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At least 19 recordsLinked to original sources

The subcutaneous fascial analogue of myositis proliferans: electron microscopic examination of two cases and comparison with myositis ossificans localisata.

Two cases of the so-called fascial analogue of myositis proliferans were investigated by histological and electron microscopic methods. It was found that the structure of the fascial variant corresponds almost completely to the true myositis proliferans localized within the musculature. The electron microscopic observations show a preponderantly histiocytic differentiation of the cells and strongly activated proliferating capillaries, and exclude a myogenic origin of the characteristic ganglion-like giant cells. Ultrastructurally a traumatic genesis appears possibly, the cells of the lesion could derive from multipotent cells of the microvasculature. The relations to myositis ossificans and fascitis nodularis are discussed.

Adult

Focal myositis of the perioral musculature.

Focal myositis, a benign inflammatory pseudotumor, is a relatively newly defined clinicopathologic entity which arises as a rapidly enlarging swelling within an isolated skeletal muscle. It occurs most often in the lower extremity, and we are reporting what we believe to be the first cases of perioral involvement. There is no apparent age or sex preference. Focal myositis must be differentiated from neoplasm, nodular pseudosarcomatous fascilitis, proliferative myositis, myositis ossificans, polymyositis, and, in the oral region, salivary gland lesions and hypertrophic branchial myopathy. No lesions have recurred.

Adult

[Difficulties in the differential diagnosis of a non-traumatic, active myositis ossificans during pregnancy (author's transl)].

A 28 year old patient complained of sensory disturbances and pain in the right upper arm during pregnancy. During the 32nd week of her pregnancy, a large painful mass developed in the flexor muscles which, radiographically, showed some calcification. A diagnosis of a parosseous sarcoma was made; biopsy, however, indicated a diagnosis of non-traumatic myositis ossificans. Since the histological appearances of active myositis may be vary difficult to distinguish from a juxtacortical sarcoma, a right brachial angiogram and scintiscan were obtained. The angiographic and scintigraphic findings were erroneously considered to suggest malignancy. Following delivery, the tumour was removed. Futher histology confirmed the diagnosis of localised, non-traumatic myositis ossificans. The value of radiology, biopsy, angiography and scintigraphy are discussed with reference to our experience.

Adult

Myositis ossificans: diagnostic value of arteriography.

Myositis ossificans circumscripta is the heterotopic formation of nonneoplastic bone and cartilage in soft tissue. These benign lesions can mimic more serious lesions, both radiographically and histopathologically. Recognition of the benign character of myositis ossificans is imperative in order to avoid mutilating surgical procedures. Five cases are presented with emphasis on angiographic signs which differentiate this lesion from histopathologically similar lesions. Three of these are illustrated, along with an example of an osteosarcoma for comparison. The angiographic manifestations of myositis ossificans differ in the various phases of the disease. In the active stage, the lesions have numerous fine vessels causing a diffus stain. Malignant tumors such as osteosarcoma, extraosseous osteosarcoma, and fibrosarcoma, which are included in the differential diagnosis, often present clearly defined pathologic vessels as well as arteriovenous shunts, venous lakes, amputated vessels, invasion of large arteries and veins, and large abnormal draining veins. In the healing stage, the lesions are usually avascular, and there is no difficulty in differentiating this condition from malignant bone lesions with the sole exception of well differentiated parosteal osteosarcomas. In these cases, the plain radiographic features are most important in arriving at the correct diagnosis.

Adolescent

Alternating proptosis. A case report of acute orbital myositis defined by the computerized tomographic scan.

A 27-year-old woman had a two-week course of acute painful right proptosis with ptosis, medial conjunctival injection, and restriction of eye movements--particularly abduction. One month later, a similar remitting painful left proptosis with complete limitation of abduction developed. Computerized tomographic x-ray scanning showed marked contrast enhancement of both medial rectus muscles, documenting the presumptive diagnosis of acute orbital myositis without recourse to invasive diagnostic techniques. Myositis is a common component of idiopathic orbital inflammatory disease (orbital pseudotumor), but awareness of the rare patient with acute inflammation clinically localized to the extraocular muscles will decrease confusion with cranial nerve and cavernous sinus disease.

Acute Disease

Primary suppurative myositis in children.

Primary suppurative myositis is rare in the United States when compared with the incidence of disease in the tropics. Clinically, it may mimic many of the more common diseases, such as hematoma, osteomyelitis, arthritis, or appendiceal abscess. It usually has a benign course, with complete recovery after appropriate treatment. Prolonged morbidity and an increased mortality may result from unfamiliarity with this entity. Six children had primary suppurative myositis; one died as a result of perforation of a psoas abscess into the dural sac causing staphylococcal meningitis.

Child

Gene Contribution of Streptococcus dysgalactiae Subspecies equisimilis, an Emerging Pathogen, to Experimental Primate Necrotizing Myositis.

Streptococcus dysgalactiae subspecies equisimilis (SDSE) is an emerging human pathogen closely related to group A Streptococcus. However, its genetic requirements for survival and growth in different conditions and for causing invasive infections remain poorly understood. To address this gap, transposon-directed insertion-site sequencing was used to identify genes contributing to fitness in experimental necrotizing myositis in nonhuman primates. Using two SDSE stG62647 human clinical isolates, MGCS36044 and MGCS36089, highly saturated transposon mutant libraries were generated and analyzed following in vitro growth and in vivo infection in eight nonhuman primates. A total of 398 essential genes were identified to be shared by both strains during growth in vitro and in vivo, and 17 and 7 conditionally essential genes required only in vitro or only in vivo, respectively. Additionally, 117 and 110 genes in MGCS36044 and MGCS36089, respectively, were found to be associated with fitness during necrotizing myositis. Transposon insertions in 34 MGCS36044 genes conferred increased fitness, whereas mutation of 83 genes conferred decreased fitness. Similarly, in MGCS36089, mutations in 38 and 72 genes conferred increased or decreased fitness, respectively. Importantly, both strains shared 46 fitness-associated genes, including an enrichment of transporter genes, highlighting nutrient acquisition as a dominant requirement during infection. The results provide critical information for guiding future translational efforts to develop preventive and therapeutic strategies against human SDSE infections.

