Histiocytosis X: rate and pattern of resolution of osseous lesions.

Resolution rate and qualitative characteristics of healing were studied in 71 osseous lesions of histiocytosis X. Rates of healing, as assessed planimetrically and by vertebral body-height measurement, did not differ significantly among lesions that were treated with chemotherapy alone, chemotherapy plus radiation, radiation alone, or those that received no treatment. Lesions of Letterer-Siwe disease, Hand-Schuller-Christian disease, multiple eosinophilic granuloma, and solitary eosinophilic granuloma resolved at comparable rates. A trend toward more rapid healing was noted in younger children. Lesions treated with radiation alone showed a greater tendency to resolve with sclerosis, but radiographic healing characteristics did not strictly depend upon specific mode of therapy. These results support the concept of osseous histiocytosis X as a benign self-limited disorder when systemic disease is absent, and they encourage therapeutic conservatism.