A Case of Abdominal Aortic Retroperitoneal and Mesenteric Amyloid Light Chain Amyloidoma

We report the case of a Japanese woman with amyloid light chain (AL) amyloidoma in the abdominal aortic retroperitoneum and mesentery. Irregular soft tissue mass lesions with calcification in the abdominal aortic retroperitoneum and mesentery were initially detected by computed tomography at another hospital. The lesions gradually compressed the duodenum, causing symptoms of bowel obstruction. The patient was clinically diagnosed with retroperitoneal fibrosis, and prednisolone was administered at a dose of 40 mg/day. However, the lesions did not change in size and her symptoms continued. She was transferred to our hospital and underwent mesenteric biopsy for histopathology using abdominal laparotomy. The histopathological and immunohistological findings of the mesenteric specimen demonstrated lambda light chain deposition. Accordingly, the patient was finally diagnosed with AL amyloidoma with no evidence of systemic amyloidosis. After laparotomy, her general condition worsened because of complications of pneumonia and deep vein thrombosis. She died suddenly from acute myocardial infarction. We have concluded that abdominal aortic retroperitoneal and mesenteric AL amyloidoma may have very poor prognoses in accordance with previous reports. In addition, the size and location of AL amyloidoma directly influence the prognosis. We suggest that early histopathology is important for improving prognosis.