62-year-old male with fever and tenderness. Rule out osteomyelitis. There is serpentine increased signal abnormality within the left femoral head with associated deformity and subchondral collapse consistent with patient's known history of avascular necrosis. Moderate degenerative changes affect the left hip. There is fluid within the left femoral acetabular joint with associated enhancement on postcontrast sequences indicating a synovitis likely related to the aforementioned avascular necrosis. There is diffuse subcutaneous edema about the left thigh most pronounced along the medial and lateral aspect of the thigh with associated skin thickening. There is diffuse increased signal abnormality within the musculature of the left hip and thigh. There is a 12.4 x 8.2 x 24.6 cm (TR X AP X CC) encapsulated collection with fluid signal intensity and internal septation along the anterior aspect of the femoral diaphysis which demonstrates peripheral enhancement on postcontrast sequences, suspicious for abscess formation. There is no definitive increased bone marrow signal abnormality to suggest osteomyelitis of the underlying bone. There is also nonspecific diffuse subcutaneous edema and increased signal abnormality within the musculature of the right thigh as seen on the large field-of-view images. Extensive metallic susceptibility artifact from a right total hip arthroplasty limits evaluation of the right hip. There is a small left knee joint effusion.
1. 24.6 cm encapsulated collection along the anterior aspect of the femoral diaphysis consistent with abscess formation. There is extensive subcutaneous edema and edema type signal abnormality within the musculature of the left thigh also suspicious for cellulitis/pyomyositis. No evidence of osteomyelitis. 2. Avascular necrosis of the left femoral head with associated subchondral collapse/fracture. There is a small left hip joint effusion with enhancement indicating a synovitis, likely related to the aforementioned avascular necrosis.3. Small knee joint effusion.