Magnetic resonance imaging findings of paracoccidioidomycosis in the musculoskeletal system

ObjectiveTo describe magnetic resonance imaging (MRI) findings in musculoskeletal paracoccidioidomycosis (PCM). MethodsRetrospective case series study after IRB approval. Two musculoskeletal radiologists reviewed in consensus the MRI findings of 11 patients with microbiologically and/or pathologically proven osteoarticular PCM. The MRI evaluation included discrimination of abnormalities in joints, bones and soft tissues. ResultsMean age of patients was 29years (10-55years), eight men and three women. Musculoskeletal involvement was the only or the primary presentation of the disease in seven patients (63%). Osteomyelitis was the most common presentation, with seven cases (63%). Primary arthritis was found in one patient (9%). Isolated extra-articular soft tissue PCM was found in three patients: myositis (2) and subcutaneous infection (1). All cases showed regions with signal intensity higher than or similar to the signal of muscle on T1-weighted images. Penumbra sign was present in five cases (45%). T2-weighted images showed reactive soft tissue oedema in eight cases (72%). Post-gadolinium images showed peripheral (8/9) or heterogeneous (1/9) enhancement. Synovial enhancement was present in all cases of joint involvement (6/6). Lipomatosis arborescens was documented in one case of chronic knee involvement. ConclusionTo our knowledge, this is the first case series describing MRI findings of musculoskeletal PCM. Musculoskeletal involvement was the primary presentation of the disease in most cases, and therefore, neoplasms were initially in the differential diagnosis. Osteomyelitis was the most common presentation, often with secondary involvement of joint and or soft tissue.