[DICER1 mutated, solid/trabecular thyroid papillary carcinoma in an 11-year-old child]. / Carcinome papillaire thyroïdien variante solide/trabéculaire avec mutation DICER1 chez une enfant de 11 ans.

ABSTRACT

We report the case of an 11-year-old patient diagnosed with a solid variant of papillary thyroid carcinoma. Papillary thyroid carcinoma (PTC) is the most common thyroid cancer, representing 80-90% of all newly diagnosed thyroid cancers. Among the many variants described, solid/trabecular variant of papillary thyroid carcinoma is a rare entity and account for 3% of thyroid cancers. It is more common in children and young adults, and it is seen in higher proportion in post radiation papillary thyroid carcinoma cases. Histologically, solid variant papillary carcinoma is characterized by a predominantly solid, trabecular or insular growth pattern, and the presence of cytological features typical of PTC. Its main differential diagnosis is poorly differentiated thyroid carcinoma. It has a less favorable prognosis than the classical papillary type, with a higher risk of distant metastasis, extrathyroidal extension and lympho-vascular invasion. It is associated with a slightly lower long-term survival in adult cases, but not in children. The management of solid variant PTC includes surgery, associated or not with postoperative radioiodine ablation, according to the aggressiveness criteria. Our patient had a DICER1 somatic mutation. Carriers of germline DICER1 mutations are predisposed to a rare cancer syndrome, the DICER1 syndrome, with a higher risk of numerous tumors and infrequently differentiated thyroid carcinomas.