A 7-year-old boy develops abrupt onset of severe obsessive-compulsive symptoms, emotional lability, and motor tics two weeks after a streptococcal throat infection. Which finding would most support a diagnosis of Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS)?

• A Elevated serum ceruloplasmin
• B Positive antinuclear antibodies
• C Elevated anti-streptolysin O (ASO) titers ✓
• D Positive Lyme serology

Explanation

PANDAS requires evidence of preceding Group C streptococcal infection, demonstrated by elevated ASO titers or positive throat culture. ANA suggests autoimmune connective tissue disease. Ceruloplasmin is relevant in Wilson disease. Lyme serology tests for Borrelia burgdorferi, unrelated to streptococcal infection.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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