Aim: In patients with multiple myeloma, extramedullary myeloma manifestations can occur alongside bone marrow infiltration and osseous involvement. The aim of this study was to describe extramedullary myeloma manifestations using B-mode ultrasound and contrast-enhanced ultrasound. Material and methods: Between February 2006 and 2021, a total of 21 patients with multiple myeloma and histologically or clinically proven extramedullary myeloma manifestations (n = 24) were included. All patients underwent B-mode ultrasound and contrast-enhanced ultrasound of extramedullary myeloma manifestations. B-mode ultrasound patterns of location, size border characteristics, and echogenicity (hypoechoic/isoechoic or hyperechoic) as well as contrast-enhanced ultrasound enhancement (hyper-, iso-, or hypoenhancement) were analyzed. Results: In most cases, extramedullary myeloma manifestations were located in the chest wall (n = 11; 45.8%). In all 24 cases, extramedullary myeloma manifestations were hypoechoic on B-mode ultrasound. N = 16 (66.6%) of extramedullary myeloma manifestations had smooth and n = 8 (33.3%) had irregular borders. The mean lesion size was 5.4 cm. On contrastenhanced ultrasound, extramedullary myeloma manifestations presented arterial hyper- (n = 20; 83.3%) or isoenhancement (n = 4; 16.7%) followed by parenchymal iso- (n = 1; 4.2%) or hypoenhancement (n = 23; 95.8%). In molecular genetic analysis, every patient with reliable FISH results tested positive for at least one aberration considered “high-risk”. Conclusion: Extramedullary myeloma manifestations were typically hypoechoic on B-mode ultrasound. On contrast-enhanced ultrasound, they presented characteristic arterial hyperenhancement followed by parenchymal washout. All patients studied for the genetic risk status were found to be “high-risk”.

multiple myeloma; extramedullary myeloma manifestation; ultrasound; vascularization; CEUS