Diffuse mineralization of extraskeletal chondroma: a case report

We report a case of extraskeletal chondroma involving diffuse hazy calcification of the chondroid matrix. T2-weighted magnetic resonance imaging showed a well-defined mass of low signal intensity, rather than of high signal intensity with a lobular configuration as typically seen in chondroma with hyaline cartilage. Knowledge of this type of mineralization may help in the diagnosis of extraskeletal chondroma.

Paradoxical motion in spondylolisthesis due to two-segment instability

We report here a paradoxical motion in unstable spondylolytic spondylolisthesis: a more forward displacement of the L5 vertebral body on the sacrum on the standing extension view than on the standing flexion view. An axial loading through the inferior articular process of the posteriorly displaced L4 on extension appears to be the cause, while the instability in the two contiguous segments may be an important contributing factor.

Relationship of elongated anterior tubercle to incomplete segmentation in the cervical spine

PURPOSE

To describe the elongated anterior tubercle of cervical vertebrae, its association with incomplete segmentation, and its analogy to sacralization of the lower lumbar vertebrae.

MATERIALS AND METHODS

Cases with elongated anterior tubercles of the cervical vertebrae detected on plain radiography were collected during routine practice and their features analyzed on plain radiography and MR imaging. Five patients, aged 19-40 years, with the anomaly seen on plain radiography were included in this study. MR imaging was undertaken in one patient.

RESULTS

Hypertrophy of the anterior tubercle was associated with incomplete segmentation in three of the five patients. Oblique views were adequate to demonstrate its nature.

CONCLUSIONS

The association of an elongated tubercle and incomplete segmentation is similar to partial sacralization at the lumbosacral junction. Clinically it is important that these anomalies are not mistaken for pathologic findings.

Cortical defect of the distal fibula: variant of ossification

PURPOSE

To elucidate the nature of a normally occurring cortical defect of the distal fibula.

MATERIALS AND METHODS

In patients with sprain and nonspecific ankle pain during a 2-year period, the authors reviewed ankle radiographs, computed tomographic (CT) scans, and magnetic resonance (MR) images. Cases were added from our file. Dried skeletons and cadavers were evaluated with radiography for the presence of this cortical defect.

RESULTS

Fifteen (1.8%) of 847 radiographs in 739 patients (male, 377; female, 362; age range, 15-84 years) showed a small cortical defect in the anterior aspect at the level of the distal tibiofibular joint. The age range of the subjects with the defect (male, four; female, 11) was 16-66 years. MR imaging in two patients showed a small low-signal-intensity area at the insertion site of the anterior tibiofibular ligament. Evaluation of 148 skeletons (75 subjects) revealed similar cortical defect in two cases (1.4%).

CONCLUSION

The cortical defect of the distal fibula, at the insertion site of the anterior tibiofibular ligament, has no clinical significance and should not be confused with neoplasm.

Desmoplastic fibroma. Aggressive curettage as a surgical alternative for treatment

In this article, the authors present 5 patients with desmoplastic fibroma and review the literature. Four patients had aggressive curettage with bone graft, and 1 had aggressive curettage alone. Although the literature reports that many patients have recurrence after curettage, there have been no recurrences in these 5 patients during followup periods ranging from 5 years 6 months to 9 years. Although wide excision has been recommended in the literature, treatment with aggressive curettage achieved clinical and radiographic control of the lesions for at least an intermediate duration of followup.

Muscular sarcoidosis

A 57-year-old woman with sarcoid nodules in muscles of the lower leg was reported. A star-shaped low signal intensity in the lesion on MR imaging, supposedly corresponding to fibrous scar, appears characteristic of this condition, although its specificity is still uncertain.

Simultaneous avulsion of patellar apexes bilaterally in a hemodialysis patient

A case of simultaneous bilateral avulsion of the patellar apexes is reported. Plain radiography showed bilateral patella alta, but MR imaging was diagnostic. Weakness of the tendo-osseous junction due to secondary hyperparathyroidism and additional chronic inflammatory changes due to repeated microtrauma were considered to be the cause of the rupture.

MR anatomy of the substantia innominata and findings in Alzheimer disease: a preliminary report

PURPOSE

To demonstrate normal MR anatomy of the substantia innominata and its changes in Alzheimer disease on MR imaging.

METHODS

Using a 1.5-T superconductive MR unit, thickness of the substantia innominata was measured on coronal thin-section images obtained in 22 patients with Alzheimer disease and 14 age-matched control subjects. Comparison of these images with postmortem specimens of human brain was also performed.

