Juvenile xanthogranuloma occurring in the oral cavity: case report and histopathological findings.

Juvenile xanthogranuloma is commonly seen in the dermis, and only very rarely develops in the oral mucosa. Here were report a case that occurred in the anterior palate of a 9-year-old boy. The lesion appeared as a dark red and well-defined nodule measuring 12 x 14 mm. Histologically, it consisted of a proliferation of histiocytes and fibroblastic stroma intermingled with foamy cells. Many lipid droplets without limiting membrane were observed in the cytoplasm under electron microscopy, but no Langerhans' cell granules were observed. The proliferative histiocytes were positive for lysozyme and macrophage HAM56 under immunohistochemical observation, but not for S-100 protein. From these findings, the lesion was diagnosed as juvenile xanthogranuloma. The post-operative course, now amounting to 7 years, has been uneventful.