Concomitant Systemic Autoinflammatory Diseases: Diagnostic and therapeutic challenges

Area of Science:

• Genetics
• Immunology
• Pediatrics

Background:

• Systemic autoinflammatory diseases (SAIDs) encompass a range of genetic disorders.
• Neonatal-onset multisystem inflammatory disease (NOMID) and familial Mediterranean fever (FMF) are distinct SAIDs.
• Accurate diagnosis and management of coexisting SAIDs are crucial.

Observation:

• A 3-month-old infant presented with recurrent fever, urticarial rash, and polyarthritis.
• Initial investigations suggested NOMID, but treatment optimization with anakinra was insufficient.
• Genetic testing revealed heterozygous MEFV mutations and later NLRP3 somatic mosaicism.

Findings:

• The patient was diagnosed with coexisting NOMID and FMF.
• NLRP3 somatic mosaicism confirmed the NOMID diagnosis.
• Adding colchicine to anakinra stabilized disease activity.

Implications:

• Somatic mosaicism should be considered in NOMID cases negative for germline mutations.
• Combined treatment strategies are necessary for managing coexisting SAIDs.
• This case highlights diagnostic and therapeutic challenges in complex pediatric autoinflammatory conditions.