Abstract
INTRODUCTION AND IMPORTANCE: Ectopic thyroid tissue is an uncommon developmental anomaly, particularly when located in the chest, making its diagnosis and management complex. When hyperthyroidism presents in a patient with a normal cervical thyroid gland, it may obscure the presence of ectopic functioning thyroid tissue, especially in unusual locations like the thoracic cavity. CASE PRESENTATION: We present the case of a 35-year-old female with biochemical evidence of hyperthyroidism but a clinically and radiologically normal thyroid gland in the neck. Further imaging uncovered a chest mass, initially suspected to be malignant. Surgical excision and histopathological analysis confirmed it as ectopic thyroid tissue. Postoperative follow-up showed normalization of thyroid hormone levels, and the patient had an uneventful recovery. CLINICAL DISCUSSION: This case illustrates a rare presentation of hyperthyroidism caused by ectopic thyroid tissue in the absence of cervical thyroid abnormalities. A thorough diagnostic workup is essential to rule out malignancy and confirm ectopic thyroid origin. Surgical resection remains the definitive treatment, often resulting in hormonal normalization. CONCLUSION: Ectopic thyroid tissue should be considered in cases of unexplained hyperthyroidism, especially when the cervical thyroid appears normal. Awareness of this rare condition can prevent misdiagnosis and help guide appropriate therapeutic strategies.