Fasciitis-panniculitis syndrome with autoantibodies reacting to collagen fibers: A case report

Abstract Background : Fasciitis-panniculitis syndrome (FPS) typically presents with swelling and skin hardening. Its histopathological characteristics include inflammatory cell infiltration and fibrous thickening of the subcutaneous tissue and fascia. No case describing FPS in children had been reported. We encountered a case of a 10-year-old boy in which prednisolone and famotidine were effective in managing the relapsed FPS. Case presentation : The patient developed a high fever and skin swelling with pain and erythema on the right side of his body following an abrasion injury on his right wrist at the age of 5 years, and was suspected of having streptococcal toxic shock-like syndrome, for which he received antimicrobials, immunoglobulin therapy, debridement, and plasma exchange. The same presentation with similar magnetic resonance imaging (MRI) findings of inflammatory spillover in the fat tissue and fascia was observed twice at the age of 6 years. Serological analyses for conventional autoantibodies, bone marrow aspiration and whole-exome sequencing examination were non-remarkable. Prednisolone was effective in ameliorating the above putative autoinflammatory syndrome. The patient was admitted at the age of 10 years with similar clinical and MRI findings indicative of recurrence of the same disease. En bloc biopsy from the skin to the fascia showed thickening of collagen fibers, infiltration of inflammatory cells composed mainly of neutrophils and lymphocytes, and necrotizing vasculitis in the fat tissue and fascia. Immunohistochemical staining of the en bloc biopsy sections indicated infiltration of T lymphocytes and macrophages in the perivascular connective tissue and fibrinoid necrosis, supporting the diagnosis of FPS. Induction therapy with prednisolone resulted in a remission. IgG purified from the patient’s serum reacted with collagen fibers in the lipofibrous septa. The patient is currently taking famotidine to prevent relapses and is making good progress in his recovery. Conclusions: Although pathogenic autoantibodies have not been described in FPS, our results suggest that collagen-reactive autoantibodies may be involved in the pathogenesis of FPS.