Abstract
1. Forty patients with solitary eosinophilic granuloma of bone from the Hospital for Sick Children, Toronto, have been reviewed. They had clinical and laboratory findings similar to those reported by others except for the erythrocyte sedimentation rate, which was raised in nearly half the patients tested.
2. Radiographs in all cases showed the lesion to be osteolytic. In the skull and cervical spine there was no bony reaction ; in the thoracic and lumbar spine the typical picture of Calvés disease was produced; in long bones the cortex commonly showed endosteal erosion and periosteal reaction.
3. In one patient the lesion progressed so rapidly that the body of a cervical vertebra was destroyed within ten days.
4. The differential diagnosis includes sarcoma. Biopsy is essential.
5. All the patients improved regardless of the treatment they received. Complications were due either to the site of the lesion or to its treatment.
6. Expansion of the lesion after biopsy indicates a more widespread manifestation of histiocytosis X.
