The role of magnetic resonance imaging in the diagnostic evaluation of malignant peripheral nerve sheath tumors

BACKGROUND AND AIMS

Malignant peripheral nerve sheath tumors (MPNSTs) are the leading cause of mortality in patients with neurofibromatosis type-1 (NF1)); however, they may also arise sporadically. Differences in magnetic resonance imaging (MRI) features between MPNSTs arising in NF1 subjects versus non-NF1 subjects have not been studied before. The accuracy of MRI in distinguishing MPNSTs from benign peripheral nerve sheath tumors (BPNSTs) has also been debated. The objective of this study was to determine the potential differentiating MRI features between (a) NF1-related and non-NF1-related MPNSTs and (b) MPNSTs and BPNSTs.

MATERIALS AND METHODS

We retrospectively evaluated the MRI studies of 21 patients (12 NF1 subjects and nine non-NF1 subjects) with MPNSTs and 35 patients with BPNSTs. In all studies, the lesions were assessed in terms of size, margins, T1 and T2 signal characteristics, internal architecture, pattern of contrast enhancement, invasion of adjacent structures and necrosis/cystic degeneration as well as for the presence of tail-, target- and split-fat signs.

RESULTS

MPNSTs of NF1 subjects occurred at an earlier age and displayed a higher incidence of necrosis/cystic degeneration compared with MPNSTs of non-NF1 subjects. Compared with BPNSTs, MPNSTs were significantly larger at the time of diagnosis and demonstrated a higher incidence of ill-defined margins (specificity 91%, sensitivity 52%) and invasion of adjacent structures (specificity 100%, sensitivity 43%).

CONCLUSIONS

Differences exist between NF1-related and non-NF1-related MPNSTs regarding the age of occurrence and MRI appearance. In the MRI evaluation of peripheral nerve sheath tumors, the presence of ill-defined tumor margins and/or invasion of adjacent structures are highly specific for malignancy.

Ethical decision-making about older adults and moral intensity: an international study of physicians

Through discourse with international groups of physicians, we conducted a cross-cultural analysis of the types of ethical dilemmas physicians face. Qualitative analysis was used to categorise the dilemmas into seven themes, which we compared among the physicians by country of practice. These themes were a-theoretically-driven and grounded heavily within the text. We then subjected the dilemmas to an analysis of moral intensity, which represents an important (albeit novel within healthcare research) theoretical perspective of ethical decision making. These constructs (ie, culture and moral intensity) represent salient determinants of ethical behaviour and our cross-cultural sample afforded us the opportunity to consider both the pragmatic aspects of culture, as they are perceived by physicians, as well as the theory-driven concept of moral intensity. By examining both culture and moral intensity, we hope to better elucidate the complexities of ethical decision-making determinants among physicians in their daily practice. Doing so may potentially have practical implications for ethics training of medical students and foreign physicians.

Hyperphosphatasia with massive osteoectasia: a 45-year follow-up

Hyperphosphatasia is a heterogeneous group of disorders characterized by a generalized skeletal disease and increased alkaline phosphatase. Increased bone remodeling secondary to increased osteoclastic activity appears to be the underlying feature of these disorders. These disorders include juvenile Paget's disease, expansile skeletal hyperphosphatasia, hyperostosis generalisata with striations, and Camurati-Engelmann's disease, type II. The genetic mutations for a number of these disorders have been identified. We present a patient with congenital hyperphosphatasia whose clinical and radiographic features were somewhat different from these other well-defined syndromes. The patient was followed for 45 years until his death of at age 49. The patient had massive osteoectasia with dense striations involving the entire shaft of his long bones. His spine, pelvis, short tubular bones, and calvarium were also involved. He suffered hearing loss and optic atrophy, but he kept his teeth throughout his life. He was tall with a marfanoid habitus, and he had hypogonadism and hypothyroidism. There was no evidence of mental retardation, and other laboratory studies where within normal limits. This case, as well as other manifestations of hyperphosphatasia, attests to the complexity of the bone remodeling system.

