Multimodal imaging diagnosis of multiple myeloma with renal involvement: a case report

Extramedullary renal involvement secondary to multiple myeloma (MM) is extremely rare and prone to preoperative misdiagnosis. Its clinical and imaging manifestations have not been systematically summarized, leading to frequent preoperative misdiagnosis. To summarize the multimodal imaging characteristics and clinical diagnostic value of MM with renal involvement through a typical case report, so as to improve the understanding and early recognition rate of this disease.

A 67-year-old male patient with left lumbodorsal pain was examined by multimodal imaging. Ultrasound and contrast-enhanced ultrasound suggested a malignant retroperitoneal mass adjacent to the left kidney. Computed tomography showed extensive invasion of the left renal lesion. Emission computed tomography indicated significantly decreased left renal function. ¹⁸F-Fluorodeoxyglucose positron emission tomography-computed tomography identified systemic multi-site involvement. Pathological biopsy confirmed anaplastic plasma cell tumor. The patient was finally diagnosed with light-chain MM complicated with renal involvement (Durie-Salmon Stage IIIB, R-ISS Stage III high-risk) and received multi-line chemotherapy, but died of severe infection 5 months after diagnosis.

Multimodal imaging plays an irreplaceable role in the accurate diagnosis, lesion evaluation, and biopsy guidance of MM complicated with renal involvement. It can effectively reduce misdiagnosis and provide important evidence for clinical treatment and prognosis assessment.