Endocrine Abstracts

Introduction: Pituitary tumours especially Cushing’s disease is extremely rare to present in Lynch syndrome. The pathophysiology behind the disease is complex and patients with MSH 2 variant tend to have aggressive tumours in the form of corticotroph carcinomas or invasive non-functional pituitary adenomas.

Case Report: 62-year-old gentleman known to have Lynch syndrome (MSH-2 variant) was waiting for reversal of his stoma due to right hemicolectomy for colonic malignancy done in late 2023. He later presented to emergency around April 2024 with worsening of heart failure. He was offloaded with diuretics which unmasked his cushingoid features. On examination, he is afebrile, with blood pressure of 140/80 mm Hg, pulse of 100/min. His bloods showed refractory hypokalaemia. His random cortisol was 700 nmol/l with testosterone of 2.9 nmol/l, FSH of 0.7 iu/L and LH of <0.1 iu/l. He was subjected to 24 hours urinary cortisol which showed elevated cortisol levels of 358 nmol/24 hrs and 578 nmol/24hrs on two occasions. He had later undergone low dose dexamethasone suppression test which yielded a level of 391 nmol/l showing biochemical evidence of Cushing’s syndrome. His ACTH level was also high 168 ng/L which was unusual. His MRI pituitary revealed pituitary mass of 1.5 x0.7x1.1 cms. He had PET scan which showed no evidence of any ectopic tumour or metastatic disease. He was discussed in pituitary MDT with outcome of Transsphenoidal hypophysectomy. He underwent the operation with postop cortisol level < 50 nmol/l showing recovery. Histological report confirmed corticotroph adenoma.

Conclusion: The link between Pituitary Cushing’s disease and lynch syndrome is rare and only few case reports have showed its existence. One report showed evidence of MSH-2 variant lynch syndrome with corticotroph carcinoma. Ours was a benign pituitary corticotroph adenoma with no evidence of any metastasis.