Abstract: Cutaneous actinomycosis manifesting as pustules and pus lakes on both lower extremities is rare at home and abroad. We herein report one such case. A 27-year-old male had a 10-year history of membranous nephropathy. He presented with induration, ulceration, yellow pus discharge and pain in both lower extremities for 2 years. The rash subsequently spread to the trunk and upper limbs, accompanied by intermittent fever and severe pain for 3 months. Multiple treatments showed unsatisfactory efficacy, and the condition deteriorated. Pus and tissue cultures were positive for Staphylococcus and Actinomyces. Metagenomic next-generation sequencing (mNGS) confirmed Actinomyces. Due to the patient's allergy to penicillin and moxifloxacin, oral doxycycline combined with rifampicin was administered. Skin lesions improved significantly after 17 days of treatment.

Key words: membranous nephropathy, cutaneous actinomycosis