RESULTS

On T2-weighted images through the anterior commissure, the substantia innominata was clearly identified between the globus pallidus and the anterior perforated substance. In Alzheimer disease, thinning of the substantia innominata was more frequently observed than in the age-matched controls.

CONCLUSION

Thin-section T2-weighted coronal MR images can demonstrate shrinkage of the substantia innominata, a finding that may aid in the diagnosis of Alzheimer disease.

Atypical lipomas, liposarcomas, and other fat-containing sarcomas. CT analysis of fat element

The radiographic appearance of fat in and around soft tissue sarcomas was evaluated to assess the diagnostic potential of this finding. Based on the distribution of fat and other components, these tumors are classified into three types.

Magnetic resonance imaging of pseudomalignant osseous tumor of the hand

Noninfectious, nonneoplastic reactive processes of the hand, such as myositis ossificans circumscripta, pseudomalignant osseous tumor of soft tissue, and florid reactive periostitis, appear similar radiologically and histologically and are often difficult to differentiate. Magnetic resonance (MR) findings in two such lesions are reported. The extensive reactive change in the extraosseous soft tissue and the bone marrow and the relatively small extent of ossification may be characteristic. Although low-grade infection and small osseous neoplasms with reactive changes, such as osteoid osteoma, may still remain possible causes, MR imaging provides essential evidence for including noninfective, nonneoplastic reactive processes of uncertain cause in the list of differential diagnoses.

Case report 859: Massive calcium pyrophosphate dihydrate crystal deposition disease involving the wrist joint

A case of massive calcium pyrophosphate dihydrate crystal deposition disease (MCPDD) is reported. A 41-year-old Japanese man presented with swelling, intermittent pain, and limitation of motion in the wrist. Radiological studies indicated amorphous calcification and bone erosion. MCPDD, although rare, should be included in the list of the differential diagnosis of periarticular calcific diseases.

Fluid-fluid levels in cavernous hemangioma of soft tissue

Five cases of cavernous hemangioma with fluid-fluid levels on magnetic resonance imaging and/or computed tomography are reported. The signal characteristics were those of blood and histological analysis of the fluid-fluid levels showed that they were blood-filled cavities in the tumor. Although this finding itself is not specific, it may help in confirming the diagnosis of cavernous hemangioma.

Case report 829: Intramuscular myxoid chondrosarcoma

A 61-year-old man presented with a 6-month history of a painless mass in the right buttock. Although the MR appearance of myxoid neoplasms is variable, a myxoid neoplasm was suspected on the basis of the MR study. Percutaneous needle biopsy results yielded a diagnosis of intramuscular myxoma. Myxoid chondrosarcoma, however, was diagnosed at the time of excisional biopsy. One should be wary of a diagnosis of intramuscular myxoma based solely on the results of percutaneous needle biopsy. In addition, myxoid chondrosarcoma of the soft tissues can have a variable appearance on T1-weighted imaging.

Familial occurrence of telangiectatic osteosarcoma: cousin cases

Familial occurrence of osteosarcoma is rare. We report cousin cases, an 11-year-old girl and an 8-year-old boy with telangiectatic osteosarcoma. The tumors occurred in the metaphysis of the distal tibia and the lamina of thoracic vertebra. The local behaviors appeared aggressive, but the clinical courses were relatively indolent in both cases. The histologic features were similar, showing anaplastic tumor cells producing osteoid and proliferation of blood cavities. Clustering of malignancies within a family suggests the presence of a genetic factor.

Hippocampal sulcus remnant: potential cause of change in signal intensity in the hippocampus

A small area of changed signal intensity in the hippocampus is often seen on magnetic resonance (MR) images of the brain in patients without specific clinical signs or symptoms. To ascertain its cause by means of histologic examination, this finding was evaluated retrospectively in 109 patients and correlated with findings in two human brain specimens. This area of change was typically round or curvilinear and 1-2 mm in diameter. Its location was between the hippocampus and dentate gyrus. The signal intensity was the same as that of cerebrospinal fluid (CSF) with all MR sequences used. The incidence of change in signal intensity was greater in elderly patients. Correlation with histologic findings showed that this area of change, a dilated perivascular space, was the residual cavity of the hippocampal sulcus. Whenever an area of CSF-like signal intensity has this shape and topographic features, the possibility of anatomic variation should be considered before the change in signal intensity is diagnosed as brain injury.

