Clinical, molecular and radiological characteristics of thyroid nodules with somatic DICER1 mutations in adults.

[BACKGROUND] Information regarding DICER1-related thyroid tumors in children has accumulated; however, the clinical, molecular and radiological characteristics of thyroid nodules with DICER1 mutations in adults are largely unknown, especially those with somatic mutations.

[OBJECTIVE] In this study, we sought to find clinical, molecular and radiological characteristics of thyroid diseases with somatic mutations in the DICER1 gene in adults.

[PATIENTS] Patients (n = 21) aged ≥18 years with somatic DICER1-related thyroid tumors were enrolled.

[DESIGN] From 1,289 patients who underwent genotyping for PTC-associated variants, 21 patients with 23 DICER1-related thyroid tumors and confirmed somatic DICER1 variants were selected and analyzed for clinical, molecular and radiographic features.

[RESULTS] Somatic DICER1 variants were found in 21 of 1,289 (1.63%) patients with thyroid nodules in this study. All patients were female predominant. Eleven (11/23) were classified as benign and eight (8/23) were malignant, one was a follicular tumor of uncertain malignant potential (FT-UMP) with suspicious capsular invasion and three were under follow-up, in 23 DICER1-related nodules. Eleven nodules (11/23) had other pathogenic gene mutations (RAS and BRAF), and biallelic DICER1 mutations had a high prevalence, about 34.8% (8/23). Ten nodules (10/20) were combined with other tumors with non-DICER1 mutations. No patients had any local invasion or distant metastasis during follow-up. All DICER1-related nodules lacked unique sonographic features, but had the typical appearance of benign or malignant nodules on ultrasound (US).

[CONCLUSION] Somatic DICER1-mutated thyroid nodules in adults usually represent a distinct class of low-risk neoplasms, although they may be accompanied by variants in other thyroid cancer-related genes.