Milk cloud appearance—a characteristic sign of fibrous dysplasia on contrast-enhanced MR imaging

Comparison of MRI Findings among Osteofibrous Dysplasia, Fibrous Dysplasia, and NonOssifying Fibroma of the Long Bone

Background The characteristics of magnetic resonance imaging (MRI) findings among osteofibrous dysplasia (OFD), fibrous dysplasia (FD), and nonossifying fibroma (NOF) have yet to be determined.

Aims This study determines the differences of MRI features among OFD, FD, and NOF of the long bone.

Patients and Methods This study included 39 patients including 10 OFD, 13 with FD, and 16 with NOF of the long bone. All patients underwent preoperative MRI and histological examination. We retrospectively reviewed the MRIs and compared the imaging findings among the three pathologies.

Results The maximum diameter was significantly different among OFD (47.0 ± 18.6 mm), FD (59.0 ± 35.0 mm), and NOF (33.3 ± 15.0 mm) (p < 0.05). Multiplicity (60%, p < 0.01), eccentric distribution (100%, p < 0.05), septation (70%, p < 0.01), homogeneous intensity on T2-weighted images (70%, p < 0.01), homogeneous contrast enhancement (63%, p < 0.05), and intense contrast enhancement (88%, p < 0.01) were significantly more frequent in OFD. Centric distribution (69%, p < 0.01), cyst formation (54%, p < 0.01), and fluid-fluid level formation (31%, p < 0.01) were significantly more frequent in FD. Eccentric distribution (100%, p < 0.01), heterogeneous on T2-weighted images (100%, p < 0.01), predominant hypointensity on T2-weighted images (44%, p < 0.01), and the presence of intralesional hypointensity on T2-weighted images (88%, p < 0.01) were significantly more frequent in NOF.

Conclusion MRI features could differentiate OFD, FD, and NOF of the long bone.

Imaging of Pediatric Bone Tumors and Tumor-like Lesions

Bone lesions are commonly seen when reporting pediatric skeletal imaging. Distinguishing aggressive from nonaggressive lesions is essential in making the diagnosis. Not all aggressive lesions are neoplastic; indeed, osteomyelitis frequently presents with aggressive appearances and is far more commonly seen in the pediatric population than neoplastic lesions. In this article, we discuss an approach for the diagnosis of pediatric bone tumors and tumor-like conditions. The most common pediatric benign and malignant bone tumors are discussed in more detail.

Hemangioma of long tubular bone: imaging characteristics with emphasis on magnetic resonance imaging

OBJECTIVE

To investigate the imaging findings, especially the MRI findings, of intraosseous hemangioma of long tubular bones and to improve the recognition of this rare tumor.

MATERIALS AND METHODS

The imaging characteristics of 16 histopathologically diagnosed long tubular bone hemangioma lesions were retrospectively reviewed on radiography (n = 16), CT (n = 16), and MRI (n = 15).

RESULTS

Thirteen of 16 lesions were intramedullary, whereas the other three were cortical, subperiosteal, and mixed intracortical and intramedullary, respectively. The radiologic appearance of long bone intraosseous hemangioma was divided into five types: cyst-like (n = 7), mesh- or honeycomb-like (n = 6), medullary sclerosis (n = 1), cortical thickening (n = 1), and cortical lytic type (n = 1). Radiography and CT allowed the identification of sclerotic margins in eight cases, thickened trabeculae in six cases, internal calcification in one case, cortical thickening in one case, and fracture in four cases. Two lesions were confusing on radiography but clearly identifiable on MRI. All intraosseous hemangioma showed high signal intensity on T2-weighted imaging and intermediate signal intensity on T1-weighted imaging. Four cyst-like lesions showed peripheral and filling enhancement, whereas others exhibited diffuse enhancement with an intensity similar to adjacent vessels.

CONCLUSION

Cystic and mesh types are the most common types of hemangioma in long tubular bones. MRI can help to define the location and extent of lesions. The tumor usually shows high signal intensity on T2-weighted imaging and intermediate signal intensity on T1-weighted imaging. Peripheral and filling or diffuse enhancement with an intensity similar to vessels is helpful for the diagnosis of intraosseous hemangioma.

Benign Osseous Tumors and Tumor-Like Conditions

We will provide an imaging-focused discussion of 3 benign bone tumors that do not fit in the categories of cartilaginous tumors or osteoid tumors. We have chosen giant cell tumor of bone, unicameral bone cyst, and fibrous dysplasia. All 3 of these entities are common enough that one does not have to be a musculoskeletal radiologist in a cancer hospital to encounter them occasionally, but none of them should be seen frequently.

Fibrous dysplasia limited to an ossicle

Fibrous dysplasia is an unusual pathologic condition caused by abnormal bone metabolism. Temporal bone involvement is often seen, but it is uncommon to find fibrous dysplasia limited to the middle ear, especially originating in and confined to a single ossicle. Here we report a case of osteofibrous dysplasia limited exclusively to an ossicle (malleus) causing gradual conductive hearing loss, which recovered after eventual complete removal of the dysplastic area. The lesion showed firm attachment to adjacent structures and initial removal was not possible. This report provides information to help other otologic surgeons facing similar conditions.