Intraosseous lipoma of the left frontoethmoidal sinuses and nasal cavity

Intraosseous lipomas are very rare slow-growing benign tumors that may appear as congenital lesions or may be acquired (metaplasia from a pre-existing lipoma). Only a handful of head and neck cases have been reported in the literature. We present the first reported case of a solitary osteolipoma involving the sinonasal tract in a 66-year-old man with sinonasal symptoms. CT showed a lesion involving the left frontal sinus, extending into the ethmoid sinus with insinuation along the left middle turbinate. It appeared to be an atypical mass with areas of high attenuation (calcification) within.

Isolated lower extremity metastases, 9 years after initial diagnosis of retinoblastoma

We report the development of isolated lower extremity metastases, in a child, 9 years after her initial diagnosis and treatment of bilateral infantile retinoblastomas. The radiographic, scintigraphic, computed tomographic, and magnetic resonance imaging findings are discussed. The dominant metastatic focus was blastic, involving the medial cuneiform. Additional occult lesions were found in the base of the second metatarsal, middle cuneiform, navicular and tibial diaphysis. An open biopsy confirmed the diagnosis. The occurrence of late distant metastases is rare in the USA.

Ewing's sarcoma presenting as a solitary cyst

This case describes a 10-year-old girl who developed a Ewing's sarcoma in her proximal fibula. The radiologic features mimicked those of a unicameral bone cyst. The presence of pain and the atypical location led to a prompt biopsy and the correct diagnosis. The mechanism of this unusual radiographic presentation is discussed.

Intracortical chondroma: a report of two cases

Intracortical chondromas are exceedingly rare lesions that have the histopathologic appearance of enchondromas, but are located within cortical bone. Two new cases of intracortical chondroma, one symptomatic and the other found incidentally, are presented and the entity's brief literature reviewed.

Oromaxillofacial osseous abnormality in Sturge-Weber syndrome: case report and review of the literature

We report a case of a 17-month-old child affected by Sturge-Weber syndrome who had unusually rapid overgrowth of the left frontal, temporal, orbital, and maxillary regions. CT angiography illustrated osteohypertrophy with periostitis and associated soft tissue hypertrophy directly corresponding to the distribution of the cutaneous port-wine stain. Extended maxillectomy was performed because of rapid growth and clinical debilitation, with surgical pathology revealing juvenile ossifying fibroma.

Heterotopic ossification: a review

Heterotopic ossification is the formation of bone in the soft tissues. Soft tissue bone deposition may range from the minimal and inconsequential to massive and clinically significant. In some clinical settings it is a predictable finding with an unpredictable course and in other settings it may be diagnostically confounding. Heterotopic ossification may be encountered in clinically disparate disease processes and circumstances. We review the genetic, neurogenic, post-traumatic, post-surgical and "reactive" causes of heterotopic ossification and discuss some current concepts of its pathogenesis.

The effect of intravenous pamidronate on bone mineral density, bone histomorphometry, and parameters of bone turnover in adults with type IA osteogenesis imperfecta

