Juvenile hyalin fibromatosis.

A boy had multiple large tumors on the scalp, whitish nodules on the nape and both sides of the neck, hypertrophic gingiva, and severe flexural contractures of hip and knee joints. The histopathologic structure of the tumor was characteristic of juvenile hyalin fibromatosis. The tumor cells were embedded in an amorphous eosinophillic ground substance. X-ray films revealed numerous osteolytic and osteociastic lesions that are important findings in the study of this disease.