DICER1 syndrome and thyroid disorders

Abstract Introduction DICER1 syndrome is an inherited genetic disorder caused by mutations in the DICER1 gene that predisposes to the development of several tumours. The thyroid is often affected. Follicular nodular disease, usually presenting in childhood or adolescence, is the most common manifestation. DICER1 mutation carriers also have an increased risk of developing thyroid cancer. To increase the awareness of the disorder, we present two case reports: Method - Result A 13-year-old girl without hereditary predisposition, presented with a multinodular goitre. Ultrasound showed nodules of varying size and echogenicity; cytology showed Bethesda II. At age 15, after further growth and suspicion of teratoma, a diagnostic hemithyroidectomy was performed. Histopathological findings of follicular nodular disease with a striking heterogeneity raised the suspicion of DICER1 syndrome, later confirmed by sequencing of both tumoral and germline DNA. After genetic counselling, an individualized surveillance program was initiated. The mutation was defined as de novo. Two years later, the remaining thyroid lobe was removed due to local symptoms. Histopathology was benign. A 17-year-old boy was screened after being diagnosed with DICER1 mutation carriership, having a sister diagnosed with DICER1 syndrome. Ultrasound showed multiple nodules, one defined as EU-TIRADS 4 and Bethesda IV, respectively. A diagnostic hemithyroidectomy revealed a 55 mm widely invasive differentiated high grade thyroid carcinoma. After completing supplementary hemithyroidectomy, clearance of central compartment and radioiodine treatment the patient is followed according to the national thyroid cancer follow up program as a high-risk patient. Discussion This report highlights the importance of interdisciplinary care, genetic counselling and personalized surveillance strategies.