Identification of Micro-Recurrent Lesions Using Methylene Blue for Mediastinal Ectopic Parathyroid Adenoma: a Case Report

Background Mediastinal ectopic parathyroid adenomas are rare, and several methods are used to diagnose and localize them preoperatively. Technetium-99m methoxy isobutyl isonitrile scintigraphy has been used to diagnose parathyroid tumors. However, it is difficult to identify tumors buried in adipose tissue during surgery. Case presentation We report a case in which methylene blue effectively identified small recurrent lesions in a mediastinal ectopic parathyroid adenoma. After intravenous injection of methylene blue prior to surgery, the stained parathyroid adenoma was easily identifiable. Additionally, we identified other small recurrent lesions that could not be confirmed on preoperative imaging using real-time in vivo imaging guidance during surgery. Using this strategy, complete macroscopic resection can be performed during video-assisted thoracic surgery. Conclusion Preoperative intravenous methylene blue injection is useful for identifying small recurrent lesions, even in cases of mediastinal ectopic parathyroid adenoma with suspected recurrence.