Subcutaneous ectopic thyroid tissue presenting as a midline neck mass in a middle-aged woman: a rare case report.

Background: Ectopic thyroid tissue is a rare congenital anomaly resulting from abnormal embryological descent of the thyroid gland. Though typically diagnosed in younger individuals, it may occasionally present later in life with variable anatomical locations and clinical manifestations. Case presentation: We report a distinctive case of a 48-year-old female who presented with a progressively enlarging, painless midline neck mass associated with dysphagia and dyspnea. Imaging revealed complete absence of orthotopic thyroid tissue and identified a subcutaneous mass anterior to the cricoid cartilage - a highly unusual location. Fine-needle aspiration and histopathology confirmed ectopic thyroid tissue exhibiting nodular hyperplasia with benign characteristics. Surgical excision was followed by exploration to rule out residual thyroid tissue. Postoperative elevation in serum Thyroid stimulating hormone (TSH) levels confirmed the absence of functional thyroid remnants. Discussion: This case is notable for two uncommon features: the patient's middle age at presentation and the subcutaneous positioning of the ectopic tissue, diverging from the more frequently observed lingual or intramuscular sites. This case is one of the rarely reported cases of subcutaneous anterior-neck ectopic thyroid in an adult and the first with complete absence of orthotopic thyroid tissue in a patient over 45 years old. Conclusion: Clinicians should consider ectopic thyroid tissue - even in older patients and atypical anatomical sites - when evaluating midline neck masses. Preoperative assessments and tailored interventions are essential for preserving thyroid function and achieving optimal outcomes.