NERDS: A Syndrome with Two Faces

NERDS syndrome (Nodules, Eosinophilia, Rheumatism, Dermatitis, Swelling) is a rare eosinophilic inflammatory disorder, characterized by the presence of periarticular or subcutaneous nodules, persistent peripheral eosinophilia, arthralgias resembling rheumatoid arthritis, chronic dermatitis, and limb swelling. To provide a comprehensive overview of the clinical, laboratory, and histopathological features of NERDS syndrome, and to propose a structured diagnostic approach to differentiate it from other eosinophilic or rheumatologic conditions. We conducted a systematic review of published cases of NERDS syndrome, analyzing clinical manifestations, laboratory findings, histopathological features, and response to treatment. We propose a structured diagnostic approach to differentiate it from other eosinophilic or rheumatologic conditions. NERDS syndrome typically presents with firm nodules near joints, rheumatoid-like joint pain, dermatitis, and localized or generalized swelling. Laboratory tests show marked eosinophilia (>1500/μL), elevated inflammatory markers (CRP, ESR), and eosinophilic infiltration in affected tissues. The main differential diagnoses include DRESS syndrome, eosinophilic granulomatosis with polyangiitis, idiopathic hypereosinophilic syndrome, eosinophilic rheumatoid arthritis, and parasitic infections. NERDS syndrome is a distinct eosinophilic disease requiring careful clinical and laboratory evaluation to ensure accurate diagnosis. Systemic corticosteroids remain the first-line therapy and usually result in rapid improvement. In refractory or relapsing cases, immunosuppressive or biologic agents may be considered. The proposed diagnostic approach may facilitate early recognition and optimal management of this underdiagnosed condition.