Vesicourethral function after surgery for uterine cancer: predictive value of postoperative maximum urethral closure pressure on residual urine

Using a urodynamic technique, vesicourethral function was evaluated in 30 patients who had undergone surgery for uterine cancer. In all 28 patients treated with radical hysterectomy, detrusor function was damaged irrespective of the use of the Cavitron ultrasonic surgical aspirator (CUSA), whereas, in 2 patients treated with semiradical hysterectomy, the function was preserved. Vesicourethral functions 3 weeks after the operation in all 28 patients treated with radical hysterectomy showed underactive detrusor function with low compliance. In 10 out of these 28 patients, postoperative maximum urethral closure pressure (MUCP) did not decrease, without relation to the use of CUSA nor to the presence of detrusor sphincter dyssynergia, and more than 5 weeks were required to reduce residual urine to less than 50 ml. On the other hand, in the remaining 18 patients, postoperative MUCP decreased, and residual urine decreased to less than 50 ml by 5 weeks after the operation. From the results obtained here, we can conclude that the evaluation of MUCP at an early phase after the operation is a useful tool to predict complications caused by residual urine, such as urinary tract infection, irreversible alteration of detrusor function or deterioration in renal function.

[Pseudodynamic MR imaging of temporomandibular joint disorders]

Magnetic resonance (MR) imaging of the temporomandibular joint (TMJ) has now been established as a procedure of choice in the evaluation of TMJ disorders. In this study, we evaluated the dynamics of TMJ motion on MR imaging, which resembles arthrography. Sixty-eight TMJs in 38 symptomatic patients and one healthy volunteer were examined using pseudodynamic images with gradient echo sequences using a 0.5 Tesla MR unit and 8 cm circular planar surface coil. For depiction of each compartment of the meniscus, the optimum sequence was 200/15/2 (TR/TE/excitations) with 50 degrees or 60 degrees flip angle in gradient refocused acquisition in steady-state (GRASS) sequences. Three contiguous slices on sagittal MR images were routinely obtained at 14-18 different phases of the opening cycle and displayed in closed-loop cine fashion. Internal derangement was observed in 57% of 68 joints. The most common type was anterior meniscal displacement without reduction. Sideway and rotational displacements, observed in 10% each, were noted on both sagittal multislice images and axial reference images. As a pseudodynamic MR technique, jaw movement specifically designed to check bite procedure to adjust splints is useful for detecting the exact time of meniscal redisplacement on the second click. After conservative therapy for arthrosis, pseudodynamic MR provided information on changes in the meniscus and condylar relationship. Pseudodynamic MR with multiple phases is suitable for evaluating subtle motion abnormality of the meniscus and for post-therapeutic monitoring.

[Fluid-fluid levels in bone and soft tissue tumors demonstrated by MR imaging]

Fluid-fluid levels in bone tumors have been described in aneurysmal bone cysts and other cystic tumors of bones and soft tissue tumors. We experienced three bone tumors (simple bone cyst, bone metastasis, and osteosarcoma) and three soft tissue tumors (fibrosarcoma, two cases of cavernous hemangioma) that showed fluid-fluid levels on MR, and investigated their cause. Causes included blood in the cystic spaces, hemorrhage in the tumor, the telangiectatic component of the osteosarcoma, and the cavernous component of the hemangioma. No specific diagnosis could be made based on the finding of fluid-fluid levels. We conclude that fluid-fluid levels on MR are rather nonspecific findings in bone and soft tissue tumors and that the diagnosis should be made on the basis of other radiological and clinical findings.

Ossified soft tissue recurrence of giant cell tumor of bone

We report 3 cases of soft tissue recurrence of giant cell tumor of bone. A peripheral rim of ossification in the soft tissue mass is pathognomonic of recurrence in the patients after resection of giant cell tumor.

Radiologic evaluation of dens fracture. Role of plain radiography and tomography

A retrospective study of 50 dens fractures was performed. In 47 of 50 cases (94%), plain radiographs disclosed the fracture. Initial cross-table lateral view alone showed the fracture in 43 cases. In the remaining four cases, routine plain films revealed the fracture: open-mouth view in three cases and lateral skull view in one case. In 3 of 50 cases (6%), plain films were negative, and fractures were seen only on tomography. Conventional circular tomography was performed in 26 cases; results were divided into 3 categories according to the significance of the findings: Category I, tomography confirmed plain radiographic findings, but added no further information; Category II, tomography detected additional findings or showed the extent of injury better than plain radiography; Category III, fracture was only seen by tomography. There were 19 cases in Category I, 4 in Category II, and 3 in Category III. Careful evaluation of plain radiographs remains the primary method for diagnosis of dens fractures. Tomography should be performed whenever plain radiographs or clinical symptoms are suspicious for dens fracture. In addition, tomography is useful to define the fracture level and pattern, which are important factors in the management of these injuries.