[Osteoma of the mastoid: apropos of 2 cases].

The authors report two cases of mastoid osteoma: it is a rare benign tumor attached to the cortex of the mastoid bone, approximatively fifty cases have been described in the english language literature and eight in the french literature. The clinical and radiological characteristics combined with histopathologic evidence demonstrate the diagnosis of mastoid osteoma, the most common type being the compact osteoma. Differential diagnosis should be considered with others benign bone-forming lesions (osteochondroma, chondroma, osteoblastoma, exostosis, fibrous dysplasia...) and with malignant lesions (osteosarcoma...). Surgical removal proposed for cosmetic deformity is a simple procedure for the vast majority of small osteomas. Early surgical intervention is recommended to avoid the evolution toward giant osteoma with potential risks of surgical complications.