Cicatricial Alopecia of the Scalp as a Manifestation of IgG4-Related Disease Mimicking Acne Keloidalis Nuchae

This case study discusses a 23-year-old Japanese man with scalp IgG4-related disease (IgG4-RD) that resembled acne keloidalis nuchae (AKN). The patient had a non-painful alopecic plaque on the occipital scalp, with dense dermal fibrosis and numerous IgG4-positive plasma cells, but lacked the perifollicular inflammation typical of AKN. Elevated serum IgG4 levels confirmed IgG4-RD. Treatment with intralesional triamcinolone led to mild improvement, though alopecia remained. The study emphasizes the need to consider IgG4-RD in atypical cicatricial alopecia diagnoses and the role of IgG4 immunostaining in differentiating it from other scarring conditions.