[Papillary thyroid carcinoma in a child with congenital dyshormonogenetic hypothyroidism. Case report].

INTRODUCTION: Papillary thyroid carcinoma (PTC) is a rare childhood disease. The development of PTC in dyshormonogenetic congenital hypothyroidism (CH) is infrequent, with very few case reports in literature.

OBJECTIVE: To report a case of PTC in a boy with dyshormonogenetic CH without goitre and exposed to ionising radiation. To evaluate relationships between these factors and development of PTC.

CASE REPORT: We present a boy with dyshormonogenetic CH since birth. Early hormonal substitution was initiated, with subsequent normal levels of thyrotropin and thyroid hormones. He has also congenital cardiomyopathy, exposed to interventional treatment with 10 heart catheterisations, and approximately 26 chest X-rays at paediatric doses. A thyroid nodule was found in thyroid echography at the age of 6 years old. Fine needle aspiration biopsy confirmed high probability of thyroid carcinoma (Bethesda 5). The pre-surgical thorax and cerebral scan showed no evidence of metastasis. The patient underwent total thyroidectomy. Pathological examination revealed a 0.5cm papillary thyroid micro-carcinoma in the right lobe, with no evidence of dissemination.

CONCLUSION: Genetic mutations and radiation exposure may play an important role in the development of PTC. There may be common pathways between dyshormonogenetic CH and thyroid carcinoma that need further investigation.