Background: For many years, lateral, aberrant thyroid tissue in adults was a term used almost exclusively for metastatic thyroid carcinoma. However, aberrant, benign ectopic thyroid tissue does occur, and it is most commonly found as a part of the evaluation of endocrine dysfunction. Rarely, aberrant, benign ectopic thyroid presents as a primary mass.
Case report: We present a 35-year-old female who presented for removal of a lifelong posterior lateral neck nodule.
Results: Histologic examination and immunohistochemical studies confirmed the presence of aberrant, benign ectopic thyroid tissue. The patient had no endocrine problems, and she had a normally located and functioning thyroid gland.
Conclusions: This case illustrates that not all aberrant thyroid tissues in adults are malignant or associated with endocrine disorders. This case also illustrates the rare association of ectopic thyroid and a normally located and functioning thyroid gland. In this patient, a somatic mutation in a transcription factor important in thyroid migration could explain these findings.