From the archives of AFIP. Imaging of giant cell tumor and giant cell reparative granuloma of bone: radiologic-pathologic correlation.

The radiologic features of giant cell tumor (GCT) and giant cell reparative granuloma (GCRG) of bone often strongly suggest the diagnosis and reflect their pathologic appearance. At radiography, GCT often demonstrates a metaepiphyseal location with extension to subchondral bone. GCRG has a similar appearance but most commonly affects the mandible, maxilla, hands, or feet. Computed tomography and magnetic resonance (MR) imaging are helpful in staging lesions, particularly in delineating soft-tissue extension. Cystic (secondary aneurysmal bone cyst) components are reported in 14% of GCTs. However, biopsy must be directed at the solid regions, which harbor diagnostic tissue. These solid components demonstrate low to intermediate signal intensity at T2-weighted MR imaging, a feature that can be helpful in diagnosis. Multiple GCTs, although rare, do occur and may be associated with Paget disease. Malignant GCT accounts for 5%-10% of all GCTs and is usually secondary to previous irradiation of benign GCT. Treatment of GCT usually consists of surgical resection. Recurrence is seen in 2%-25% of cases, and imaging is vital for early detection. Recognition of the spectrum of radiologic appearances of GCT and GCRG is important in allowing prospective diagnosis, guiding therapy, and facilitating early detection of recurrence.

Imaging of musculoskeletal fibromatosis.

The musculoskeletal fibromatoses comprise a wide range of lesions with a common histopathologic appearance. They can be divided into two major groups: superficial and deep. The superficial fibromatoses are typically small, slow-growing lesions and include palmar fibromatosis, plantar fibromatosis, juvenile aponeurotic fibroma, and infantile digital fibroma. The deep fibromatoses are commonly large, may grow rapidly, and are more aggressive. They include infantile myofibromatosis, fibromatosis colli, extraabdominal desmoid tumor, and aggressive infantile fibromatosis. Radiographs typically reveal a nonspecific soft-tissue mass, and calcification is common only in juvenile aponeurotic fibroma. Advanced imaging (ultrasonography, computed tomography, and magnetic resonance [MR] imaging) demonstrates lesion extent. Involvement of adjacent structures is common, reflecting the infiltrative growth pattern often seen in these lesions. MR imaging may show characteristic features of prominent low to intermediate signal intensity and bands of low signal intensity representing highly collagenized tissue. However, fibromatoses with less collagen and more cellularity may have nonspecific high signal intensity on T2-weighted images. Local recurrence is frequent after surgical resection due to the aggressive lesion growth. It is important for radiologists to recognize the imaging characteristics of musculoskeletal fibromatoses to help guide the often difficult and protracted therapy and management of these lesions.

Primary musculoskeletal tumors of fibrous origin.

Tumors of fibrous origin include fibrous dysplasia (FD), fibroxanthoma (nonossifying fibroma), cortical desmoid, desmoplastic fibroma, fibrosarcoma, and malignant fibrous histiocytosis (MFH). Benign fibrous lesions (FD, fibroxanthoma, and cortical desmoid) frequently demonstrate pathognomonic radiologic characteristics obviating the need for biopsy. Indeed, biopsy of these lesions can occasionally lead to confusion with more aggressive lesions. Desmoplastic fibroma and the malignant fibrous lesions (fibrosarcoma and MFH) often reveal nonspecific imaging features of a solitary nonmineralized lesion with aggressive characteristics. However, imaging is important as with other neoplasms in delineating the extent of involvement for staging purposes. This article reviews the spectrum of clinical characteristics, pathology, imaging appearances, treatment, and prognosis of lesions of fibrous origin in bone.

Lesions of unknown histogenesis: Langerhans cell histiocytosis and Ewing sarcoma.

Langerhans cell histiocytosis (LCH) and Ewing sarcoma represent lesions of unknown histogenesis. Both lesions typically affect children and adolescents. Imaging features frequently suggest the diagnosis, and both lesions may demonstrate aggressive characteristics. LCH shows a broader spectrum of imaging findings, depending on lesion activity and location, which are reviewed in this article. Ewing sarcoma typically reveals both osseous and soft tissue involvement, although direct continuity of the components is often not apparent. Knowledge of the spectrum of clinical and radiologic features facilitates early diagnosis and can be used to evaluate the effects of therapy.

Imaging of osteochondroma: variants and complications with radiologic-pathologic correlation.