The type IA osteogenesis imperfecta (OI) phenotype is characterized by multiple fractures, blue sclerae, and minimal skeletal deformity without dentinogenesis imperfecta. The object of this study was to determine the effect of treatment with intravenous pamidronate (30 mg) every 3 months on bone density and bone histomorphometry in adults with type IA OI. After an initial iliac crest bone biopsy eight subjects, 5 women and 3 men, entered a treatment program lasting 21-30 months. Five subjects, all women, completed the study which included a posttreatment iliac crest bone biopsy. Pamidronate treatment led to significant increases in bone mineral density (BMD), measured by DXA, in the lumbar spine at 12 months (P = 0.05) and in the femur neck (P = 0.02) at 24 months. Significant increases in BMD were also seen in femoral trochanter at 12 months (P = 0.05) and at 24 months (P = 0.02), and in Ward's triangle at 12 months (P = 0.02) and 24 months (P = 0.05). Mean osteocalcin levels decreased 32%, C-terminal procollagen peptide and bone alkaline phosphatase declined 12% and 47% at 15 and 21 months, respectively. Deoxypyridinoline crosslink excretion decreased 31%. Posttreatment bone biopsy revealed a significant 6.3% increase in mean bone trabecular volume (P = 0.01). Mean cortical thickness increased from 848 mm to 1384 mm (P = 0.01) and cortical porosity decreased 13.2% (P = 0.01). Bone formation rate increased significantly in all 5 patients from 6.6 to 15.3 mm2/yr (P = 0.01). Mineral apposition rate was unchanged. These results indicate that intravenous pamidronate, 30 mg every 3 months, may have significant effects on bone density and histomorphometry in adults with type IA OI. Responses at higher doses remain to be evaluated.

Fibrous dysplasia involving the skull base and temporal bone

OBJECTIVE

To gain a broader appreciation of the clinical presentation, operative treatment, and outcome of patients with fibrous dysplasia involving the skull base.

DESIGN

Retrospective review of a clinical case series.

SETTING

A single tertiary academic medical center.

PATIENTS

Twenty-one patients with histopathologically confirmed fibrous dysplasia involving the skull base cared for over a 15-year-period (1983-1998).

MAIN OUTCOME MEASURES

Clinical and radiographic location of the fibrous dysplasia lesions within the skull base, clinical presentation, surgical intervention, and clinical outcome were tabulated for each patient.

RESULTS

The ethmoids were most commonly involved (71%), followed by the sphenoid (43%), frontal (33%), maxilla (29%), temporal (24%), parietal (14%), and occipital (5%) bones. The most common presenting features included atypical facial pain and headache, complaints referable to the sinuses, proptosis and diplopia, hearing loss, and facial numbness. Surgical treatment, guided by clinical presentation, ranged from simple biopsy with conservative follow-up to craniofacial resection.

CONCLUSIONS

Fibrous dysplasia can present in myriad ways within the skull base. Modern imaging modalities and histopathologic analysis have made diagnosis relatively straightforward. Surgery, particularly in such a challenging region as the skull base, should be reserved for patients with functional impairment or a cosmetic deformity. Because of the benign nature of the condition, the surgery itself should be relatively conservative, with the primary goal being preservation of existing function.

A brachial plexopathy due to myositis ossificans. Case report and review of the literature

Myositis ossificans (MO) is a disorder characterized by the intramuscular proliferation of fibroblasts and osteoblasts, with subsequent deposition of bone and cartilage. A typical clinical presentation involves traumatic injury to a young adult, usually localized to the thigh, buttock, or upper arm, with resultant MO and mildly restricted range of motion in adjacent joints. Rarely, MO is associated with peripheral neuropathies involving the radial, median, sciatic, and sural nerves. The authors present an unusual case of MO causing a brachial plexopathy. To their knowledge, this is the first description of such a presentation.

Tumoral calcinosis of the spine: a study of 21 cases

STUDY DESIGN

A retrospective study was conducted to investigate 21 patients found during spinal surgery to have paraspinal masses of dystrophic calcification (tumoral calcinosis).

OBJECTIVES

To determine the magnetic resonance imaging characteristics of this disorder, and to document the associated spinal pathology.

SUMMARY OF BACKGROUND DATA

Tumoral calcinosis usually is associated with hereditary disorders of calcium metabolism or renal dialysis. It also occurs in degenerated tissues in the absence of systemic disorders. Characteristically, calcific masses in the appendicular skeleton are visible on plain radiographs. Tumoral calcinosis has only rarely been reported in the spine. Documented patients have had an obvious calcific mass, and almost always the disorder has existed in other locations as well. Careful histologic study of specimens removed during spinal surgery suggests that tumoral calcinosis is common in the spine and usually is secondary to preexisting pathology.

