Quantitative analysis of the plain radiographic appearance of Brodie's abscess.

RATIONALE AND OBJECTIVES: The authors quantitate the radiographic features that distinguish the plain radiographic appearance of Brodie's abscess (BA) from other solitary lesions of bone.

METHODS: Plain radiographs of 709 solitary bone lesions were reviewed, including 21 BAs. These were analyzed according to demographic, gross anatomic, and structural features. Vector analysis of groups of features was performed to determine those that are most sensitive and specific for the radiographic appearance of BA relative to other lesions of bone.

RESULTS: Brodie's abscesses, in our series, are most commonly medullary-based (86%) lytic lesions (100%), with a geographic pattern of destruction (100%), well-defined edges (90%), marginal sclerosis (86%), and no bone enlargement (95%). In general, they have no periosteal reaction (71%), cortical break (95%), or visible matrix (90%). They typically are localized to the diaphysis or metaphysis (86%) of tubular bones, particularly in the lower extremity (63%). By vector analysis, the radiographic and demographic description of BA that provided the greatest sensitivity (67%-76%) while maintaining high prevalence (20%-21%) included a well-defined lytic lesion with a geographic pattern of destruction, and no bone enlargement or matrix or cortical break arising in patients younger than 40 years old. Although BAs commonly are small lesions with maximum diameters < 50 mm, size criteria did not greatly affect the sensitivity or specificity for detection of BA in our database. The differential diagnosis generated by vector analysis includes osteoid osteoma, nonossifying fibroma, giant cell tumor, eosinophilic granuloma chondroblastoma, and fibrous dysplasia, as the major lesions.

CONCLUSIONS: Although BA can present with a variety of radiographic features, a relatively specific set of radiographic characteristics can be defined to assist in plain-film diagnosis and to help refine the differential diagnosis of similar-appearing lesions.