This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Which of the following joint is characteristically involved in RA. - \nSelect and explain. \nA. Spine, B. Sacroiliac joint, C. Metacarpophalangeal joint and proximal interphalangeal joint, D. Wrist joint', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Rheumatoid arthritis (RA)\xa0 \xa0 \xa0 \xa0\xa0\xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0 \xa0\n\nRA is a chronic multisystem disorder that may affect many tissues and organs but principally attacks the joint, producing a nonsuppurative proliferative and inflammatory synovitis that often progresses to destruction of the articular cartilage and ankylosis of the joint.\nSymptoms usually develop in the small joints of the hands, (i.e. metacarpophalangeal & proximal interphalangeal\xa0joint), and feet (metatarsophalangeal & interphalangeal) joint.\n\nArticular manifestations in rheumatoid arthritis.\n\nRheumatoid arthritis can affect any of the synovial joints.\nMost commonly the disease starts classically in the joints of hand and feet i.e. PIP, MCP and MTP with the involvement of large joints occurring later.\n\nA. The hands\n\nThese are the major site of involvement in almost all patients with rheumatoid arthritis.\nOf particular importance is the sparing of the distal interphalangeal joint.\nMost commonly the disease starts in the proximal interphalangeal joint. (PIP), and metacarpophalangeal\xa0joint (MCP).\n\nDeformities seen with hand involvement\n\nSwan Neck deformity\xa0\xa0→ hyperextension of PIP joint.\nButtonhole deformity\xa0→\xa0hyperextension of MCP joint.\n\nB. The Feet\n\nMetatarsophalangeal joints are particularly involved in almost all cases of rheumatoid arthritis and are second only to hand involvement.\n\nC. Wrist\n\nInvolved in most patients; radial deviation is the rule.\n\nD. Large Joints\n\nInvolvement of large joint (knee, elbows, hips and shoulders is common but occurs somewhat later than small joint).\n\nSymmetric involvement of the joint is also an important feature of articular involvement in rheumatoid arthritis. The radiological hallmark of rheumatoid arthritis is:\n\nJuxtaarticular osteopenia\nBone erosions\nNarrowing of joint space from loss of articular cartilage\xa0(this is typical of any inflammatory arthritis).', 'role': 'assistant'}]