METHODS

This study involved 21 patients with lesions of tumoral calcinosis identified by histopathologic analysis of specimens removed during spinal surgery. The magnetic resonance images and the plain radiographs of the patients were reviewed and correlated with their clinical histories.

RESULTS

In all the patients, the lesion of tumoral calcinosis was associated with a mass lesion seen on magnetic resonance imaging. Calcific masses were not apparent on plain films. In no case was the mass diagnosed before surgery as tumoral calcinosis. The magnetic resonance imaging changes were variously misinterpreted as neoplasms, infections, extruded disc material, or cysts. The observed features of tumoral calcinosis were those of an extradural mass showing a heterogeneous mixed-signal lesion that was identical on T1- and T2-weighted images. Characteristically, gadolinium did not enhance the lesions.

CONCLUSIONS

Awareness of tumoral calcinosis of the spine may prevent unwarranted diagnoses of a more serious lesion in patients with characteristic magnetic resonance imaging changes. Also, this awareness may prevent pathologists from interpreting lesional tissue as nondiagnostic when other diagnoses are suspected clinically. This process may be a manifestation of degenerative spinal disease that has become so dominant that the underlying processes are obscured.

Disproportionately severe calcinosis cutis in an 88-year-old patient with CREST syndrome

An 88-year-old woman with CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasias) presented with hyperglycemia, intravascular depletion, and atrial fibrillation. The patient was found to have unusually severe calcinosis cutis in both legs extending from the knees to the ankles bilaterally, as well as Raynaud's phenomenon, sclerodactyly, and telangiectasias. The patient was normocalcemic and normophosphatemic. Although subcutaneous calcification is often seen with CREST syndrome, this case is unusual in that the area of involvement was much larger than previously described. Furthermore, the amount of calcinosis was disproportionately severe and was the major cause of symptoms and disability compared with the other components of the syndrome.

The role of MR imaging in soft tissue tumor evaluation: perspective of the orthopedic oncologist and musculoskeletal pathologist

Soft tissue masses are common in both children and adults. Clinicians must evaluate patients carefully to avoid management errors. The most effective management decisions are made when a working group composed of clinicians, radiologists, and pathologists participates in the interpretation of the imaging studies. Plain-film radiographs and MR imaging scans are the two main imaging modalities used in patients with soft tissue masses. The working group assimilates the clinical and radiographic data to determine if they can identify the nature of the soft tissue mass. When the group can assign a definitive diagnosis, the lesion is designated as a determinate lesion. Determinate lesions include lipomas, ganglions, hemangiomas, neurofibromas, diabetic myonecrosis, muscle tears, myositis ossificans (heterotopic ossification), and pigmented villonodular synovitis. When the process cannot be identified, the lesion is classified as indeterminate. All soft tissue sarcomas are indeterminate lesions. Many benign lesions are also indeterminate. Common examples include schwannomas, myxomas, and giant cell tumor of tendon sheath. Based on the clinical and radiologic features, these diagnoses may be suspected, but because of the inability to distinguish them from sarcomas based on the MR imaging features, they are usually classified as indeterminate. When lesions are judged to be determinate, observation or excisional biopsy are the two major treatment choices. When lesions cannot be identified on the imaging studies, incisional or needle biopsy is performed to establish a diagnosis. Once a diagnosis is made, the proper management choice can be selected. Inappropriate excisional biopsy is the major treatment error in the management of soft tissue tumors. When a high-grade soft tissue sarcoma is resected with multiple positive margins, the risk of local failure after definitive resection is much higher than if the patient had been treated initially with only a needle or incisional biopsy. Also, if a major complication, such as an infection, a major wound-healing problem, or contamination of the major neurovascular structures, occurs at the time of incisional biopsy, amputation of the limb may be necessary. Inappropriate excisional biopsy can occur when a surgeon is not familiar with the features of sarcomas or when a radiologist mistakenly interprets the signal features as a benign lesion.

Synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome presenting as a primary calvarial lesion. Case report and review of the literature

The synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a recently described, currently evolving clinical entity that groups together several idiopathic disorders of bone and skin formerly described under a variety of names. Among the spectrum of possible locations for the bone lesions, there is no previous report in the literature of primary involvement of the skull vault. A patient with primary involvement of the calvaria in the setting of SAPHO syndrome is described here, which, to the authors' knowledge, is the first report of such localization. The clinically and radiologically benign evolution of the different stages of the bone lesions is presented. The authors suggest that the SAPHO syndrome should be considered in the differential diagnosis of lytic, sclerotic, or hyperostotic lesions of the skull, particularly before considering invasive diagnostic procedures.

Soft-tissue masses: when and how to biopsy

Patients with soft-tissue tumors present a diagnostic challenge to the clinician. A systematic approach to evaluation and biopsy is necessary to minimize diagnostic errors and biopsy complications. With MRI, the clinician and radiologist are able to precisely identify some soft-tissue masses, such as lipomas, ganglions, hemangiomas, and popliteal cysts. Most soft-tissue tumors have signal characteristics that are low signal on T1-weighted images and high signal on T2-weighted images. Soft-tissue masses that cannot be identified are called indeterminate masses, and a biopsy is necessary to identify these lesions. Needle biopsy and open incisional biopsy are effective methods to histologically identify the nature of the tumor. Open excisional biopsy should be performed only when the surgeon knows that the soft-tissue lesion is benign.

Case of an ivory vertebra

The differential diagnosis of an osteoblastic vertebral lesion (ivory vertebra) includes metastatic prostate cancer, lung cancer, lymphoma, osteosarcoma and Paget's disease. We report a case of a man who was initially diagnosed with Paget's disease on vertebral biopsy. He failed to respond to conventional bisphosphate therapy. The review of the original biopsy specimen showed metastatic carcinoid tumor involving the bone marrow. The various features of carcinoid tumors metastasizing to the skeleton are briefly reviewed.

Primary resective shortening followed by distraction osteogenesis for limb reconstruction: a comparison with simple lengthening

Resective distraction osteogenesis is a new approach to treat segmental diaphyseal bone defects by primary limb shortening and secondary distraction osteogenesis from the same site. A rabbit model was introduced to compare the bone-regeneration characteristics of this technique with those of simple lengthening procedures. Twenty-four skeletally mature New Zealand White rabbits were divided into two equal groups. In the test group, limbs were lengthened after a 10-mm segmental diaphyseal bone resection and limb shortening. In the control group, a simple subperiosteal osteotomy for limb lengthening was performed without resection. New bone formation was evaluated mechanically, radiologically, histomorphometrically, and densitometrically. Bone bridging occurred in all animals. Normalized mechanical values for the newly reconstructed tibiae demonstrated similar torsional stiffness (71+/-3.3 compared with 71+/-8.2%; p = 0.95) and strength (64+/-5.3 compared with 68+/-7.3%; p = 0.66) in the two groups. The average normalized callus diameter was significantly greater in the test group than in the control group (p < 0.01). The remodeling index calculated from densitometry, however, showed a significantly less progressed stage of remodeling in the test group (p < 0.05). Histomorphometric analysis of the callus center supported this finding, showing significantly lower values for trabecular thickness (p < 0.05) and total bone volume (p < 0.01) in the test group. The results demonstrated the possibility of new bone formation after resection and monofocal shortening. This suggests a new therapeutic option to treat diaphyseal segmental bone defects.

