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Query: UMLS:C0027121 (myositis)
 4,538 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Surface lesions of bone usually present little diagnostic dilemma because the majority are conventional osteochondromas. Other surface bone lesions include periosteal chondroma, periosteal chondrosarcoma, and parosteal osteosarcoma. Mineralized soft tissue lesions such as myositis ossificans, synovial chondroma, and synovial sarcoma may present in a similar fashion when they occur in a juxtaarticular position. The soft tissue osteochondroma or paraarticular osteochondroma may simulate some of these more aggressive tumors, and its recognition is important to avoid overtreatment. A case of an 11-year-old male with a soft tissue osteochondroma is reported to illustrate the characteristic radiographic and histological features of this rare entity. No prior reports have examined soft tissue osteochondroma for expression of parathyroid hormone related protein, an established cartilage tumor proliferative mitogen.
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PMID:Soft tissue osteochondroma: case report and immunohistochemistry for parathyroid hormone-related protein. 1684 64

Extraskeletal osteochondroma in the nape of the neck is rare and its pathological diagnosis is based on radiological and histopathological examination. It is vital that such a diagnosis be considered when a discrete, ossified mass is localised in soft tissues, even at atypical sites. Differential diagnoses include myositis ossificans, a lipomatous lesion, a pseudomalignant osseous tumour, an ossifying fibromyxoid tumour, an extraskeletal chondroma with endochondral ossification, synovial (osteo) chondromatosis, tumoural calcinosis, a synovial sarcoma, and an extraskeletal osteosarcoma. Clinical awareness of this benign entity is important as no malignant transformation or metastasis has been reported. Marginal excision with histopathological identification is the treatment of choice.
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PMID:Extraskeletal osteochondroma in the nape of the neck: a case report. 1691 87

An ossifying soft-tissue lesion is potentially malignant. The possibility of malignancy increases in the absence of significant trauma. Pseudomalignant myositis ossificans can be easily confused with malignant lesions. A 22-year-old man presented with an ossifying mass in the adductor compartment of the thigh. The mass was excised and histopathologically reported as a soft-tissue osteosarcoma, but was later confirmed as pseudomalignant myositis ossificans by a pathologist specialising in oncology. Careful consideration and correlation of clinical, radiological, and histopathological findings is required to ensure the correct diagnosis is made and both initial and ongoing management is appropriate.
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PMID:Pseudomalignant myositis ossificans mimicking osteosarcoma: a case report. 1720 May 48

The authors report an unusual case of myositis ossificans in the temporal muscle manifesting as grave opening limitation of the mouth and a hard firm mass in the right temporal fossa. CT scan examination revealed a bone density mass located in the region of the right temporal fossa, that fussed the right temporal bone with the right coronoid process and a joint-like image in the middle portion of this mass. Traumatic myositis ossificans is a pseudotumor-like benign disease most frequently found in extremities of young population. Cases in the craniofacial skeleton are rare. The masseter and sternocleidomastoid muscles are most commonly affected in this location. The clinicopathological features of scalp myositis ossificans may mimic other soft tissue tumors, requiring care for the differential diagnosis. Histologically, osteoblastic activity is sometimes observed, similar to an osteosarcoma. Then differential diagnosis between both entities must be established.
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PMID:Myositis ossificans of the temporalis muscle. Case report. 1766 12

A consecutive series of cases of dogs and cats with locked jaw syndrome (inability to open or close the mouth) are reported in this study. Dogs were significantly overrepresented (84.0%) and adult dogs were more frequently affected (81.0%). Temporomandibular joint ankylosis due to fracture was the most common cause (54.0%) of locked jaw syndrome. Additional potential causes of locked jaw syndrome are masticatory muscle myositis, neoplasia, trigeminal nerve paralysis and central neurological lesions, temporomandibular joint luxation and dysplasia, osteoarthritis, retrobulbar abscess, tetanus, and severe ear disease. Treatment of locked jaw is directed towards the primary cause. It is important to treat the tonic spasm in order to minimize periarticular fibrosis. Surgical intervention is recommended for temporomandibular joint ankylosis. Masticatory muscle myositis treatment is initiated by gradually opening the mouth, with medical treatment based on immunosuppressive therapy. Fracture and masticatory muscle myositis are associated with a relatively good prognosis in regard to short-term outcome as compared to animals with central neurologic lesions or osteosarcoma which have a poor prognosis.
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PMID:Locked jaw syndrome in dogs and cats: 37 cases (1998-2005). 1875 57

Fibro-osseous tumor of the digits is an uncommon, benign condition with an excellent prognosis after local excision. Like myositis ossificans, clinical and histological features may mimic a malignant tumour, especially an extraskeletal osteosarcoma. A correct interpretation of clinical, radiological and histological data is a prerequisite to avoid misdiagnosis and unnecessary radical surgery (for example, amputation). We report the case of a 15-year-old boy who presented with a slow-growing mass of the left thumb, which turned out to be a fibro-osseous tumor on microscopic examination. A complete excision was performed without loss of function. Fifteen months postoperatively, there was no local recurrence.
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PMID:[Fibro-osseous pseudotumor of the thumb. Report of a case]. 1923 2

