Case Report: Ivarmacitinib in the treatment of refractory primary cutaneous amyloidosis.

Primary cutaneous amyloidosis (PCA) is a chronic, severely pruritic dermatosis characterized by amyloid deposition in the dermis. There is currently no standardized treatment for PCA, and its clinical management remains challenging. Ivarmacitinib, a novel, highly selective oral Janus kinase 1 (JAK1) inhibitor, has demonstrated significant efficacy in modulating inflammatory and pruritic pathways in atopic dermatitis (AD), suggesting its potential utility in related conditions. We report a compelling case of a 65-year-old male with a 15-year history of severe, refractory PCA who had failed multiple conventional treatments, including topical corticosteroids, systemic retinoids, and immunomodulators, owing to either poor tolerability or insufficient efficacy. Thus, ivarmacitinib was initiated as a targeted therapeutic intervention, and it resulted in rapid improvement: pruritus subsided within 24 h and resolved completely within one week, followed by significant flattening and fading of hyperpigmented papules over the ensuing weeks, with no adverse events observed during follow-up. This case suggests that ivarmacitinib may be a promising, effective, and well-tolerated therapeutic option for refractory PCA, likely through targeting the JAK/STAT pathway central to disease pathogenesis.