Differences between leukemic arthritis and juvenile idiopathic arthritis

Area of Science:

• Pediatric Rheumatology
• Pediatric Hematology-Oncology
• Clinical Diagnostics

Background:

• Juvenile idiopathic arthritis (JIA) is a common cause of chronic arthritis in children.
• Leukemic arthritis (LA), a manifestation of acute lymphoblastic leukemia (ALL), can mimic JIA, delaying diagnosis and treatment.
• Early differentiation between LA and JIA is critical for appropriate patient management.

Purpose of the Study:

• To identify distinct clinical and laboratory features differentiating leukemic arthritis (LA) from juvenile idiopathic arthritis (JIA) at disease onset.
• To develop a model for accurately distinguishing between LA and JIA in pediatric patients.

Main Methods:

• Retrospective analysis of 76 pediatric patients (under 16) diagnosed with probable JIA, including those ultimately diagnosed with ALL (LA) or JIA.
• Comparison of clinical (age, gender, symptoms) and laboratory (blood counts) characteristics between LA and JIA groups.
• Statistical analysis using chi-square, relative risk, Mann-Whitney U, T-test, and binary logistic regression for differentiation.

Main Results:

• Lower mean age at diagnosis and shorter symptom onset time observed in the LA group compared to JIA.
• LA patients exhibited more pronounced systemic symptoms (fever, weight loss, night sweats, hepatosplenomegaly, lymphadenopathy) and disproportionate joint pain.
• Significant laboratory differences included anemia, leukopenia, and neutropenia in LA, while platelet counts were lower-normal in LA versus JIA. The logistic regression model achieved 100% classification accuracy.

Conclusions:

• Acute lymphoblastic leukemia (ALL) must be considered in children presenting with arthritis and hematological abnormalities, particularly leukopenia and neutropenia.
• Key indicators for LA include severe joint pain unresponsive to analgesics, nocturnal pain, fever, lymphadenopathy, and hepatosplenomegaly.
• Established criteria can effectively differentiate between leukemic arthritis and juvenile idiopathic arthritis, enabling timely diagnosis and intervention.