Juvenile xanthogranuloma. Clinicopathologic analysis and immunohistochemical study of 57 patients.

Fifty-seven cases of juvenile xanthogranuloma that fulfilled the classic description of histologic findings of the disease were analyzed clinicopathologically and immunohistochemically. Two forms could be distinguished: 47 cases of the infantile form and 10 of the adolescent and young adult form. The infantile lesion was found at birth in 8 patients (17%), and was noted within 1 year after birth in 33 (70%). Twenty-two had multiple lesions and five of the six for whom follow-up was feasible had spontaneous involution. About half of the lesions were located on the head and neck, 30% on the trunk, and 20% on the extremities. All six adolescents had a solitary tumor located in the head and neck region. Comparison of the latter form with reticulohistiocytoma and cutaneous fibrous histiocytoma was established from a differential point of view. Immunohistochemically, most lesions of juvenile xanthogranuloma displayed a positive reaction for lysozyme and alpha-1-antichymotrypsin and were negative for S-100 protein, thereby suggesting that the essential constituents of this lesion would derive from the mononuclear phagocyte system.