Urticaria pigmentosa (UP) is characterized by dense aggregates of mast cells in the dermis. There is consistent evidence from the literature that mast cells may play a pathogenetic role in the development of neurofibromas and other tumors. Objective: To study the concomitant appearance of UP with neurofibromas and neurofibroma-like neoplasms. Methods: We analyzed 31,752 records of patients examined at the Department of Dermatology in the year 2000, looking for UP and associated neurofibromas

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... neurofibroma-like neoplasms in persons younger than 18 years. Results: We identified a total of 27 patients suffering from UP, with 16 persons younger than 18 years. One 12-year-old Caucasian boy demonstrated multiple cutaneous mastocytomas consistent with the diagnosis of UP. On his trunk, four café-au-lait spots were found. A cutaneous neurofibroma was confirmed by skin biopsy. Magnetic resonance imaging detected multiple neoplasms located at the nerve roots of the spine, resembling plexiform neurofibromas. Conclusions: There may be a concomitant appearance of UP and neoplasms, with mast cells possibly playing a causative role. The existence of neoplasms, including neurofibromas and neurofibroma-like lesions should be considered when examining UP cases.