Cases of the day. Pediatric. Myositis ossificans circumscripta

Diagnostic utility of perilesional muscle edema in myositis ossificans

OBJECTIVES

To investigate the value of extensive perilesional muscle edema for the differentiation between myositis ossificans (MO) and malignant intramuscular soft tissue tumors on MRI.

MATERIALS AND METHODS

Two blinded readers analyzed MR examinations of 90 consecutive patients with intramuscular soft tissue masses (group 1: MO, n = 20; group 2: malignant tumors, n = 70). Extent of edema around lesions was graded (0, none; 1, minimal edema; 2, moderate edema; 3, extensive edema). Edema-lesion ratio (ELR = ratio of the maximal diameter of the edema and the maximal diameter of the central lesion) was calculated. ROC analysis, Mann-Whitney U test, and Kappa test were used.

RESULTS

A total of 70% and 60% of patients with MO had edema grade 3 (reader 1/reader 2), 30%/40% edema grade 2. For the patients with malignant tumors, it was 2.9%/1.4% (edema grade 3) and 16%/23% (edema grade 2). Interrater reliability was substantial (kappa = 0.66). Extent of edema was significantly higher for patients of group 1 (p < 0.0001, both readers). Mean ELR was 3.60 (group 1) and 1.35 (group 2), with statistically significant differences (p < 0.0001). Grade 3 edema showed a sensitivity/specificity of 70%/97.1% (reader 1) and 60%/99% (reader 2) for diagnosing MO. For ELR > 2.0, sensitivity was 90% and specificity 91% for diagnosing MO.

CONCLUSIONS

Extensive perilesional muscle edema on MRI of more than double the size of the central lesion is highly specific, but not pathognomonic for myositis ossificans in the early/intermediate stage in the differentiation to malignant intramuscular soft tissue lesions.

Nontraumatic Myositis Ossificans as an Uncommon Cause of Scoliosis: Case Report and Review of the Literature

BACKGROUND

A 5-year-old pediatric patient developed scoliosis associated with nontraumatic myositis ossificans in the lumbar region. Although there have been reports in literature of syndromes leading to widespread muscle ossifications resulting in shoulder deformities owing to impaired movement in the facet joints, to the best of our knowledge there has been no report of scoliosis associated with myositis ossificans.

CASE DESCRIPTION

The case presented is of a 5-year-old girl who developed scoliosis associated with nontraumatic myositis ossificans in the lumbar region. On the thoracolumbar radiograph, a hyperintense lesion was seen at the right-side L2-L3 level and scoliosis with a Cobb angle of 16.2° to the right side. The decision for surgery was made with the consideration of the existing scoliosis and that the complaints were associated with paravertebral calcified lesions adjacent to the facet joints. After surgery, the scoliosis improved.

CONCLUSIONS

Nontraumatic, paravertebral myositis ossificans at an early age is a very rare pathology. Therefore, it must be recognized that spine deformities such as scoliosis and kyphosis can develop in neglected cases of paravertebral myositis ossificans. In addition, there is a high risk of confusion with malignant pathologies, such as osteosarcoma, in this area. Removal of the mass eliminates both the pain of myositis ossificans and prevents the development of scoliosis.

Myositis ossificans of the platysma mimicking a malignancy: a case report with review of the literature

The two main forms of myositis ossificans are congenital and acquired. Either form is rare in the head and neck region. The acquired form is often due to trauma, with bullying as a fairly common cause. This report of myositis ossificans of the platysma in an 11-year-old female patient emphasizes the need for a high index of suspicion in unexplainable facial swellings in children and the benefit of modern investigative modalities in their management.

Computed tomography in the diagnosis of myositis ossificans - case report

Background

The term myositis ossificans refers to the formation of ossifications in the muscles, ligaments and fascias, usually as a result of trauma. Fibrodysplasia ossificans progressiva is a rare genetic disease in which heterotopic ossifications appear in early childhood and are accompanied by feet and spine defects.

Case Report

We present a case of a 31-year-old woman with massive heterotopic ossifications who suffered multiple injuries. We would like to emphasize the role of computed tomography in the exact localization of ossifications.

Conclusions

Thanks to the volume rendering techniques and 3D image reconstructions, it is possible to precisely determine the position of ossifications in relation to the internal organs and blood vessels, allowing to schedule the surgery to remove the lesions.

Myositis ossificans mimicking sarcoma, the importance of diagnostic imaging - case report

Background

Myositis ossificans is localized inflammatory process affecting skeletal muscles. Very rarely it can affect one of the neck muscles and present as a neck tumor, it can be misdiagnosed as the clinical, radiological and histological examinations can mimic a sarcoma.

Case Report

We report a 29 year old female patient with neck tumor suspected to be a sarcoma who underwent full diagnostics imaging and open bipsy with histopatological examination, afterwards surgical excision was performed.

Conclusions

The aim of this study was to present the differential diagnosis based on diagnostics imaging between MO and malignant tumors, such as parosteal sarcoma, synovial sarcoma and malignant fibrous histiocytoma.

