A Review of Thyroid Rests: From Embryology to Clinical Management

Ectopic thyroid tissue (ETT) is a rare developmental anomaly often misidentified as other pathologies like parathyroid adenomas or metastatic lymphadenopathy. This can lead to unnecessary surgical interventions and diagnostic delays. This narrative review aims to synthesize current knowledge on the embryological origins, anatomical distribution, diagnostic challenges, and management strategies of ETT. A comprehensive literature search was conducted by searching PubMed, Google Scholar, and Scopus databases, covering publications from January 2015 to January 2025. Fifteen peer-reviewed publications, including case reports, case series, reviews, and original research, were selected for inclusion. Ectopic thyroid tissue (ETT) most commonly manifests as a lingual thyroid, situated at the base of the tongue. Diagnosis is challenging due to overlapping imaging characteristics with neoplastic or hyperfunctioning parathyroid tissue. A multimodal approach is essential, combining imaging (ultrasound, CT, MRI) with functional assessments (scintigraphy) and histological confirmation (FNA). Management is individualized, with observation for asymptomatic cases and surgical intervention for symptomatic or suspicious lesions. A multidisciplinary team (MDT) approach is critical for accurate diagnosis and to prevent unnecessary procedures. This review underscores the importance of structured diagnostic protocols to improve outcomes for patients with ETT.