Ectopic intrapulmonary thyroid tissue mimicking metastatic tissue.

Background: Ectopic intrapulmonary thyroid is extremely rare, with only about two cases reported in the literature. These cases were found either during the work-up of a solitary pulmonary nodule or at autopsy. Here, we report a case of ectopic intrapulmonary thyroid mimicking multiple pulmonary metastases from an endometrioid adenocarcinoma of the uterus.

Patient Findings: A 50-year-old woman presented with dysmenorrhea and menorrhagia. Endometrial curettage of the uterus revealed an endometrioid adenocarcinoma. During the staging, multiple pulmonary nodules were found. To exclude the possibility of lung metastases of the endometrioid adenocarcinoma from the uterus, video-assisted thoracic surgery (VATS) with wedge resection was performed for the largest nodule. The histopathology for that nodule was entirely consistent with normal thyroid tissue. The patient underwent surgery for uterine cancer and was discharged without further adjuvant chemotherapy. The remaining intrapulmonary nodules were unchanged in size on a serial computed tomography scan.

Summary: In this patient, pulmonary metastases were initially considered the most likely cause of the multiple pulmonary nodules, but the diagnosis of the ectopic intrapulmonary thyroid was ultimately made based on VATS-wedge resection for the largest pulmonary nodule. The patient was able to avoid any unnecessary systemic chemotherapy.

Conclusions: Ectopic intrapulmonary thyroid is extremely rare but can be confused with pulmonary metastases from other sites. We are unaware of similar cases in the literature.