Abstract： A long-term misdiagnosed case of granulomatous slack skin complicated by chronic cutaneous ulcer is reported.A 40-year-old male patient presented with a 5-year-history subcutaneous mass and painful ulcers on the left buttock,as well as 1-year-history slack skin on skin folds.Dermatological examination showed diffuse dark erythematous plaques on the left buttock,with irregularly sized deep ulcers on their surface.Slack skin was obvious on skin folds.Histopathological examination revealed mononuclear cells migrating into the epidermis,diffuse dermal infiltration of lymphocytes and histocytes with the presence of muhinuclear giant cells.Immunohistochemistry demonstrated that these lymphocytes were positive for CD3,CD43,CD45RO,but negative for CD20 or CD79α,and multinuclear giant cells were positive for CD68.