Abstract: Jin Xianhua, Yu Kai, Chang Li, Wang Yiyu, Mou Yan, Li Xue, Zhu Wenjing, Xia Jianxin. Department of Dermatology, Second Hospital, Jilin University, Changchun 130041, China Corresponding author: Xia Jianxin, Email: jianxinxia2003@tom.com 【Abstract】 Objective To analyze the clinicopathological features of acute monocytic leukemia cutis. Methods A retrospective study was performed on four patients with acute monocytic leukemia with skin lesions as the initial presentation. Results All the patients were elderly people with the age being 68, 70, 74 and 82 years respectively. Typical cutaneous lesions were multiple, reddish or purple, tenacious papules, plaques, or nodules involving the trunk and extremities. There was no obvious subjective symptom. Histopathologically, there was a dense and diffuse infiltration of numerous monomorphous tumor cells in the dermis, which were medium-sized, kidney- or oval-shaped with obvious atypia and arranged concentrically around blood vessels or appendages or linearly between collagen fibers. An uninvolved zone of papillary dermis that separated the normal epidermis from the underlying dermal infiltrate was observed. Immunohistochemical analysis showed that the tumor cells were positive for CD68, CD4, CD45RO, CD56, leukocyte common antigen （LCA）, but negative for CD3, CD20, CD30, CD34, CD117 and CD123. Conclusions Acute monocytic leukemia cutis mainly occurs in elderly people, which is pathologically characterized by a dense monomorphous infiltration of tumor cells between collagen fibers throughout the dermis as well as an uninvolved zone between the dermis and epidermis.

Key words: Leukemia, myelomonocytic, acute, Pathological processes, Skin manifestations