Osteochondroma represents the most common bone tumor and is a developmental lesion rather than a true neoplasm. It constitutes 20%-50% of all benign bone tumors and 10%-15% of all bone tumors. Its radiologic features are often pathognomonic and identically reflect its pathologic appearance. Osteochondromas are composed of cortical and medullary bone with an overlying hyaline cartilage cap and must demonstrate continuity with the underlying parent bone cortex and medullary canal. Osteochondromas may be solitary or multiple, the latter being associated with the autosomal dominant syndrome, hereditary multiple exostoses (HME). Complications associated with osteochondromas are more frequent with HME and include deformity (cosmetic and osseous), fracture, vascular compromise, neurologic sequelae, overlying bursa formation, and malignant transformation. Malignant transformation is seen in 1% of solitary osteochondromas and in 3%-5% of patients with HME. Continued lesion growth and a hyaline cartilage cap greater than 1.5 cm in thickness, after skeletal maturity, suggest malignant transformation. Variants of osteochondroma include subungual exostosis, dysplasia epiphysealis hemimelica, turret and traction exostoses, bizarre parosteal osteochondromatous proliferation, and florid reactive periostitis. Recognition of the radiologic spectrum of appearances of osteochondroma and its variants usually allows prospective diagnosis and differentiation of the numerous potential complications, thus helping guide therapy and improving patient management.

Liposclerosing myxofibrous tumor: a radiologic-pathologic-distinct fibro-osseous lesion of bone with a marked predilection for the intertrochanteric region of the femur.

PURPOSE: To describe the characteristic features of liposclerosing myxofibrous tumor (LSMFT) of bone. MATERIALS AND METHODS: The radiographs and clinical histories of 39 patients (21 male, 18 female; mean age, 42 years; age range, 15-69 years) with histologically verified LSMFT of bone were retrospectively studied. RESULTS: LSMFT had a predilection for the proximal femur; more than 90% (30 of 33) of the femoral lesions were in the intertrochanteric region. Radiographs showed an indolent growth pattern with a well-defined and often extensively sclerotic margin. The bone contour either was normal or showed mild expansile remodeling. Mineralization within the lesion was not uncommon. Scintigrams showed mild to moderate focal tracer accumulation. Findings at computed tomography reflected those at radiography, whereas magnetic resonance imaging findings were nonspecific. Four (10%) patients had evidence of malignant transformation. CONCLUSION: The radiologic appearance of LSMFT in the intertrochanteric region of the femur is characteristic. The substantial prevalence of malignant transformation associated with LSMFT underscores the need for close observation of this lesion.

From the archives of the AFIP. Imaging of musculoskeletal neurogenic tumors: radiologic-pathologic correlation.

Numerous neurogenic tumors can affect the musculoskeletal system, including traumatic neuroma, Morton neuroma, neural fibrolipoma, nerve sheath ganglion, neurilemoma, neurofibroma, and malignant peripheral nerve sheath tumors (PNSTs). The diagnosis of neurogenic tumors can be suggested from their imaging appearances, including lesion shape and intrinsic imaging characteristics. It is also important to establish lesion location along a typical nerve distribution (eg, plantar digital nerve in Morton neuroma, median nerve in neural fibrolipoma, large nerve trunk in benign and malignant PNSTs). Traumatic and Morton neuromas are commonly related to an amputation stump or are located in the intermetatarsal space, respectively. Neural fibrolipomas show fat interspersed between nerve fascicles and are often associated with macrodactyly. Nerve sheath ganglion has a cystic appearance and commonly occurs about the knee. Radiologic characteristics of neurilemoma, neurofibroma, and malignant PNST at computed tomography (CT), ultrasonography, and magnetic resonance imaging include fusiform shape, identification of entering and exiting nerve, low attenuation at CT, target sign, fascicular sign, split-fat sign, and associated muscle atrophy. Although differentiation of neurilemoma from neurofibroma and of benign from malignant PNST is problematic, recognition of the radiologic appearances of neurogenic tumors often allows prospective diagnosis and improves clinical management of patients.

Subcutaneous granuloma annulare: radiologic appearance.

