Osteoid osteoma (ICD: 9191/0) and osteoblastoma (ICD: 9200/0) are clos
ely related entities of osteoblastic-type tumors. Osteoid osteoma is a
small benign (lesion 1-2 cm or less) neoplasm that is richly vascular
ized. Nerve fibers within the tissue surrounding the nidus lead to the
characteristic pain. A typical finding is the perifocal osseous react
ion around the nidus. Osteoblastoma is a progressively growing lesion
of a diameter larger than 2 cm; it is sometimes painful and is charact
erized by the absence of any reactive perifocal bone formation. For bo
th tumors the treatment is complete surgical excision. If the nidus of
the osteoid osteoma is removed, the patient will be free of pain. For
the osteoblastoma the treatment depends on the stage and localization
of the tumor. Forty-seven patients with osteoid osteoma and 10 patien
ts with osteoblastoma have been treated in Heidelberg since 1980. The
radiological investigations and surgical treatment are discussed.