Systemic amyloidosis is a disease with poor prognosis, characterized by the deposition of amyloid protein in organs throughout the body. There are few case reports of mediastinal amyloidoma. Herein, we present a case a 75-year-old man who was diagnosed with systemic amyloidosis following the resection of a mediastinal tumor. The patient was referred to our department after follow-up after undergoing coronary artery bypass grafting because he was diagnosed with an anterior mediastinal tumor. Computed tomography (CT) revealed a 5 cm-sized mass with calcification adjacent to the ascending aorta and the left pulmonary artery trunk; Positron emission tomography (PET) revealed only slight accumulation in the mass and lymph nodes. Intraoperative findings showed a smooth yellowish-brown tumor adjacent to the ascending aorta, which was completely resected via thoracoscopy. Immunohistochemistry revealed Aλ amyloidosis, and amyloid deposition was observed in the bone marrow and duodenal biopsies. The patient is currently receiving chemotherapy for systemic AL amyloidosis. Preoperatively, there was a concern that the left internal thoracic artery graft was involved in the tumor, but it was possible to preserve it. There was no recurrence 5 years after surgery. This case highlights the importance of early diagnosis and management of systemic amyloidosis, which may significantly improve prognosis.
