosis, having a round nucleus, stippled chromatin, and amphophilic cytoplasm. Mitosis is inconspicuous. No apoplectic change. HPE suggestive of pituitary neuroendocrine tumor.
Post-op CT brain – Postoperative changes with areas of hemorrhage in the pituitary fossa.

Case Presentation

A 57-year-old lady, known to have type-2 diabetes mellitus and hypertension revealed a history of headache for three years and 2 episodes of seizure over the last two years. She was managed symptomatically in a local hospital. She also revealed a history of being treated for hyponatremia a couple of times in the last 2 years. Due to the recurrence of symptoms, an MRI brain was done, which revealed a sellar lesion – pituitary gland enlargement measuring 1.1cm (Image A). Differential diagnoses of pituitary macroadenoma and craniopharyngioma were considered. Surgery was suggested. However, she came to our hospital for further management. General examination did not reveal any significant finding and eye examination did not reveal a visual field defect. Thyroid hormones, growth hormone, cortisol, follicle-stimulating hormone, luteinising hormone, and prolactin were all within normal range. Endoscopic transnasal transsphenoidal resection of the pituitary tumor (Image B) was done. There were no procedural or post-procedural complications. Resected tumor specimen was sent for histopathology (HPE) (Image C) which showed fragments of neuroendocrine neoplasm suggestive of pituitary neuroendocrine tumor (PitNET). Immunohistochemistry for hormonal markers and transcription factors was advised. Pituitary adenomas account for approximately 10% of all intracranial neoplasms and 30-50% of all pituitary region masses. Pituitary adenomas present either due to hormonal imbalance (both microadenomas and macroadenomas) or mass effect on adjacent structures (macroadenomas), classically the optic chiasm. Pituitary adenomas and pituitary carcinomas are in fact neuroendocrine tumors and gradually the terminology is shifting to pituitary neuroendocrine tumors (PitNET). In the 5th edition (2021) of the WHO classification of CNS tumors, “PitNET” has been added to a pituitary adenoma (rather than replacing it) and it is almost certain that the 5th edition of the WHO classification of tumors of endocrine organs will adopt this new terminology as well [2].