Atypical Psoriatic Arthritis Presenting as Presumed Septic Monoarticular Arthritis

Area of Science:

• Rheumatology
• Infectious Diseases
• Dermatology

Background:

• Psoriatic arthritis (PsA) is a chronic inflammatory disease associated with psoriasis.
• Monoarticular presentation of PsA is uncommon, often posing diagnostic challenges.
• Distinguishing PsA from infectious arthritis is critical for appropriate management.

Observation:

• A woman presented with monoarticular knee swelling and sterile joint fluid with neutrophilic leukocytosis.
• Repeat joint aspiration revealed Candida parapsilosis, initially suggesting fungal arthritis.
• Despite antifungal therapy, symptoms progressed, and new skin lesions appeared on the palms.

Findings:

• The patient was ultimately diagnosed with psoriatic arthritis, despite initial presentation mimicking infection.
• The case underscores the importance of considering PsA in atypical presentations, even with positive fungal cultures.
• Skin manifestations, though delayed, were key to the final diagnosis.

Implications:

• This case highlights the diagnostic complexity of psoriatic arthritis, particularly in its early monoarticular phase.
• It emphasizes the need for a broad differential diagnosis, including inflammatory and infectious etiologies.
• Timely recognition and appropriate immunosuppressive therapy are crucial for managing psoriatic arthritis effectively.