BACKGROUND: Osteoma of the skull and facial bones is not uncommon, is usually asymptomatic, and may be associated with Gardner's syndrome. Osteomas involving other bones are unusual. METHODS: The authors describe 14 cases (eight men and six women from age 21-66 years) of parosteal osteoma of bones other than of the skull and face. RESULTS: Thirteen lesions involved long bones, and one involved the clavicle. A long-standing (18 months to 31 years) mass was reported in seven patients. Symptoms of pain, a mass, or both were present in all except three patients who were asymptomatic. Lesions ranged from 2.5 to 20 cm in greatest dimension. Histologically, they blended with the cortex, did not infiltrate the medullary cavity, and consisted of dense sclerotic lamellar bone with haversian systems, similar to the architecture of normal cortical bone. There was no spindle cell proliferation. Nine patients underwent resection, four had biopsy, and one had debulking. With a follow-up of 1-23 years, no recurrence or metastasis was reported. CONCLUSIONS: Parosteal osteoma must be distinguished from parosteal osteosarcoma, a low grade malignant neoplasm. If radiographs do not identify areas of radiolucency and sections do not contain spindle cells, the diagnosis of parosteal osteoma is justified.
BACKGROUND:Osteoma of the skull and facial bones is not uncommon, is usually asymptomatic, and may be associated with Gardner's syndrome. Osteomas involving other bones are unusual. METHODS: The authors describe 14 cases (eight men and six women from age 21-66 years) of parosteal osteoma of bones other than of the skull and face. RESULTS: Thirteen lesions involved long bones, and one involved the clavicle. A long-standing (18 months to 31 years) mass was reported in seven patients. Symptoms of pain, a mass, or both were present in all except three patients who were asymptomatic. Lesions ranged from 2.5 to 20 cm in greatest dimension. Histologically, they blended with the cortex, did not infiltrate the medullary cavity, and consisted of dense sclerotic lamellar bone with haversian systems, similar to the architecture of normal cortical bone. There was no spindle cell proliferation. Nine patients underwent resection, four had biopsy, and one had debulking. With a follow-up of 1-23 years, no recurrence or metastasis was reported. CONCLUSIONS:Parosteal osteoma must be distinguished from parosteal osteosarcoma, a low grade malignant neoplasm. If radiographs do not identify areas of radiolucency and sections do not contain spindle cells, the diagnosis of parosteal osteoma is justified.