OBJECTIVE: Granuloma annulare is an uncommon benign inflammatory dermatosis characterized by the formation of dermal papules with a tendency to form rings. There are several clinically distinct forms. The subcutaneous form is the most frequently encountered by radiologists, with the lesion presenting as a superficial mass. There are only a few scattered reports of the imaging appearance of this entity in the literature. We report the radiologic appearance of five cases of subcutaneous granuloma annulare. DESIGN AND PATIENTS: The radiologic images of five patients (three male, two female) with subcutaneous granuloma annulare were retrospectively studied. Mean patient age was 6.4 years (range, 2-13 years). The lesions occurred in the lower leg (two), foot, forearm, and hand. MR images were available for all lesions, gadolinium-enhanced imaging in three cases, radiographs in four, and bone scintigraphy in one. RESULTS: Radiographs showed unmineralized nodular masses localized to the subcutaneous adipose tissue. The size range, in greatest dimension on imaging studies, was 1-4 cm. MR images show a mass with relatively decreased signal intensity on all pulse sequences, with variable but generally relatively well defined margins. There was extensive diffuse enhancement following gadolinium administration. CONCLUSION: The radiologic appearance of subcutaneous granuloma annulare is characteristic, typically demonstrating a nodular soft-tissue mass involving the subcutaneous adipose tissue. MR images show a mass with relatively decreased signal intensity on all pulse sequences and variable but generally well defined margins. There is extensive diffuse enhancement following gadolinium administration. Radiographs show a soft-tissue mass or soft-tissue swelling without evidence of bone involvement or mineralization. This radiologic appearance in a young individual is highly suggestive of subcutaneous granuloma annulare.

Focal myositis.

Focal myositis is a pseudotumor of soft tissue that typically occurs in the deep soft tissue of the extremities, and is a relatively rare lesion. There is a wide clinical spectrum, with approximately one-third of patients with focal myositis subsequently developing polymyositis, and clinical symptoms of generalized weakness, fever, myalgia, and weight loss, with elevation of creatine phosphokinase. We report the case of a patient with focal myositis who subsequently developed myositis ossificans-like features.

Magnetic resonance angiography of the hand and wrist: evaluation of patients with severe ischemic disease.

Conventional arteriography is considered the standard for the evaluation of patients with severe ischemic disease of the hand and wrist. Magnetic resonance (MR) has been shown to be a reliable noninvasive alternative to conventional arteriography. The authors prospectively evaluated this technology in 11 patients with Raynaud's syndrome and severe ischemic disease of the upper extremity. MR angiograms were compared with results from surgery in seven cases and conventional arteriography in four cases. There was excellent correlation between MR angiography and the results of surgery and conventional arteriography. In all cases, MR correctly predicted the patency or lack of patency of the distal and ulnar arteries, and superficial and deep palmar arches. In three cases, portions of the palmar arches oriented parallel to the plane were not adequately seen. Common and proper digital arteries were incompletely seen with both conventional and MR angiography. MR angiography is a reliable noninvasive method to evaluate patients with severe upper-extremity ischemic disease, accurately depicting the peripheral vessels through the level of the palmar arches. Anatomic vascular depiction is adequate for determination of patency of the major vessels for preoperative evaluation for reconstructive surgery and sympathectomy.

The many faces of osteosarcoma.

Osteosarcoma is the most common primary malignant tumor of bone in adolescents and young adults. It accounts for approximately 15% of all primary bone tumors confirmed at biopsy. There are numerous types of primary osteosarcoma, including intramedullary (high grade, telangiectatic, low grade, small cell, osteosarcomatosis, and gnathic), surface (intracortical, parosteal, periosteal, and high-grade surface), and extraskeletal. Osteosarcoma may also occur as a secondary lesion in association with underlying benign conditions. The identification of osteoid matrix formation and aggressive characteristics usually allows prospective radiologic diagnosis of osteosarcoma. As with all bone tumors, differential diagnosis is best assessed with radiographs, whereas staging is performed with computed tomography or magnetic resonance imaging. Understanding and recognition of the variable appearances of the different varieties of osteosarcoma allow improved patient assessment and are vital for optimal clinical management including diagnosis, biopsy, staging, treatment, and follow-up.

The use of gadolinium in the MR evaluation of soft tissue tumors.

MRI has emerged as the preferred modality for the imaging evaluation of musculoskeletal tumors. Although there is general agreement on the value of MR in detection, diagnosis and staging, the use of intravenous contrast in the evaluation of soft-tissue tumors and tumor-like masses remains controversial. The purpose of this review is to highlight these controversies, to put them in perspective, and to make recommendations for the use of gadolinium-enhanced imaging. The following specific areas will be addressed: (1) general considerations in the evaluation of soft tissue tumors, (2) added specificity in diagnosis, (3) response to chemotherapy, (4) evaluation for local recurrence after surgery and/or radiation therapy, and (5) selection of biopsy site.