Pathologic features in steroid and nonsteroid associated osteonecrosis

Multiple pathophysiologies for osteonecrosis have been postulated and various associated risk factors defined for this disease. However, the pathologic findings of the end stage disease are thought to be similar in all patients. To the author's knowledge, there are no data in the literature comparing the pathologic characteristics of osteonecrosis in a quantitative manner between groups of patients with different associated risk factors. The current study examined the pathologic features of core decompression specimens from the femoral head in a group of patients with osteonecrosis associated with corticosteroid therapy and compared them with specimens from patients with osteonecrosis with no history of corticosteroid therapy. The study group comprised 65 patients (96 hips); 45 patients (68 hips) in the corticosteroid group and 20 patients (28 hips) in the noncorticosteroid group. In the corticosteroid group, 65% of dead bone was identified histologically (44 of 68) as compared with 46% (13 of 28) in the noncorticosteroid group. Specimens staged according to the histologic grading system of Arlet and Durroux revealed the corticosteroid group had a higher incidence of late stage lesions than did the noncorticosteroid group. This was found even though the two groups had similar radiographic staging distribution. The hips in patients who used alcohol were comparable pathologically to the hips in patients who used corticosteroids. This study emphasizes that the histologic features of necrosis and repair are similar in corticosteroid and noncorticosteroid osteonecrosis. However, there were differences in the distribution of viable bone and pathologic stage of the lesions in the two groups, suggesting a more rapid evolution of changes in the corticosteroid group.

Pigmented villonodular synovitis of the hip and knee

Pigmented villonodular synovitis is an uncommon disease that remains a diagnostic challenge. Presenting complaints commonly involve one joint, most often the knee or hip. Symptoms of pain and swelling characteristically have an insidious onset and are slowly progressive. The physical examination may be completely normal. Radiographs of the knee may appear normal or may show a periarticular soft tissue density, expansion of the suprapatellar pouch and local osseous changes confined to the patellofemoral articulation. Radiographs of the hip may show erosions in the head and neck of the femur and acetabulum. Magnetic resonance imaging usually demonstrates key diagnostic features, which include joint effusion, elevation of the joint capsule, hyperplastic synovium and low signal intensity resulting from hemosiderin deposition. The diagnosis of pigmented villonodular synovitis is confirmed by biopsy, and the treatment of choice is synovectomy.

Lytic Paget disease as a cause of orbital cholesterol granuloma

A case of histologically confirmed Paget disease of the orbit produced a lesion that appeared both clinically and histologically similar to a cholesterol granuloma. This case is unique because of the unusual location of the lesion, its presentation in a patient with no other manifestations of Paget disease, and the histological picture produced by the disease.

A 15-month evaluation of the effects of repeated subgingival minocycline in chronic adult periodontitis

BACKGROUND

A double-blind, randomized, parallel, comparative study was designed to evaluate the long-term safety and efficacy of subgingivally administered minocycline ointment versus a vehicle control.

METHODS

One hundred four patients (104) with moderate to severe adult periodontitis (34 to 64 years of age; mean 46 years) were enrolled in the study. Following scaling and root planing, patients were randomized to receive either 2% minocycline ointment or a matched vehicle control. Study medication was administered directly into the periodontal pocket with a specially designed, graduated, disposable applicator at baseline; week 2; and at months 1, 3, 6, 9, and 12. Scaling and root planing was repeated at months 6 and 12. Standard clinical variables (including probing depth and attachment level) were evaluated at baseline and at months 1, 3, 6, 9, 12, and 15. Microbiological sampling using DNA probes was done at baseline; at week 2; and at months 1, 3, 6, 9, 12, and 15.

RESULTS

Both treatment groups showed significant and clinically relevant reductions in the numbers of each of the 7 microorganisms measured during the entire 15-month study period. When differences were detected, sites treated with minocycline ointment always produced statistically significantly greater reductions than sites which received the vehicle control. For initial pockets > or =5 mm, a mean reduction in probing depth of 1.9 mm was seen in the test sites, versus 1.2 mm in the control sites. Sites with a baseline probing depth > or =7 mm and bleeding index >2 showed an average of 2.5 mm reduction with minocycline versus 1.5 mm with the vehicle. Gains in attachment (0.9 mm and 1.1 mm) were observed in minocycline-treated sites, with baseline probing depth > or =5 mm and > or =7 mm, respectively, compared with 0.5 mm and 0.7 mm gain at control sites. Subgingival administration of minocycline ointment was well tolerated.

