Multiple myeloma-associated iliopsoas muscular amyloidoma first presenting with bilateral femoral nerve entrapment

We report a 38-year-old man of multiple myeloma with bilateral femoral nerve entrapment caused by bilateral huge protruding masses in the inguinal areas. The masses were identified as iliopsoas muscular amyloidoma after the operation. He was diagnosed with multiple myeloma 1 year ago before he was admitted to our hospital. He complained of muscle weakness in the bilateral thigh and protruding lumps in the bilateral inguinal areas with tenderness for 6 month. The pelvic MRI revealed round masses in the iliopsoas muscles of bilateral inguinal areas. To implement the nerve decompression, the resection of the bilateral masses was done. The pathological result showed Congo red-positive substance with green birefringence to polarized light in a dense fibrous background. Before the operation, six cycles of chemotherapy with VAD (vincristine, adriamycin, dexamethasone) and two cycles of chemotherapy with PAD (bortezomib, adriamycin, dexamethasone) regimen were performed. One month after the operations, one cycle of chemotherapy with PADT (bortezomib, adriamycin, dexamethasone, thalidomide) regimen was used and the patient reached complete remission. The function of the bilateral femoral nerves restored to normal 7 months after the operation with a Karnofsky score of 100. Twenty-two months follow-up showed that there was no evidence of the recurrence of the iliopsoas muscular amyloidoma and no progression of multiple myeloma.