Fibro-osseous lesions of the external auditory canal

Objectives: To differentiate a novel type of benign circumscribed bone lesi on of the external auditory canal hom those described previously, such as e xostoses and osteomas, Study Design: Information was obtained from computed tomography (CT) images, surgical findings, and pathologic study. Methods: Five patients (26 to 82 years old) who presented a hard, round, unilateral, skin-covered mass occluding the external auditory canal to varying degrees were studied. A CT study carried out before resection of the lesions by cu rettage disclosed the absence of a bony connection to the underlying struct ures. All the tissue specimens underwent pathologic study. Results: CT and surgical findings demonstrated the absence of a connective pedicle, The pat hologic findings showed lesions consisting of an osteoma-like bone formatio n with sparse osteoblastic areas; mature lamellar bone was observed in thre e cases, bone marrow containing adipose tissue and hematopoietic remnants i n two, and a dense, collagenous stroma in another. They all showed irregula r trabeculae, bordered by osteoid osteoblasts, In no case was there evidenc e of a relationship to the cartilaginous tissue or to the bony structures o f the external auditory canal. Conclusions: The data obtained from the clin ical, CT, surgical, and pathologic findings suggest the existence of a lesi on unlike those previously known, possibly related to ossifying reactions i n other parts of the organism.