A Rare Case of Metastatic Adenocarcinoma Involving a Parathyroid Adenoma

The second population infiltrated the center of the nodule and showed a pseudopapillary architecture and anastomosing cords composed of markedly pleomorphic cells that were positive for cytokeratin 7 (CK7) and thyroid transcription factor-1 (TTF-1) on immunohistochemical (IHC) staining. The most common site of origin were breast, leukemia, melanoma, and lung.2,3 One potential explanation for this is the high blood flow through parathyroid glands, which is typical of endocrine organs. A total of 7 previous cases of metastasis to parathyroid adenomas have been reported in the English literature. 2 While there is a report of lung adenocarcinoma to parathyroid hyperplasia, to our knowledge there is only 1 other case reported of lung adenocarcinoma with metastasis to a benign parathyroid adenoma. 4 Metastases to the parathyroid glands are probably under-recognized in patients with widely metastatic disease.2,3 In most cases, these metastases are not clinically important.