Parosteal osteosarcoma: value of MR imaging and CT in the prediction of histologic grade.

PURPOSE: To evaluate the use of magnetic resonance (MR) imaging and computed tomography (CT) for predicting the histologic grade of parosteal osteosarcomas. MATERIALS AND METHODS: Sixty parosteal osteosarcomas were analyzed for tumor size and location, presence of a cleavage plane, intramedullary extension, soft-tissue mass (distinct from ossified mass), and the presence and pattern of ossification. Axial and longitudinal views were evaluated for specific osseous sites within the bone. Tumors were classified as low grade (grade 1) or high grade (grades 2-3). RESULTS: There were 32 low-grade lesions and 28 high-grade lesions. Average maximal lengths of low- and high-grade tumors were 7.7 and 15.0 cm, respectively. A cleavage plane was present in 20 (62%) low-grade and 19 (68%) high-grade lesions. On cross-sectional images, intramedullary extension was present in 13 (41%) low-grade and 14 (50%) high-grade lesions. A focal soft-tissue mass distinct from the ossific matrix was identified in 25 (89%) high-grade lesions and in only two (6%) low-grade lesions. All 17 high-grade lesions evaluated with MR imaging were of predominantly high signal intensity on T2-weighted images. CONCLUSION: A poorly defined soft-tissue component distinct from the ossific matrix is the most distinctive feature of high-grade parosteal osteosarcoma and may be an optimal site for biopsy.

Percutaneous transpedicular biopsy of vertebral body lesions.

STUDY DESIGN: This prospective study evaluates the use of transpedicular biopsy in obtaining diagnostic tissue from vertebral body lesions. OBJECTIVE: To report the authors' experience of all (N = 32) percutaneous transpedicular biopsies performed between 1990-1994. SUMMARY OF BACKGROUND DATA: Previous articles have discussed the value of open biopsy of the vertebral body using a Craig needle. A large series of closed percutaneous transpedicular biopsies have not been reported. METHODS: The authors evaluated 32 patients (26 outpatients, six inpatients) who underwent transpedicular biopsy for T1-L4 lesions of the vertebral bodies. None of the tumors had an extraosseous component. Biopsy specimens were obtained from 25 lesions using C-arm fluoroscopy; seven were guided by computed tomography. All biopsies were performed with a 14- to 17-gauge bone biopsy needle. RESULTS: The needle passed through the pedicle into the site of disease in all patients, as confirmed by C-arm fluoroscopy or computed tomography. There were 22 malignancies; four isolated compression fractures, two at T6, one at T7, one at T8; four cases of infection or inflammation; and one case each of Paget's disease and myelofibrosis. Two patients required a second biopsy because the tissue sample was suspicious for lymphoma but not diagnostic. All 26 outpatients were discharged after a 2-hour observation period. There were no complications. CONCLUSION: Transpedicular biopsy of deep vertebral body lesions using a bone biopsy needle under computed tomography or fluoroscopy guidance can be performed safely and efficaciously as an outpatient procedure.

The use of gadolinium in the MR evaluation of musculoskeletal tumors.

Magnetic resonance (MR) imaging has emerged as the preferred modality for the imaging evaluation of musculoskeletal tumors. Although there is general agreement on the value of MR in diagnosis and staging, the use of intravenous contrast in the evaluation of musculoskeletal lesions remains controversial. The purpose of this review is to highlight these controversies, to put them in perspective, and to suggest recommendations for the use of gadopentetate dimeglumine. The following specific areas will be addressed: (a) evaluation of soft-tissue tumors, (b) diagnosis of low-grade chondrosarcoma and the use of contrast material in identification of intraosseous metastases, (c) monitoring response to chemotherapy, (d) evaluation for local recurrence after surgery and/or radiation therapy, and (e) selection of biopsy site.

MR imaging of soft-tissue masses. Mass-like lesions that simulate neoplasms.

The MR appearance of soft-tissue masses that simulate neoplasms has been described. In some cases, radiographs may demonstrate characteristic findings in association with MR imaging that may be diagnostic, such as an ossific rim seen in myositis ossificans, periosteal reaction seen in fibro-osseous pseudotumor, and retained foreign bodies present in a foreign body reaction or abscess. In other cases, the characteristic lesion location, age of the patient, and clinical presentation may be suggestive of the diagnosis, as in elastofibroma and nodular fasciitis.