Apparent diffusion coefficient map of a case of extramedullary plasmacytoma.

Plasmacytomas are rare tumors, which arise from the monoclonal proliferation of malignant plasma cells. They may affect either the bony skeleton or rarely the soft tissues, the latter being referred to as extramedullary or extraosseous. We report a case of an extramedullary plasmacytoma that presented as a soft tissue mass involving the muscles of the left leg, in a patient who was previously treated for multiple myeloma. We describe the MR Imaging characteristics of the tumor and highlight the usefulness of diffusion-weighted imaging with apparent diffusion coefficient mapping.

Heterologous Liposarcomatous Differentiation in Malignant Phyllodes Tumor is Histologically Similar but Immunohistochemically and Molecularly Distinct from Well-differentiated Liposarcoma of Soft Tissue.

Malignant phyllodes tumor (PT) infrequently displays heterologous differentiation, and when present is most often liposarcomatous. We identified five cases of malignant PT with regions identical to well-differentiated liposarcoma (WDLS) of soft tissue and evaluated them for MDM2 and CDK4 gene expression and amplification using immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), respectively. Despite indistinguishable morphology all cases of malignant PT with WDLS-like liposarcomatous differentiation were negative for MDM2 and CDK4 IHC and FISH, supporting different underlying pathogenesis.

Primary Pseudomyogenic Hemangioendothelioma of Bone.

Pseudomyogenic hemangioendothelioma (PMH) is a well-recognized neoplasm that usually arises in the soft tissue; concurrent bone involvement occurs in 24% of cases. PMH of bone without soft tissue involvement is rare. We describe the clinicopathologic findings of 10 such cases, the largest series reported to date. The study included 9 male and 1 female patient; their ages ranged from 12 to 74 years (mean 36.7 y). All patients had multiple tumors with a distinct regional distribution: 45% restricted to the lower extremity; 25% to the spine and pelvis; and 15% to the upper extremity. On imaging studies the tumors were well circumscribed and lytic. The neoplasms were composed of spindled cells arranged in intersecting fascicles with scattered epithelioid cells; epithelioid cells predominated in 3 cases. The neoplastic cells contained abundant densely eosinophilic cytoplasm and vesicular nuclei. There was limited cytologic atypia and necrosis, few mitoses (0 to 2/10 high-power fields), and inconspicuous stroma. Unique findings included abundant intratumoral reactive woven bone and hemorrhage with numerous osteoclast-like giant cells. Immunohistochemically, most tumors were positive for keratin, ERG, and CD31; CD34 was negative. The balanced t(7:19)(q22;13) translocation was documented in 3 cases. Follow-up is limited, but no patient developed documented visceral dissemination, and all have stable or progressive osseous disease. PMH exclusively involving bone is rare. It is multicentric, often involves the lower extremity, and has unusual morphology. The differential diagnosis includes epithelioid vascular neoplasms, giant cell tumor, bone forming neoplasms, and metastatic carcinoma. Because of its rarity, unusual presentation, and morphology, accurate diagnosis can be challenging.

Microdensitometric and microarchitectural alterations in irradiated mandibular fracture repair.

Head and neck cancer most often requires a multimodality approach to treatment that includes the use of radiotherapy. Unfortunately, radiation treatment can cause significant locoregional adverse effects with the particularly debilitating sequelae of late pathologic fracture. We aimed to define comprehensive metrics that will allow us to evaluate the efficacy of therapies aimed at assuaging the damaging effects of radiation on fracture healing.Six male rats (XRT/Fx) received a 36-Gy preoperative radiation dose delivered in 10 fractions over 10 days to their left hemimandible, whereas 6 other rats were not irradiated (Fx). After a recovery period, a unilateral osteotomy was performed with external distractor placement set to a 2.1-mm fracture gap on all the animals. Following a 28-day consolidation interval, mandibles were harvested and scanned via micro-computed tomography. Radiomorphometrics were extracted and analyzed with significance at P < 0.05.A quantifiable decrease in bone volume fraction (73.9% vs 78.6%; P < 0.05) was observed in XRT/Fx compared with Fx, without significant change in bone mineral density. Microarchitectural metrics were significantly altered in XRT/Fx compared with Fx, specifically trabecular thickness (0.37 vs 0.30 µm; P = 0.01), trabecular number (2.18 vs 2.45 N/mm; P = 0.04), and bone surface-bone volume ratio (5.50 vs 6.70; P = 0.01).We found that the irradiated and fractured bone demonstrated a significant diminution in bone quality and strength. We have established predictable and reliable radiographic measures that quantitatively demonstrate the degradative effects of radiation on fracture repair. We can now utilize these comprehensive metrics to evaluate the benefits of therapeutic interventions to remediate the damaging effects of radiation on fracture healing.