CONCLUSIONS

Overall, the results demonstrate that repeated subgingival administration of minocycline ointment in the treatment of adult periodontitis is safe and leads to significant adjunctive improvement after subgingival instrumentation in both clinical and microbiologic variables over a 15-month period.

Osteosarcoma of the head and neck: a review of the Johns Hopkins experience

OBJECTIVE

To determine factors including treatment modalities which influence survival in patients with osteosarcoma of the head and neck.

STUDY DESIGN

Retrospective clinicopathologic study of 27 patients with osteosarcoma of the head and neck.

METHODS

The clinical charts and pathology slides were reviewed on 27 patients who had osteosarcoma of the head and neck between 1946 and 1998. The following variables were examined for their effect on survival: age of diagnosis, site of tumor, presentation, race, sex, prior radiation exposure, retinoblastoma history, margin status, and method of treatment.

RESULTS

The average age at the time of diagnosis of the patients was 37.6 years (range, 7-82 y). The sex distribution was similar with 14 male and 13 female patients. Eight of 27 patients had osteosarcoma of the mandible, 9 of 27 had osteosarcoma of the maxilla and paranasal sinuses, and in 10 of 27 patients osteosarcoma occurred elsewhere, including the temporal bones, occipital bones, and orbit. The overall 2-year survival was 66% with a 5-year survival rate of 55%.

CONCLUSIONS

Positive surgical margins and a high tumor grade were found to have a statistically deleterious effect on overall survival. There was no detectable effect on survival of age, race, sex, prior radiation exposure, tumor site, and tumor cell type. It was not possible to differentiate between the different adjuvant treatment modalities because of the small numbers in the study.

Endovascular papillary angioendothelioma (Dabska tumor) of bone

Endovascular papillary angioendothelioma, also known as Dabska tumor, is a rare vascular neoplasm that usually involves the skin or subcutaneous tissue of children. There have been no reported cases of this lesion occurring in bone. We report a Dabska tumor in the distal femur of a 45-year-old woman who, clinically and radiologically, was felt to have an osteoid osteoma. Histologic study of the lesion showed a hemangioma with budding fronds of endothelial cells, a feature characteristic of the Dabska tumor. We feel that the lesion arose in a pre-existing hemangioma, a hypothesis suggested in a few other case reports. Endovascular papillary angioendothelioma is a low-grade malignant neoplasm, although only one patient has died due to this lesion. Our patient is asymptomatic without evidence of recurrence 1 year post curettage.

The pathology of transient regional osteoporosis

Biopsy specimens from 19 patients with transient regional osteoporosis were studied. All patients presented with pain. There were nine patients with transient osteoporosis of the hip. Six of these specimens were therapeutic core biopsies, and three were femoral heads removed during total hip replacement. The other patients with osteoporosis in different locations had biopsies to rule out infection or neoplasm. Five of these patients had transient osteoporosis of the knee. Three had ankle involvement and two had involvement of the tibial shaft. Plain radiographs were available for study in all cases, and either a bone scan or an MRI was studied in each case. Except for one patient who was lost to follow-up, all had resolution of symptoms and radiographic changes. The histologic changes in the biopsies were distinctive, although they were present in varying degrees. There was edema and reactive bone formation in the marrow spaces. In addition, osteoclastic bone resorption was active in 14 of the 19 cases. Although lipid cysts were sometimes found in the marrow spaces, there was no evidence of fat necrosis or bone necrosis. The high bone turnover and absence of fat necrosis suggests that this disorder is a vasomotor response rather than an early stage of osteonecrosis. Awareness of these characteristic histologic changes should enable the pathologist to make a specific diagnosis of transient regional osteoporosis when a biopsy is required.