Precervical myositis ossificans in an infant secondary to child abuse

We present a 10-week-old girl with myositis ossificans circumscripta (MO) of the neck secondary to nonaccidental trauma. This condition is rarely seen in infants; furthermore, the majority of MO lesions develop in the extremities rather than the head and neck region. We will detail the US-guided biopsy technique used in our case, in addition to discussing the characteristic imaging and pathological findings of MO to assist in the diagnosis and successful treatment of this condition.

Myositis ossificans circumscripta: a paediatric case and review of the literature

Myositis ossificans circumscripta (MOC), characterised by non-neoplastic heterotopic bone formation in soft tissue and skeletal muscle, is rare in children. At onset, it is difficult to distinguish MOC from a musculoskeletal infection or neoplasm, particularly in absence of trauma, and a biopsy is frequently required. We describe an 11-year-old boy with MOC in his thigh. At admission, minor local trauma was referred, and clinical examination revealed a tender and painful mass in the left thigh. Hypothesising a periarticular infection, a wide-spectrum antibiotic and an anti-inflammatory drug were given. The magnetic resonance imaging revealed an enlarged mass with marked enhancement of the lesion and a central, irregular non-enhanced area due to necrosis. After incisional biopsy, the histopathological examination found immature osteoblasts inside striated muscle fibres, as well as proliferating fibroblasts, which are all compatible with MOC, thereby ruling out infection or malignancy. The CT scan showed calcified deposits arranged in a ring, thus confirming MOC; a radiological follow-up was suggested to detect the lesion's maturation. Three months after diagnosis, surgical excision was performed. The post-operative period was uneventful. Six months later, the child was in good condition, with no signs of recurrence. In the literature, 57 paediatric cases have been described; most of these had an acute course, required excision and then had a favourable evolution. Our case study confirms the good prognosis of MOC and underlines how this benign condition should be considered in children presenting a tender and painful soft-tissue swelling.

La myosite ossifiante circonscrite: à propos d’un cas

Myositis ossificans circumscripta is a benign lesion characterized by focal heterotopic soft tissue ossification, occurring in young people generally after localized trauma. Clinical and radiological appearances may mimic a sarcomatous neoplastic process. We report a case of myositis ossificans occurring after trauma, so as to illustrate the different imaging features of this benign pathology on conventional radiographs and computed tomography.

MR imaging of myositis ossificans: variable patterns at different stages

Five patients with a palpable mass at presentation underwent magnetic resonance (MR) imaging. The final diagnosis was myositis ossificans (MO). MR imaging features, particularly after injection of gadopentetate dimeglumine, mimicked those of an inflammatory mass or neoplasm. The lesions were excised in three patients, and the images were correlated with histologic findings. Three different appearances were noted on MR images, corresponding to the stages of maturation of MO. Two cases involved early-stage lesions, and T1-weighted MR images showed a mass with homogeneous intermediate signal intensity. Both lesions showed rim enhancement after contrast agent injection and high signal intensity on T2-weighted images. Pathologic specimens demonstrated stroma with masses of spindle cells in which osteoid production was interspersed. The enhanced rim of the lesion mimicked the expected MR appearance of an abscess or necrotic tumor. Areas of enhancement in adjacent muscle were also seen on postcontrast T1-weighted images. Intermediate-stage MO was present in one case; there was evidence of a thin rim of calcification on plain radiographs and fatty changes in the lesion on T1-weighted images, corresponding with histologic findings. One case of a mature lesion showed a considerable degree of peripheral calcification both on MR images and at histology. MR imaging is nonspecific in the diagnosis of early-stage MO.

MR imaging of edema accompanying benign and malignant bone tumors

To evaluate the incidence, quantity, and presentation of intra- and extraosseous edema accompanying benign and malignant primary bone lesions, the magnetic resonance (MR) studies of 63 consecutive patients with histologically proven primary bone tumors were reviewed. MR scans were assessed for the presence and quantity of marrow and soft tissue edema and correlated with peroperative findings, resected specimens and follow-up data. The signal intensity and enhancement of tumor and edema prior to and after intravenous administration (if any) of gadolinium-labeled diethylene triamine pentaacetate (Gd-DTPA) was analyzed. Marrow edema was encountered adjacent to 8 of 39 malignant tumors and 14 of 24 benign lesions. Soft tissue edema was found accompanying 28 of 39 malignancies and 10 of 24 benign disorders. On unenhanced T1-weighted MR images tumor and edema were difficult to differentiate. Tumor inhomogeneity made this differentiation easier on T2-weighted sequences. In 36 patients the contrast medium Gd-DTPA was used. Edema was present in 27 of these patients and the respective enhancement of tumor and edema could be compared. Edema always enhanced homogeneously, and in most cases it enhanced to a similar degree as or more than tumor. Marrow and, more specifically, soft tissue edema is a frequent finding adjacent to primary bone tumors. The mere presence and quantity of marrow and soft tissue edema are unreliable indicators of the biologic potential of a lesion. Unenhanced MR scans cannot always differentiate between tumor and edema, but the administration of Gd-DTPA is of assistance in differentiating tumor from edema.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnetic resonance imaging of myositis ossificans: analysis of seven cases

Myositis ossificans typically presents as soft tissue swelling with progressive ossification on radiographs. Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images. We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass.