A 30-year-old male presented with pain and swelling of the knee and the ankle joint of the right side especially at the inseion sites along with burning and pain sensation during micturition, urethral discharge, fever for 2 weeks. Patient also gave a history of multiple episodes of bloody diarrhea 1 week back. O/E. B/L conjunctivitis with oral ulcers Plantar fasciitis Onycholysis and distal yellow discoloration of nails X- ray pelvis with B/L hip was normal. Lab findings revealed raised ESR and other acute phase reactants along with mild anemia and increased HLA B27 titers. Joint aspirate was sterile.

**Core Concept**
The patient's symptoms and lab findings suggest an inflammatory condition affecting multiple systems, including the musculoskeletal, gastrointestinal, and urogenital systems. The presence of HLA B27 titers and certain clinical features, such as plantar fasciitis and onycholysis, are suggestive of a specific autoimmune disorder.

**Why the Correct Answer is Right**
The patient's symptoms and lab findings are consistent with Reactive Arthritis (ReA), a type of seronegative spondyloarthritis. ReA typically follows a gastrointestinal or genitourinary infection, and the patient's history of bloody diarrhea and urethral discharge supports this. The presence of HLA B27 titers is a strong risk factor for developing ReA. The joint aspirate being sterile is characteristic of ReA, as opposed to septic arthritis. The extra-articular features, such as plantar fasciitis, onycholysis, and conjunctivitis, are also typical of ReA.

**Why Each Wrong Option is Incorrect**

**Option A:** This option might suggest a diagnosis of Gout, but the patient's symptoms and lab findings do not support this. Gout is typically characterized by acute, self-limiting episodes of joint pain and swelling, often associated with hyperuricemia and elevated urate levels.

**Option B:** This option might suggest a diagnosis of Rheumatoid Arthritis (RA), but the patient's symptoms and lab findings do not support this. RA is typically characterized by symmetric polyarthritis, elevated rheumatoid factor, and other specific autoantibodies.

**Option C:** This option might suggest a diagnosis of Psoriatic Arthritis (PsA), but the patient's symptoms and lab findings do not support this. PsA is typically characterized by psoriasis, dactylitis, and specific radiographic features.

**Option D:** This option might suggest a diagnosis of Ankylosing Spondylitis (AS), but the patient's symptoms and lab findings do not support this. AS is typically characterized by chronic back pain and stiffness, limited spinal mobility, and elevated HLA B27 titers.

**Clinical Pearl / High-Yield Fact**
Reactive Arthritis is a type of seronegative spondyloarthritis that follows a gastrointestinal or genitourinary infection. The presence of HLA B27 titers and certain clinical features, such as plantar fasciitis and onycholysis, are suggestive of this diagnosis.

**Correct Answer:** D.

✓ Correct Answer: A. Reactive ahritis