Three cases of pigmented cosmetic dermatitis‐like eruptions associated with primary Sjögren's syndrome or anti‐<scp>SSA</scp> antibody

Pigmented cosmetic dermatitis-like (Riehl's melanosis-like) pigmentation was reported in three of 27 patients with primary Sjögren's syndrome. But case reports of such eruptions are rare. We describe three cases of such eruptions associated with primary Sjögren's syndrome or anti-SSA antibody and possible associations with specific types of human leukocyte antigen (HLA) and infiltrating lymphocytes. These middle-aged Japanese women had reticular facial pigmentation and histopathological examination revealed interface dermatitis, melanophages, and dense lymphocytic infiltration around hair follicles and sweat ducts. HLA typing revealed common antigenic equivalents or genetic typing of HLA-A2, DR52, DPA1(02:02) and DPB1(05:01). Immunohistochemical staining revealed major subsets of T cells to be CD8 and CD45RO. Some Foxp3- and few IL17-positive cells were found in strong contrast to the major CD4 subset of infiltrated T cells in annular erythema associated with Sjögren's syndrome. Apparently, our patients' pigmentation represented a specific etiology associated with primary Sjögren's syndrome or anti-SSA antibody.