Abstract: Sun Juan, Xu Jiaosheng, Wei Li, Han Xiaofeng Department of Dermatology, Beijing Children′s Hospital, Capital Medical University, National Center for Children′s Health, Beijing 100045, China Corresponding author: Han Xiaofeng, Email: peak_h@aliyun.com 【Abstract】 Objective To analyze the clinical and pathological features of childhood bullous pilomatricoma. Methods The clinical and pathological features were analyzed in 16 patients with bullous pilomatricoma, who visited Department of Dermatology of Beijing Children′s Hospital from 2013 to 2017. Results Among the 16 patients, 5 were males, and 11 were females. Their age of onset ranged from 4 months to 11 years, and the median age of onset was 8.5 years. Their course of disease ranged from 2 months to 4 years, and the average course of disease was 10 months. The tumors were found predominantly on the upper limbs （10 cases, including 7 on the upper arm, 2 on the shoulder and 1 on the forearm）, followed by the face （4 cases） and the neck （2 cases）. These tumors manifested as limited pushable red lumps with blister-like appearance, and telangiectasia was observed on the surface of some lesions. The diameters of the lumps ranged from 0.5 cm to 3 cm, and hard nodules could be detected in the blisters by palpation. Under dermoscopy, uniform red background was observed in 16 cases, unstructured white area in 13, unstructured blue-grey area in 4, and liner or irregular branched vessels. Two or more dermoscopic features were observed in 15 patients. All the skin lesions were resected by surgery, and no recurrence was observed during the follow-up of 1 - 5 years. Histopathological examination showed that the tumors were located in the middle to deep dermis, and mainly consisted of basaloid cells and shadow cells, as well as transitional cells between the above two kinds of cells. Varying degrees of infiltration of inflammatory cells and hyperplasia and calcification of the fibrous connective tissue were observed in the tumor interstitium, with multinucleated giant cells in some areas. There were varying degrees of infiltration of inflammatory cells, lymphangiectasis, reduction or absence of elastic fibers in the dermis between the epidermis and tumors. Conclusions Childhood bullous pilomatricoma mostly occurs on the upper limbs, face and neck. Histopathologically, the tumor consists of basaloid cells and shadow cells with lymphangiectasis and reduction of elastic fibers in the dermis. The main dermoscopic features are red background and unstructured white areas. Its prognosis is good after surgical excision.

Key words: Pilomatrixoma, Child, Dermoscopy, Skin manifestations, Pathologic processes, Bullous pilomatricoma