In which of the following condition, proximal interphalangeal joint is involved and distal interphalangeal joint is spared?
**Core Concept**
The question is testing the student's knowledge of rheumatological disorders that affect the joints, specifically the involvement of the proximal interphalangeal (PIP) joint and the sparing of the distal interphalangeal (DIP) joint.
**Why the Correct Answer is Right**
The correct answer is Rheumatoid Arthritis (RA). In RA, the PIP joints are commonly involved, leading to swelling, pain, and stiffness. This is due to the autoimmune nature of the disease, which causes inflammation and damage to the synovial tissue of the joints. The involvement of the PIP joints is a hallmark feature of RA, whereas the DIP joints are typically spared. This distinction is important in differentiating RA from other types of arthritis, such as osteoarthritis, which often affects the DIP joints.
**Why Each Wrong Option is Incorrect**
**Option A:** Psoriatic Arthritis (PsA) - In PsA, both the PIP and DIP joints can be involved, and the disease often presents with a more asymmetrical pattern of joint involvement.
**Option B:** Osteoarthritis (OA) - While OA typically affects the DIP joints, it can also involve the PIP joints, especially in advanced cases.
**Option C:** Gout - Gout typically affects the DIP joints, particularly the first metatarsophalangeal joint, and is less likely to involve the PIP joints.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the involvement of the PIP joints and the sparing of the DIP joints are key features that distinguish Rheumatoid Arthritis from other forms of arthritis.
**Correct Answer:** C.