A case of undiagnosed multiple endocrine neoplasia type 2B (MEN 2B)
KS Myint1, A Wiles1, A Marker2, P Jani3, S Middleton1, VKK Chatterjee1 & M Gurnell1
Multiple Endocrine Neoplasia Type 2B is a dominantly inherited disorder characterised by mucosal neuromas, medullary thyroid carcinoma (MTC), phaeochromocytoma, and intestinal ganglioneuromatosis. We report the case of a 34-year-old woman who presented with chronic diarrhoea. She had a longstanding history of gastrointestinal symptoms including diarrhoea since the age of 7 and had been investigated extensively for over 20 years at three different centres, but no definitive diagnosis was made. At the age of 29, she developed acute large bowel obstruction requiring sigmoid colectomy; histological examination revealed a benign sigmoid colonic stricture and diverticular disease. Three years later, she developed flushing, sweating and palpitations. Further investigation revealed elevated urinary free cathecolamines and a 3cm left adrenal mass. Following laparoscopic surgery, histological examination confirmed the lesion to be a phaeochromocytoma. Thereafter, the diarrhoea persisted and she was referred to our hospital for further evaluation. On examination, she was noted to exhibit dysmorphic facies, mucosal nodules on the tongue and cervical lymphadenopathy. Circulating calcitonin was markedly elevated at 44573 ng/l (0 - 46). She underwent total thyroidectomy with bilateral neck dissection and histological examination confirmed MTC with widespread local dissemination. Review of previous histologies showed intestinal ganglioneuromatosis and adrenal hyperplasia in colonic and adrenal specimens respectively. This combination strongly suggested a diagnosis of MEN 2B and the patient was subsequently shown to be heterozygous for a 'de novo' mutation (M918T) in the RET oncogene. The chronic diarrhoea in this patient may be explained by ganglioneuromatosis which together with phaeochromocytoma suggest the diagnosis of MEN 2B. Patients with MEN 2B should be screened for MTC and considered for prophylactic thyroidectomy at an early age.