[Juvenile Sharp syndrome (mixed connective tissue disease)].

Area of Science:

• Pediatric Rheumatology
• Autoimmune Diseases
• Clinical Immunology

Context:

• Sharp syndrome, also known as Mixed Connective Tissue Disease (MCTD), is an autoimmune disorder.
• Pediatric cases of Sharp syndrome are less common and may present differently than in adults.
• Understanding the specific clinical and laboratory features in children is crucial for diagnosis and management.

Purpose:

• To describe the clinical and laboratory characteristics of Sharp syndrome in a cohort of five children.
• To identify key diagnostic markers, including autoantibodies, in pediatric Sharp syndrome.
• To evaluate the initial prognosis for children diagnosed with Sharp syndrome.

Summary:

• Five children with Sharp syndrome exhibited non-erosive polyarthritis, hand/finger swelling, Raynaud phenomenon, and rashes resembling dermatomyositis or SLE.
• Key laboratory findings included elevated ESR, anemia, leukopenia, high-titer IgM rheumatoid factor, and antinuclear antibodies (ANA) with a speckled pattern.
• All patients possessed antibodies against extractable nuclear antigens (Anti-ENA), specifically anti-ribonucleoproteins (Anti-RNP), which are IgG-based and bind complement.

Impact:

• This study highlights the characteristic presentation of Sharp syndrome in children, aiding in earlier and more accurate diagnosis.
• Identification of specific autoantibodies (Anti-ENA, Anti-RNP) serves as important diagnostic biomarkers in pediatric autoimmune diseases.
• The findings suggest a generally favorable prognosis for children with Sharp syndrome, with limited renal or cerebral involvement observed.