Mediastinal Ectopic Parathyroid Adenoma in a Patient Followed for Colon Cancer and Chronic Renal Failure: A Challenging Case.

Colorectal cancer is a significant cause of morbidity and mortality worldwide. The advances in early diagnosis and treatment have increasingly expanded the patient population surviving from colorectal cancer. Herein, we present a case of a patient with mediastinal ectopic parathyroid adenoma who has been followed up for postoperative colon cancer. The patient is a 59-year-old man with postoperative colon cancer and chronic renal failure in whom control positron emission tomography/computed tomography revealed multiple bone metastases. However, on methylene-diphosphonate bone scintigraphy, multiple involvement with increased uptake was associated with renal osteodystrophy/hyperparathyroidism; technetium-99m 2-methoxyisobutylisonitrile parathyroid scintigraphy was performed, which revealed mediastinal ectopic parathyroid adenoma. To the best of our knowledge, this is the first case report in the literature reporting the co-occurrence of colon cancer, chronic renal failure, and ectopic parathyroid adenoma.