Histopathologic correlates of a positive bone scan

The accumulation of radioactive tracer is associated with specific histological changes. Awareness of these changes permits a more specific interpretation of a positive bone scan, especially when correlating the radionuclide image with the plain radiographs. Increased uptake in the flow phase of an imaging study usually corresponds to differentiated vascular spaces. In the blood pool phase, tracer accumulation is caused by neovascularity, a feature of reactive granulation tissue or neoplastic angiogenesis. In the delayed phase, tracer uptake is attributable to osteoid production. With plain radiographic correlation, the manner of osteoid deposition--remodeling, endochondral, reactive, or neoplastic--can be determined. The knowledge of these histological features may help the nuclear radiologist make the correct diagnosis.

Bone histomorphometry in adults with type IA osteogenesis imperfecta

A histologic and histomorphometric analysis was performed on undecalcified bone from 8 adult patients, ages 34 to 64 years, with Type IA osteogenesis imperfecta. Complete histomorphometric data, including static and dynamic parameters of bone remodeling, could be generated on 6 patients, and partial data were obtained from the other 2 patients. Findings in some patients of reduced eroded surfaces and reduced osteoid surfaces suggested low bone turnover. Other findings included normal or slightly reduced labeled surfaces, slightly reduced bone formation rate, decreased cortical thickness, and decreased bone volume. Histologic examination results showed lamellar bone with mature cortical Haversian systems. Trabeculae showed qualitatively normal connectedness despite low trabecular volume. The finding of normal or reduced bone turnover in adults with Type IA osteogenesis imperfecta has not been reported. Earlier histomorphometric studies, performed without correlation with a specific age or phenotype, indicated high bone turnover. The present study suggests that future research should correlate histopathologic changes with specific phenotypes. The finding of normal or slightly reduced bone turnover in Type IA osteogenesis imperfecta may have important therapeutic implications for this phenotype.

Benign and malignant musculoskeletal masses: MR imaging differentiation with rim-to-center differential enhancement ratios

PURPOSE

To assess the diagnostic potential of the rim-to-center differential enhancement ratio in the magnetic resonance (MR) imaging differentiation of benign from malignant musculoskeletal masses.

MATERIALS AND METHODS

Dynamic gadolinium-enhanced fast multiplanar spoiled gradient-recalled acquisition in the steady state imaging was performed to evaluate 17 one and soft-tissue masses (10 malignant, seven benign) in 14 patients. The rim-to-center differential enhancement ratio was determined from images at the maximal enhancement rate. The difference in differential enhancement ratios between benign and malignant masses was evaluated and compared with the maximum rate of enhancement for each mass.

RESULTS

Nine of 10 malignant masses showed rapid rim enhancement with delayed central fill-in. This enhancement pattern was absent in benign masses. The average rim-to-center differential enhancement ratio was 0.64 +/- 0.26 for malignant masses and -0.16 +/- 0.33 for benign masses (P < .001). This difference was statistically significant. The average maximum rate of enhancement was 3.41%/sec +/- 2.20 for malignant masses and 2.74%/sec +/- 2.46 for benign masses (P > .05).

CONCLUSION

Intratumoral enhancement patterns of malignant and benign masses differ because of differences in vascular architecture. These preliminary results suggest that the rim-to-center differential enhancement ratio has potential as an additional parameter for the MR imaging differentiation of indeterminate musculoskeletal masses.

Bilateral osteofibrous dysplasia: a report of two cases and review of the literature

Images

Clinicopathologic features and treatment of osteoid osteoma and osteoblastoma in children and adolescents

Benign bone-forming tumors are common in children. Careful radiographic imaging is necessary to plan surgical treatment. Careful histologic study is necessary to distinguish osteoblastoma from more aggressive tumors. Osteoid osteoma should be considered when the child or adolescent presents with pain in an extremity or along the spine.

Ki-67 immunostaining as a tool in the diagnosis of central cartilage lesions

Images