From Steroid-Dependent IgA Vasculitis to Colchicine-Resistant Familial Mediterranean Fever in a Child with Homozygous M694I Mutation: A Case Report from the Algerian Cohort

Background Familial Mediterranean fever (FMF) is an autoinflammatory disease caused by MEFV mutations. IgA vasculitis (Henoch-Schönlein purpura) and IgA nephropathy may be presenting manifestations, particularly in patients with severe genotypes. In a cohort of 58 Algerian patients with FMF and renal involvement, we identified two cases of IgA nephropathy, including this paediatric case. Case presentation A boy of Mediterranean origin (born 30 August 2007) first presented at age 9 years (April 2017) with fever, purpura of the lower limbs, arthralgia, abdominal pain, rectorrhagia and macroscopic haematuria. He was diagnosed with IgA vasculitis and treated with long-term corticosteroids. He remained corticosteroid-dependent with recurrent cyclic abdominal pain. At age 12 years, he was hospitalised in February 2020 for a flare characterised by sock-distribution purpura, a pseudo-erysipelas lesion on the right foot triggered by football, fever, arthralgia, arthritis, cervical lymphadenopathy, unilateral orchitis, pleural effusion, peritoneal effusion and hepatosplenomegaly. Laboratory tests showed hyperleucocytosis (22 000/mm 3 with neutrophilia), mild normocytic anaemia (11.8 g/dL), CRP 126 mg/L, normal renal function, and 24-hour proteinuria at 470 mg. Urinalysis showed haematuria with casts. Kidney biopsy revealed global and diffuse mesangial IgA deposits (+++, "dead tree" pattern) without crescents or amyloid, consistent with IgA vasculitis grade IIIa (ISKDC) / grade IV (Meadow). MEFV genetic testing (performed in 2020 by the private laboratory CERBA, interpreted in France) showed homozygosity for p.Met694I (M694I). Corticosteroids were tapered and colchicine introduced (1 mg/day, then increased to 2 mg/day at age 15, and to 3 mg/day at age 16). The patient remained symptom-free for about 3 years. At age 18 years (202), a stress-induced flare (school examination) occurred despite colchicine 3 mg/day. Secondary colchicine resistance was diagnosed, and anakinra 100 mg/day subcutaneously was added, with rapid clinical and biological improvement. Skin biopsy of the purpura confirmed leucocytoclastic vasculitis with IgA deposits; biopsy of the pseudo-erysipelas lesion showed non-specific dermal inflammation without vasculitis. Conclusion Recurrent or corticosteroid-dependent IgA vasculitis in a child from a Mediterranean population should prompt early MEFV genetic testing. Pseudo-erysipelas lesions, serositis, hepatosplenomegaly and very high CRP are important clues. Colchicine resistance may develop; anakinra is a safe and effective second-line option.