Abstract: 【Abstract】 Objective To investigate clinical manifestations, pathological features and outcomes of primary osteoma cutis in children. Methods Eleven children with confirmed primary osteoma cutis diagnosed in Department of Dermatology, Beijing Children′s Hospital between 2011 and 2018 were included into this study. The clinical manifestations, histopathological features, and outcomes were analyzed retrospectively. Results Among the 11 patients, 7 were males and 4 were females. Primary osteoma cutis occurred within 22 months after birth in all the children, the median age of onset was 1 month, and the disease occurred during the first 6 months of life in 10 children. The skin lesions were characterized by skin-colored or reddish indurated papules, plaques or nodules of varying size with slight epidermal atrophy. Three patients had local skin lesions, and 8 had multiple skin lesions. Serum calcium and parathyroid hormone levels were within normal limits in all the children, and no developmental deformity was observed at birth in any of the children. Histopathological examination revealed the formation of mature lamellar bone in the dermis in all the cases, which involved the subcutaneous adipose tissue in 5 cases. The skin lesions became stable 8 - 18 months after the occurrence in 10 patients, which was consistent with primary plaque-like osteoma cutis. Only 1 patient underwent a slowly progressive course, and the skin lesions involved subcutaneous deep tissues, leading to dyskinesia, which was consistent with progressive osseous heteroplasia. Conclusions Primary osteoma cutis in children mostly occurs in infancy, whose clinical manifestations are atrophic, indurated plaques or nodules, and its main pathological feature is the formation of mature lamellar bone. Long-term follow-up is needed, and attention should be paid to the occurrence of progressive osseous heteroplasia.

Key words: Ossification, heterotopic, Child, Osteoma cutis, Primary