Multiple endocrine neoplasia type 2B (MEN2B) diagnosis: a case report.

Background: Multiple endocrine neoplasia type 2B (MEN2B) is a rare autosomal dominant syndrome characterized by medullary carcinoma of the early thyroid, pheochromocytoma, and non-endocrine manifestations, such as marfanoid habits and other skeletal abnormalities as well as mucosal neuromas and ganglioneuromatosis of the gastrointestinal tract.

Case description: A 10-year-old male began follow-up at our service at 3 years of age through pediatric gastroenterology due to intestinal constipation. The mother also reported that the child had painless lesions on the tip of the tongue since birth with progressive worsening. The patient simultaneously began follow-up with pediatric endocrinology due to low gains in weight and height, between which only isolated low weight was found, and the onset of follow-up with the pediatric neurology team due to longstanding headache combined with vomiting, photophobia, and phonophobia as well as a specific reading and writing disorder. The patient was sent to clinical genetics. The child's karyotype was 46, XY (normal). Through a physical examination, the pediatric neurology team identified joint hypermobility, important muscle hypotrophy, gingival hypertrophy, and lipodystrophy. The patient was sent to neurogenetics, initiating a set of general laboratory exams for the investigation of the lipodystrophy and a panel of exams for lipodystrophy, neuropathy, and muscle hypotrophy as well as electroneuromyography. MEN2B due to genetic mutation was confirmed and the patient was sent to the pediatric endocrinology clinic for follow-up. Currently 10 years of age and again with the pediatric endocrinology team for the diagnosis of MEN2B, the investigation of pheochromocytoma and medullary thyroid cancer was initiated.

Conclusions: An additional mutation occurs in most cases of MEN2B. The diagnosis is only established when the child or, in most cases, adolescent presents with medullary thyroid cancer in an advanced and even metastatic stage. However, non-endocrine manifestations, can lead to an early diagnosis and timely intervention. The diagnosis of MEN2B is made with the confirmation of the autosomal dominant genetic mutation or a mutation of the RET gene. In the absence of these mutations, the majority of clinical manifestations should be present.