Multiple endocrine neoplasia 2B presenting with pseudo-Hirschsprung's disease.

Multiple endocrine neoplasia type 2B (MEN 2B) is a rare syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and typical phenotypic features, such as marfanoid habitus, multiple mucosal ganglioneuromas and thickened corneal nerves. Individuals with MEN 2B may develop megacolon and pseudo-obstruction due to intestinal ganglioneuromatosis simulating Hirschsprung's (HSCR) disease. We hereby describe the clinical and genetic features of a 21-year-old male patient with MEN 2B associated with pseudo-HSCR disease. The patient had MTC, pheochromocytoma, marfanoid habitus, multiple mucosal ganglioneuromas, thickened corneal nerves and severe gastrointestinal involvement. Emergent laparotomy was performed when he was presented with acute bowel obstruction. The myenteric and submucosal nerve plexuses in the small and large intestines were composed of diffusely hyperplasic, disorganized, mature ganglion cells. Genetic testing revealed a de novo ret proto-oncogene germline mutation in codon 918 in exon 16. Megacolon and pseudo-obstruction similar to the HSCR disease may develop in patients with MEN 2B. However, the observed dysmotility is the result of an abnormal proliferation of intramural ganglion cells in contrast to the absence of enteric ganglia which were present in the HSCR disease. Attentiveness about the phenotypic characteristics and unusual findings might lead to early and correct diagnosis of the MEN 2B syndrome. This approach improves the survival rate and quality of life considerably.