Differential Diagnosis for Synovial Chondromatosis of the Fourth Proximal Interphalangeal Joint

• Single most likely diagnosis:
  • Synovial chondromatosis: This condition is characterized by the formation of multiple cartilaginous nodules within the synovial membrane of a joint, which can detach and become loose bodies, causing symptoms such as pain, swelling, and decreased range of motion. The appearance described is highly suggestive of this condition due to its characteristic involvement of the joint and the presence of cartilaginous loose bodies.
• Other Likely diagnoses:
  • Osteoarthritis: While primarily a degenerative condition, osteoarthritis can lead to the formation of osteophytes and loose bodies within the joint, which might mimic some aspects of synovial chondromatosis, especially in advanced stages.
  • Rheumatoid arthritis: This autoimmune condition can cause significant joint inflammation and destruction, potentially leading to the formation of loose bodies or nodules within the joint, although the primary presentation and other systemic symptoms would likely differ.
  • Pigmented villonodular synovitis (PVNS): A condition characterized by inflammation of the synovium, leading to the formation of villonodular projections that can cause joint symptoms. While it doesn't typically produce cartilaginous loose bodies, its presentation can sometimes overlap with synovial chondromatosis.
• Do Not Miss diagnoses:
  • Septic arthritis: An infectious process within the joint that can cause rapid destruction and necessitates urgent treatment. While the clinical presentation (e.g., acute onset, fever, significant pain) usually differs from synovial chondromatosis, missing this diagnosis could have severe consequences.
  • Tuberculous arthritis: A form of joint infection caused by Mycobacterium tuberculosis, which can lead to chronic inflammation and destruction of the joint. Its presentation can be subtle and might mimic other forms of arthritis, making it a critical diagnosis not to miss.
• Rare diagnoses:
  • Lipoma arborescens: A rare condition characterized by the replacement of the synovial membrane with mature fat cells, leading to a villous appearance. It's an uncommon cause of joint symptoms and might be considered in the differential for unusual joint pathologies.
  • Synovial hemangioma: A benign vascular tumor of the synovium, which can cause joint symptoms due to its space-occupying effect or associated bleeding. It's a rare condition that might be encountered in the differential diagnosis of joint diseases.