Imaging and histology are two complementary morphological techniques which play a fundamental role in the diagnosis and management of soft tissue sarcomas. Imaging allows to identify some pseudosarcomatous benign lesions such as myositis ossificans, intramuscular hemangioma, angiomyolipoma, intramuscular lipoma, giant cell tumour of tendon sheath, desmoid tumour and elastofibroma. There is no formal criterion for diagnosing a sarcoma on magnetic resonance imaging (MRI) but malignancy is strongly suspected with the presence of necrosis and vascular, bone or joint invasion. Imaging may also suggest some histological types of sarcoma such as well-differentiated liposarcoma, dedifferentiated liposarcoma, synovial sarcoma or extraskeletal osteosarcoma. Imaging is also extremely helpful in determining the appropriate kind of sampling to carry out and in guiding the performance of a microbiopsy. The appearance observed on imaging should always be taken into consideration for the interpretation of the microbiopsy by the pathologist.
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PMID:Histology and imaging of soft tissue sarcomas. 1983 58

Parosteal osteosarcoma and low-grade central osteosarcoma are two types of low-grade osteosarcoma that show similar clinical behaviors, histological features, and genetic background (ie, amplified sequences of 12q13-15, including MDM2 and CDK4). Low-grade osteosarcoma is often confused with benign lesions, and ancillary techniques to enhance diagnostic accuracy have been awaited. This study explores the use of MDM2 and CDK4 immunohistochemistry for the histological diagnosis of low-grade osteosarcoma. We studied 23 cases of low-grade osteosarcoma from 21 patients (parosteal osteosarcoma (n=14), low-grade central osteosarcoma (n=9)) and 40 cases of benign histological mimics (myositis ossificans (n=11), fibrous dysplasia (n=14), osteochondroma (n=6), desmoplastic fibroma (n=1), florid reactive periostitis (n=4), Nora's lesion (n=3), and turret exostosis (n=1)). Low-grade osteosarcoma labeled for MDM2 in 16 cases (70%) and for CDK4 in 20 cases (87%). All low-grade osteosarcomas expressed one or both markers (100%), with 13 cases (57%) expressing both. Staining pattern was diffuse in most cases, and the majority expressed moderate or strong intensity for either antibody. MDM2/CDK4 immunostaining was shown irrespective of low-grade osteosarcoma histological subtype. In contrast, only 1 Nora's lesion out of the 40 miscellaneous benign processes showed immunoreactivity for MDM2 or CDK4. The combination of these two markers thus shows 100% sensitivity and 97.5% specificity for the diagnosis of low-grade osteosarcoma. MDM2 and CDK4 immunostains therefore reliably distinguish low-grade osteosarcoma from benign histological mimics, and their combination may serve as a useful adjunct in this difficult differential diagnosis.
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PMID:Immunohistochemical analysis of MDM2 and CDK4 distinguishes low-grade osteosarcoma from benign mimics. 2060 38

Mature bone formation in well-differentiated liposarcoma and dedifferentiated liposarcoma has been described as a reactive or "metaplastic" change in most reports, and its neoplastic nature has not been widely appreciated. We herein describe 9 cases of well-differentiated/dedifferentiated liposarcoma with distinct areas of fibroosseous tissue histologically indistinguishable from low-grade osteosarcomas, that is, parosteal osteosarcoma or low-grade central osteosarcoma. The tumors affected middle-aged to elderly patients, and occurred in the retroperitoneum and deep soft tissue of the extremities without connection to the skeletal system. Grossly, all the tumors showed biphasic appearance with lipogenic and osteogenic area, the latter representing 5% to 50% of the total tumor volume. Histologically, the lipogenic component exhibited typical histology of well-differentiated liposarcoma, whereas the osteogenic area consisted of fibroosseous tissue with numerous mature neoplastic bone trabeculae largely lacking osteoblastic rimming, with intervening fascicles of spindle cell proliferation showing low nuclear grade. All samples were positive for MDM2 and/or CDK4 on immunohistochemical analysis; the antibodies stained many osteocytes, indicating that the bone is neoplastic rather than reactive. Three cases showed high-grade osteosarcomatous transformation juxtaposed to the low-grade osteosarcomatous component, reminiscent of the "dedifferentiation" phenomenon of skeletal low-grade osteosarcoma. Follow-up revealed local recurrence in 4 cases, but no distant metastases were documented. Recognition of this earlier underappreciated subtype of well-differentiated/dedifferentiated liposarcoma is important, because the fibroosseous component may seem so bland that it may be confused with benign metaplasia such as myositis ossificans, or conversely, the lipomatous component may be inconspicuous that it may be dismissed as normal fat, and such misinterpretation may potentially result in suboptimal treatment.
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PMID:Well-differentiated liposarcoma with low-grade osteosarcomatous component: an underrecognized variant. 2069 54

Extraskeletal osteochondroma near the hip is rare and its pathological diagnosis is based on radiological and histopathological examination. It is vital that such a diagnosis be considered when a discrete, ossified mass is localized in soft tissues, even at atypical sites. Differential diagnoses include myositis ossificans, a lipomatous lesion, a pseudomalignant osseous tumour, an ossifying fibromyxoid tumour, an extraskeletal chondroma with endochondral ossification, synovial (osteo) chondromatosis, tumoural calcinosis, a synovial sarcoma and an extraskeletal osteosarcoma. Clinical awareness of this benign entity is important as no malignant transformation or metastasis has been reported. Marginal excision with histopathological identification is the treatment of choice.
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PMID:Extraskeletal osteochondroma near the hip: a pediatric case. 2080 44


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