Abstract: 【Abstract】 Objective To analyze clinical manifestations, histopathological and pathogenic fungus characteristics as well as treatment of 3 cases of disseminated cutaneous alternariosis caused by Alternaria. Methods Clinical data were collected from 3 cases of disseminated cutaneous alternariosis caused by Alternaria, who were diagnosed in Department of Dermatology, Xijing Hospital from 2019 to 2021, and clinical and histopathological features, fungal culture, strain identification and treatment results were retrospectively analyzed. Results The 3 patients were aged 55, 41 and 46 years respectively, including 1 male and 2 females. Two patients were previously diagnosed with nephrotic syndrome and 1 with systemic lupus erythematosus. All the patients had a history of taking glucocorticoids and tacrolimus for different durations, and experienced chronic infections. Histopathological examination with hematoxylin and eosin （HE） staining showed double-contour thick-walled spores and knot-shaped thick-walled septal hyphae, but no melanin in skin lesions. Sequencing of the fungal internal transcribed spacer region confirmed that 2 cases were infected with Alternaria alternate, and 1 with Alternaria infectoria. Fungal culture at different temperatures showed that the growth ability of Alternaria markedly decreased at the temperature over 35 ℃. To treat these patients, the dose of tacrolimus was reduced to less than 1/3 of the standard dose, or tacrolimus was switched to other immunosuppressants, and systemic antifungal therapy was also given at the same time. After 7-month treatment, good clinical outcomes were achieved in the 3 patients. Conclusion Disseminated cutaneous alternariosis is characterized by bilateral hematogenous dissemination and lymphatic distribution in unilateral limbs, and the skin lesions are characterized by verrucous plaques covered with scabs, nodules and/or sinuses.

Key words: Alternariosis, Skin manifestations, Disseminated cutaneous alternariosis, Alternaria, Chlamydospore