Animals

Calcitonin for myositis ossificans.

A case of myositis ossificans, following a hemiparesis due to a cerebral haemorrhage and treated with synthetic slamon calcitonin, is described. An improvement in joint range and a cessation of further ectopic calcification was seen but, because of the remitting nature of myositis ossificans itself, the therapeutic role of calcitonin in this case is unproven.

Calcitonin

Effect of denervation on coxsackie A virus myositis in mice: an electronmicroscopic study.

Myositis induced by Coxsackie A4 and A9 viruses was investigated in the gastrocnemius muscles of suckling mice and adult mice with denervation. Denervation markedly increased the susceptibility of adult mice to Coxsackie A virus infection, and this effect was initiated as early as 1 day after denervation. Light microscopy demonstrated inflammation and necrosis in the denervated gastrocnemius muscle of adult mice, whereas muscle from the contralateral leg showed only infrequent, mild, focal myositis. Ultrastructually, crystalline arrays of virus particles were seen in the infected muscle fibers and in the phagocytes of both suckling and adult mice. Nuclear alterations, especially in the myotubes, and a characteristic compound membrane-vesicle complex (CMVC) in the sarcoplasm, developed simultaneously. Replicating and fusing myoblasts, activated as part of the regenerative process after denervation, appeared to be closely associated with the susceptibility of muscle to Coxsackie A virus infection.

Animals

[Granulomatous myositis during collagenosis (one case) and suprasellar dysgerminoma (one case) (author's transl)].

Two cases of mainly interstitial myositis with epitheloid and giant cells are reported. In the first case, the late amyotrophic-type paralysis of the two girdles, of the clinical myositis type, was associated with severe myocardial damage, the atrioventricular conduction disorder requiring a pace-maker. This observation would appear to be a true polymyositis of the collagen diseases, in view of the associated skin affection, death occurring within a year, a large increase in serum muscle enzymes and urine creatine, the existence of a rheumatoid factor and striated muscle antibodies, and a large increase in M and G immunoglobulins. In the 2nd case, the amyotrophic affection of the pelvic girdle was associated with progressive blindness, diabetes insipidus, and anterior pituitary insufficiency. Death occurred after two years and autopsy showed a suprasellar dysgerminoma (ectopic pinealoma) without any visceral localization of sarcoidosis. The authors discuss the concept of granulomatous polymyositis, autonomous with respect to the sarcoidosis, and sometimes symptomatic of an inflammatory connective tissue condition or a malignant tumor.

Blindness

Nodular fasciitis and proliferative myositis as variants of one disease entity.

The concept of nodular fasciitis and proliferative myositis as variants of the same fibroblastic disorder is supported by intermediary cases, showing simultaneous features thought to be typical of either nodular fasciitis or proliferative myositis. Various other anatomical, pathological and clinical similarities found in this study of 100 cases support such conclusions. 'Ganglion-like' cells were a distinct, but not exclusive, feature of all cases with sole, or only partial, muscle involvement.

Adult

Ultrasound appearance of myositis ossificans.

Ultrasonic evaluation of a soft tissue mass of the thigh was performed and suggested the diagnosis of myositis ossificans. Correlation with routine radiographic studies is made, as well as with the follow-up radiographic examination.

Adult

Ultrastructural evidence of myofibroblasts in pseudomalignant myositis ossificans.

Seven cases of pseudomalignant ossifying myositis with a typical clinical symptomatology have been reported. None of the cases had experienced an injury. All the lesions were intramuscular and all of them showed a zonal arrangement. Electron microscopy in three cases allowed the demonstration of cells showing morphological features of myofibroblasts and monocytic cells of the macrophage type. These previously unreported features together with the zonal pattern of the lesions indicate their reparative nature.

Adolescent

Focal myositis of the neck.

Focal myositis is a recently defined, rapidly growing, inflammatory pseudotumor of skeletal muscle. It is characterized by marked myopathic changes of muscle fibers, hypocellular fibrosis of perimysium and endomysium, and an intense inflammatory reaction in the fibrous septa. This report describes the first instance involving the neck muscle of a 40 year old man. A brief discussion of other histologically similar subcutaneous lesions is also presented.

Adolescent

[Non-traumatic myositis ossificans circumscripta (author's transl)].

The clinical, pathological and radiological features and the differential diagnosis of the very rare condition of non-traumatic myositis ossificans circumscripta are illustrated by one patient. The characteristic radiological appearances make a correct diagnosis of this localised, non-malignant process possible.

Adolescent

Tropical myositis: ultrastructural studies.

Specimens of muscle were obtained from non-suppurating lesions of nine patients with tropical myositis. When examined in an electron microscope, these revealed patchy myocytolysis with loss of band structure. Perimysial cells were also degenerate. Sections from two out of nine patients revealed intracellular vesicles, about 80 nm in diameter, some of which contained 10 nm granules. These vesicles were seen budding from cell membranes and resembled virus particles. The focal necrosis with which they are associated and their absence from control sections support the concept that they are related to the disease process.

Cell Membrane