Thyroid Carcinoma with Pulmonary Metastasis, Confirmed by the Detection of Thyroglobulin in Bronchoalveolar Lavage Fluid

A 34-year-old man with diffuse bilateral lower lung fields nodular shadows was admitted to our hospital. Twenty years ago, right half of his thyroid had been resected on a diagnosis of thyroid carcinoma. Bronchoalveolar lavage as well as transbronchial lung biopsy (TBLB) were performed to obtain a definite diagnosis on the pulmonary lesions. Bronchoalveolar lavage revealed an appreciable amount of thyroglobulin, which was highly suggestive of metastasis of thyroid carcinoma to the lung. This was confirmed by the pathological examination on the specimen obtained by TBLB, which revealed hyperchromatic cells originating from follicular type thyroid carcinoma. Since little thyroglobulin is expected to exist in the normal lung tissue, this study may indicate that detection of thyroglobulin in BALF should be very helpful for confirming pulmonary metastasis of thyroid carcinoma.