Histiocytosis-X: role of histology and S-100 protein in grading the severity of disease.

Histiocytosis-X encompasses a wide clinical spectrum from a benign localised lesion to acute generalised disease with malignant behaviour. We have reviewed material from our 18 retrospective cases comparing histological features with clinical data. Degree of positivity for S-100 protein was studied by immunoperoxidase method. Our results indicate that diagnosis of histiocytosis-X necessitates histological confirmation but grading of histological criteria and S-100 positivity do not allow prediction of severity and extent of the disease.