Abstract: Wang Guangping, Wang Xiaopo, Chen Hao, Zhang Wei, Jiang Yiqun, Zeng Xuesi, Xu Xiulian, Sun Jianfang Department of Pathology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China Corresponding author: Sun Jianfang, Email: fangmin5758@aliyun.com 【Abstract】 Objective To investigate clinicopathological features of granulomatous slack skin （GSS）. Methods Clinical and pathological data were obtained from 6 cases of GSS, and analyzed retrospectively. Results All the 6 patients were males, and presented with slack plaques and even pendulous skin folds. These skin lesions mainly affected flexural areas in 5 patients, and only occurred in the right chest in 1 patient. One patient was diagnosed with GSS complicated by mycosis fungoides （MF）. Histopathological examination showed non-caseating granulomas with infiltration of medium-sized lymphoid cells and multinucleated giant cells in the dermis in all the patients, atypical lymphoid cells in 1 patient, and epidermotropism in another patient. Immunohistochemical study revealed monoclonal CD4+ lympho-cytosis. Elastic fiber staining was performed in 4 patients, and showed crimp, fracture and disappearance of elastic fibers, and elastic fiber phagocytized by multinuclear giant cells in 2 patients. There were monoclonal rearrangements of T-cell receptor （TCR） γ gene in 2 patients. After radiotherapy with electron beam or superficial X-ray, lesions of 2 patients became smaller, and then were excised completely without recurrence. The other 4 patients received intramuscular injection of interferon α-2b and topical application of 0.02% mechlore-thamine solution, and their condition was improved. Conclusions GSS has a slowly progressive course, and overtreatment is not recommended. Surgical excision may be the first choice for GSS localized in flexural areas.