Thyroid Follicular Cell-derived Carcinomas in a Background of Multiple Adenomatous Nodules Leading to a Diagnosis of PTEN Hamartoma Tumor Syndrome in an Adult Patient With a Novel RECQL4 Mutation

Abstract

Background: Phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome (PHTS) is a complex disorder. Carriers develop hamartomatous tumors, with an increased risk for developing malignant tumors in multiple organs. Surveillance to facilitate the early detection and treatment of malignancies is extremely important.

Case report: A 31-year-old male presented with a 10 cm left lobe thyroid gland mass. After fine needle aspiration a left hemithyroidectomy was performed, which demonstrated a minimally invasive follicular thyroid carcinoma (FTC, stage pT3a) and microscopic classical papillary thyroid carcinoma (PTC) in the background of about 50 separate adenomatous nodules (0.2-5 mm). Immunostaining showed loss of PTEN protein in the minimally invasive FTC and in all of the nodules tested, with uninvolved parenchyma serving as an internal control. Kaiser Permanente Northern California (KPNC) Hereditary Cancer Panel, testing for 62 genes, was performed and showed germline mutations in PTEN and RecQ like helicase 4 (RECQL4) genes. Completion thyroidectomy subsequently performed demonstrated about 60 follicular cell-derived adenomatous nodules (0.3-10 mm). Genetic counseling and evaluation documented Cowden syndrome (CS) in the family. Thus, PHTS was confirmed.

Conclusion: This report documents synchronous FTC and PTC in a background of multiple follicular adenomatous nodules with a novel RECQL4 mutation in an adult patient with PHTS. As such, documented the loss of PTEN protein in a thyroid gland affected by multiple adenomatous nodules aided in diagnosing PHTS.

Keywords: Cowden syndrome; Minimally invasive follicular thyroid carcinoma; PTEN gene mutation; PTEN hamartoma tumor syndrome; RECQL4 gene; germline mutation; surveillance.