Which JIA subtype is often RF negative and associated with nail pitting and dactylitis?

• A. Rheumatoid arthritis
• B. Psoriatic JIA
• C. Systemic JIA
• D. Enthesitis-related JIA

Answer: (B)

Nail changes with finger swelling point to psoriatic involvement in juvenile arthritis. Nail pitting is a common clue of psoriasis, and dactylitis (diffuse swelling of an entire finger or toe) is a hallmark feature of psoriatic arthritis. In children with psoriatic JIA, many cases are RF negative, which helps distinguish it from other JIA subtypes.

Other subtypes tend to show different patterns: systemic JIA usually presents with fever and rash; enthesitis-related JIA features enthesitis and often HLA-B27 positivity with axial involvement; RF-positive polyarticular JIA resembles adult rheumatoid arthritis but lacks the distinctive nail changes and dactylitis seen in psoriatic disease.

So, when you see RF negativity together with nail pitting and dactylitis in a child with arthritis, psoriatic JIA is the most likely diagnosis.