Abstract: 【Abstract】 Objective To investigate clinical and histopathological features of mucinous nevi. Methods Clinical and pathological data were collected from 10 patients with clinically and histopathologically confirmed mucinous nevi in Hospital of Dermatology, Chinese Academy of Medical Sciences from January 2014 to December 2019, and retrospectively analyzed. Results All cases developed mucinous nevi in childhood, with an average age of onset being 6.5 years. Of the 10 patients, 7 had lesions on the trunk, among whom 4 had lesions on the back; the remaining 2 had lesions on the limbs, and 1 had generalized lesions on the trunk and limbs. The skin lesions were locally arranged in lines, bands or clusters, and skin-colored, reddish or yellow in color，with the texture varying from soft to hard. Histopathological examination showed that 10 patients presented with disordered arrangement of collagen fiber bundles in the dermis and mucin deposition at varying locations and to different degrees among them, 6 with thickened and red-stained collagen fibers in the deposition area, and the remaining 4 with sparse and decreased collagen; focal liquefaction degeneration of the basal layer was observed in 2 cases, and different amounts of mature adipose tissue in the dermis were seen in 3 cases. Conclusions Mucinous nevus pathologically manifests as mucin deposition of varying degrees among disorderedly arrangd collagen fiber bundles in the dermis, which is similar to some other diseases, and is easily misdiagnosed. Close combination of clinical and pathological features facilitates confirmed diagnosis.

Key words: Neoplasms, connective tissue, Pathologic processes, Skin manifestations, Diagnosis, Mucinous nevus, Mucin deposition