Multiple Endocrine Neoplasia Type 2B (MEN2B) delayed diagnosis: importance of opportune recognition of MEN2 Syndromes in pediatric thyroid cancer

ABSTRACT Background: RET proto-oncogene mutations are responsible for familial thyroid medullary carcinoma and multiple endocrine neoplasia (MEN) type 2A and 2B. These syndromes develop specific biomarkers and, in the case of MEN2B, clinically observable stigmas. However, the diagnosis of patients with MEN2B is usually delayed. Because of the close genotype-phenotype correlation, molecular testing is the final approach for the diagnosis to establish preventive care and therapeutic behaviors. Discussion: pM918T is classified as ''highest risk'' for medullary carcinoma with a 50% of lifetime risk for developing pheochromocytoma. Most cases of MEN2B are due to a de novo mutation. Even with the increased risk of developing pheochromocytoma, our 24-year-old patient does not yet present one. Other factors may be involved in the modulation of the phenotype in different populations. Case report: We present the case of a woman diagnosed with a thyroid nodule at the age of nine. She underwent a total thyroidectomy plus radical cervical lymph node dissection, with a diagnosis and initial management of papillary thyroid carcinoma. During the evolution of the disease, she developed pulmonary metastases. At the age of 24, after her first endocrinological evaluation, typical physical manifestations of MEN2B were observed. A re-evaluation of the original thyroidectomy revealed a medullary carcinoma, with positive manifestation CEA and calcitonin. The analysis of RET proto-oncogene identified a de novo mutation in exon 16 (pM918T). Conclusion: The timely diagnosis of MEN2B offers opportunities to make appropriate preventive and therapeutic decisions that may change the natural evolution of the disease and its complications.

Neoplasia endócrina múltipla tipo 2 / Multiple endocrine neoplasia type 2

O termo neoplasia endócrina múltipla tipo 2 (NEM 2) foi sugerido em 1968, por Steiner e cols., para diferenciar a síndrome clínica caracterizada pela presença de carcinoma medular de tireóide (CMT), feocromocitoma e hiperparatireoidismo, então denominada síndrome de Sipple, da síndrome de Wermer ou NEM tipo 1, que acomete as glândulas paratireóides, pâncreas e hipófise. Sizemore e cols. (1974) complementaram a diferenciação através da classificação da NEM 2 em 2 subgupos: pacientes com CMT, feocromocitoma, hiperparatireoidismo e aparência normal (NEM 2A) e pacientes sem acometimento das paratireóides e fenótipo caracterizado por ganglioneuromatose intestinal e hábitos marfanóides (NEM 2B). CMT é usualmente o primeiro tumor a ser diagnosticado. O diagnóstico do CMT determina que seja avaliada a extensão da doença e rastreamento do feocromocitoma e hiperparatireoidismo. O diagnóstico de CMT esporádico ou hereditário é realizado através da análise molecular do proto-oncogene RET. Neste artigo são discutidos os aspectos fisiopatológicos, as anormalidades genéticas e os aspectos clínicos da NEM 2. A abordagem diagnóstica e terapêutica nos indivíduos afetados, carreadores assintomáticos e familiares em risco também são discutidos. Os avanços relacionados ao rastreamento genético e intervenção precoce permitiram uma melhoria no prognóstico a longo prazo. No entanto, ainda não dispomos de tratamento eficaz para doença metastática.