Nodular fasciitis: characteristic imaging features on sonography and magnetic resonance imaging.

OBJECTIVES: The purpose of this study was to evaluate the imaging features of nodular fasciitis on sonography and magnetic resonance imaging (MRI). METHODS: A retrospective search of the radiologic and pathologic databases over the past 10 years for the diagnosis of nodular fasciitis was performed. Sonographic and MRI features were described. Pathologic specimens were reviewed. RESULTS: Six pathologically confirmed cases of nodular fasciitis were found. The mean patient age was 19.5 years (range, 8-33 years); 3 patients were male and 3 were female. Four patients had sonography only; 1 patient had both sonography and MRI; and 1 patient had MRI only. Three masses were located in the subcutaneous tissue adjacent to fascia; 2 were at the subcutaneous/muscular border; and 1 was intramuscular; however, all were in contact with fascia and showed a fascial tail on sonography and MRI. On sonography and MRI, masses were oval with poorly defined lobulated borders, averaging 2.6 cm (range, 1.8-3.5 cm). On sonography, all masses were hypoechoic. On MRI, the masses were isointense to muscle on T1-weighted sequences, hyperintense to muscle on fluid-sensitive sequences, and enhanced avidly but heterogeneously. The masses were surrounded by fat. CONCLUSIONS: When a rapidly growing oval mass in contiguity with a fascial plane is recognized, the diagnosis of nodular fasciitis should be entertained. More importantly, the possibility of an inaccurate diagnosis by core biopsy exists, which may warrant gross resection.

Quantitative histomorphometric assessment of regenerate cellularity and bone quality in mandibular distraction osteogenesis after radiation therapy.

BACKGROUND: The use of mandibular distraction osteogenesis (MDO) for tissue replacement after oncologic resection in head and neck cancer could have immense therapeutic ramifications. We have previously demonstrated significantly decreased mechanical and microdensitomeric metrics of our MDO regenerate after 36-Gy radiation. Quantitative histomorphometry, a third metric, would permit objective investigation of the effects of radiation on tissue and cellular composition. Our hypothesis is that radiation-induced cellular depletion and diminution in function impair optimal bone regeneration. METHODS: Five rats received radiation to the left mandible; 5 received none. All animals underwent surgical placement of external fixators, creation of mandibular osteotomies, distraction to a 5.1-mm gap width, and consolidation. Point counting and color thresholding were performed. RESULTS: There was a significant increase in empty lacunae and a corresponding diminution in osteocytes after radiation. Whereas the volume fraction of mineralized, mature bone was not different, that of nonmineralized, immature osteoid was significantly increased in the radiated group compared with that in the nonradiated group. CONCLUSIONS: Our findings confirm our prior 2 metrics. Actually, all 3 diverse metrics--microdensitometry, biomechanical analysis, and histomorphometry--corroborate our hypothesis of cellular depletion and diminution of function as the potential mechanism of radiation-induced attenuation in the distracted regenerate. Furthermore, our findings of tissue and cellular changes in the irradiated regenerate elucidate the pathophysiology of decreased bone quality when amalgamated with our previous results. Therapeutic agents may now be introduced, and their effects on the irradiated regenerate critically measured, so that MDO may be used as a viable reconstructive option in patients with head and neck cancer.