RESUMEN
A multiple endocrine neoplasia type 2B(MEN2B) is the most distinct and aggressive form of the MEN type 2 variants. We report a case of a 24-years-old woman with MEN2B. The patient had previously undergone a Duhamel's operation due to a megacolon at 6 years old, minor surgery to remove small tumors on the lip at 8 years old, and a bilateral osteotomy of the femur, due to coxa valga, at 15 years old. She underwent a total thyroidectomy and neck dissection, due to a growing thyroid nodule, despite thyroxine treatment, at 19 years old. The pathology revealed a medullary thyroid carcinoma. There was no history of MEN 2B in her family. She had prominent lips, multiple oral mucosal masses, and marfanoid habitus. During the subsequent follow-up, a positron emission tomogram was taken due to a persistently high level of serum calcitonin, despite repeated neck dissections, which revealed a mass in the right adrenal gland. Adrenomedullary function tests showed high levels of urinary catecholamine metabolites, and a genetic analysis of the peripheral leukocyte showed a codon 918 mutation (Met918Thr) at exon 16 of the RET proto-oncogene. The patient underwent a right adrenalectomy and the pathology revealed a pheoch-romocytoma.