Juxta-articular soft-tissue mass

Common: Abscess; Aneurysm; Arteriovenous fistulas; Baker cyst; Bunion; Bursal fluid collection; Bursitis; Calcific tendonitis; Ganglion; Gouty tophus; Hemarthrosis; Joint effusion; Myositis ossificans; Neuropathic arthropathy; Osteoarthritis; Periarticular calcification; Synovial cyst; Synovial hypertrophy secondary to arthritis; Synovial osteochondromatosis
Uncommon: Amyloidosis; Articular chondroma; Calcium pyrophosphate dihydrate crystal deposition disease; Giant cell tumor of tendon sheath; Hydatid disease; Juxtaarticular myxoma; Lipoma; Lipoma arborescens; Localized nodular synovitis; Meniscal cyst; Multicentric reticulohistiocytosis; Neuroma; Para-articular chondroma; Parosteal chondrosarcoma; Parosteal osteosarcoma; Perilabral cyst; Pigmented villonodular synovitis; Synovial hemangioma; Synovial sarcoma; Tumoral calcinosis; Xanthoma