Aspiration biopsy cytology of ectopic thyroid tissue in the lateral chest wall: a case report.

Background Ectopic thyroid tissue is a rare abnormality that mainly occurs in the midline of the neck but also in other unusual locations. Because fine needle aspiration biopsy (FNAB) is a widely used procedure for evaluating head and neck and other palpable masses, sampling of these lesions may be encountered. Case A 66-year-old woman presented with left lateral chest wall mass during follow-up for chronic obstructive pulmonary disease, hypertension and diabetes mellitus. Initial evaluation by FNAB suggested ectopic thyroid tissue, which was confirmed later by tissue biopsy and immunostains. This is the first reported case of ectopic thyroid tissue in the lateral chest wall area. Conclusion Awareness of this abnormality and the possibility of ectopic thyroid tissue in erratic locations will help cytopathologists make the correct interpretation on FNAB sampling.