Mixed Connective Tissue Disease in a Girl with Lower Extremities Edema: A Brief Report

Mixed Connective Tissue Disease (MCTD) in children is rare and often presents with overlapping features of multiple rheumatologic disorders. This report discusses an 8-year-old girl with symptoms including fever, hair loss, lower extremities edema, weakness, and oral ulcers, who was diagnosed with MCTD due to a high titer of anti-U1 RNP antibodies. Treatment with immunomodulator drugs led to disease remission. The case highlights the diagnostic challenges of MCTD in pediatric patients and suggests that serum anti-U1 RNP testing can be a valuable diagnostic tool, especially in cases with recurrent muscular weakness, lupus-like symptoms, and edema.