Endocrine Abstracts

Multiple Endocrine Neoplasia 2 (MEN2) is a rare, autosomal dominant neuroendocrine tumour. MEN2A is a syndrome of medullary thyroid carcinoma (MTC), pheochromocytoma and parathyroid tumours. MEN2B is characterised by MTC, pheochromocytoma, marfanoid habitus and intestinal & mucosal ganglioneuromas. MEN2 syndromes are due to mutations in the RET proto-oncogene, located near the centromere of the chromosome 10. While the commonest mutations described in MEN2A is in exon 11 (codon 634), they are almost exclusive to exons 15 & 16 in MEN2B. We report a man who presented with pheochromocytoma and characteristic marfanoid habitus.

This 25-year-old Caucasian man presented with 5-year history of headache, nausea, palpitation and hypertension. He was thin, 1.93m tall with an arm span of 2.01m. He also had high arched palate, archnodactyly, increased joint mobility and history of dental crowding. However, he did not have lens dislocation or cardiac malformations on ECHO cardiography. Family history revealed that his father has marfanoid habitus and his brother has been undergoing investigations for hypertension in Canada. No other family history suggestive of MEN syndromes. His 24-hour urinary free noradrenaline output was 11611 nmol (Normal range: 0-800) and free adrenaline output was 5642 nmol (NR: 0-100), suggesting pheochromocytoma. His CT scan of abdomen showed 7cm right adrenal mass, which showed avid uptake of MIBG. He underwent laproscopic adrenalectomy and the histology confirmed pheochromocytoma.

In view of his marfanoid habitus, he was initially screened for MEN2B mutations (M918T in exon 16 & A883F in exon 15), which were negative. Subsequent sequencing of the RET proto-oncogene showed mutation at codon 634 (TGC - TAC) in Exon 11. This is suggestive of MEN2A and the marfanoid habitus is likely to be a family trait. Subsequently, his Calcitonin was found to be very high at >1500 ng / L (NR: 0 - 4.6) and is awaiting thyroidectomy.