Of seven patients seen in the University of Iowa Hospitals, each having an osteoid osteoma, One represents the first published report of this condition in a rib. The ages of the patients varied from fourteen months to twelve years. The main clinical symptom was localized pain of from several months' to one year's duration.

Peculiar deformities, produced by the presence of the osteoid osteoma, were noted in three patients. The patient with an osteoid osteoma in a rib had a total C curve of the spine, which improved and finally disappeared after the removal of the lesion. A fourteen-month-old child had a varus deformity of the ankle, produced by an osteoid osteoma in the lower end of the diaphysis of the fibula. The osteoid osteoma in this patient had evidently stimulated the growth of the lower epiphyseal plate of the fibula. An inward bowing of the tibia developed in the third patient, due to an osteoid osteoma in the inner aspect of the upper portion of the tibia.

Mainly because of the typical histological appearance of the lesion, the authors believe, with Jaffe, that the osteoid osteoma is a benign neoplastic formation.

Three patients (Cases 1, 6, and 7) were cured by block resection of the osteoid osteoma and surrounding area. In three patients treated by curettage of the involved area, the lesion recurred (Cases 2, 3, and 4) and had to be resected in a second operation. The osteoid osteoma in the phalanx of one patient was excochleated twice and recurred. The roentgenograms of this lesion have not shown essential changes in over four years.

The authors' experience indicates that the treatment of the osteoid osteoma must consist of an extensive block resection of the lesion, together with removal of a good deal of the surrounding sclerotic bone.