Focal myositis presenting as pseudothrombophlebitis of the arm

Focal myositis: New insights on diagnosis and pathology

OBJECTIVE

To better define in a cohort study the clinical and pathologic features of focal myositis (FM).

METHODS

With the use of the usual clinicopathologic definition, each confirmed case of FM in the Lyon University Hospital's myopathologic database between 2000 and 2016 was retrieved. Clinical, pathologic, imaging, serologic, and therapeutic data were collected. When data were missing but feasible, appropriate pathologic analyses were performed.

RESULTS

Of the 924 patients included in the database, 37 (4%) had confirmed FM (14 female, 23 male patients). The main symptoms were pain (n = 30, 81%), muscular mass (n = 16, 43%), erythema at the site of FM (n = 12, 32%), and fever (n = 9, 24%). Serum creatine kinase was normal in most patients (81%); serum immune abnormalities were frequent (inflammatory syndrome in sera [39%], dysglobulinemia [52%], and anti-nuclear antibody positivity [29%]). In addition to confirming previously reported findings, pathologic analyses found significant rates of vasculitis (68%) and fasciitis (73%). Here, FM appeared frequently to be associated with other diseases such as immune-mediated inflammatory disease (IMID; 32%), neoplasia (24%), and radiculopathy (11%). Regarding outcomes, 64% of the cases had received immunosuppressive drugs, and the relapse rate was 41%.

CONCLUSION

The present study suggests that FM is not as innocuous as previously believed, particularly considering the associated disorders. Notably, patients with FM should receive careful IMID and neoplasia screening.

[Focal myositis: An unknown disease]

Focal myositis are inflammatory muscle diseases of unknown origin. At the opposite from the other idiopathic inflammatory myopathies, they are restricted to a single muscle or to a muscle group. They are not associated with extramuscular manifestations, and they have a good prognosis without any treatment. They are characterized by a localized swelling affecting mostly lower limbs. The pseudo-tumor can be painful, but is not associated with a muscle weakness. Creatine kinase level is normal. Muscle MRI shows an inflammation restricted to a muscle or a muscle group. Muscle biopsy and pathological analysis remain necessary for the diagnosis, showing inflammatory infiltrates composed by macrophages and lymphocytes without any specific distribution within the muscle. Focal overexpression of HLA-1 by the muscle fibers is frequently observed. The muscle biopsy permits to rule out differential diagnosis such a malignancy (sarcoma). Spontaneous remission occurs within weeks or months after the first symptoms, relapse is unusual.

Recurrent Focal Myositis in Childhood: A Case Report and Systematic Review of the Literature

BACKGROUND

Recurrent focal myositis in adulthood has been documented in case reports and case series. Existing textbooks and reviews do not mention or mention only in passing this entity in childhood. We present a patient with recurrent focal myositis and summarize available clinical, laboratory, management, and outcome data on this entity in the pediatric ages.

METHOD

We describe a nine-year-old patient with recurrent myositis of the left biceps. The terms "myositis" and "relapsing" or "recurrent" or "recurrence" were searched using the United States National Library of Medicine and the Excerpta Medica Database. Pertinent secondary references were also screened.

RESULTS

Another seven pediatric patients (five males and two females, median age ten years, interquartile range 7-14 years) with recurrent focal myositis were identified. In children, the calf was the most frequently involved muscle. Unlike adults, the myositis in children was usually painful. Episodes could be associated with normal or elevated erythrocyte sedimentation rate and blood levels of C-reactive protein, creatine kinase, and aspartate aminotransferase. Abnormalities of the creatine kinase value did not seem to be associated with a higher risk of recurrences.

CONCLUSIONS

Focal myositis has a favorable outcome in children. Recurrent focal myositis is rare and usually benign in childhood. More data are needed to improve the understanding of this condition.

Focal myositis: A review

Amongst the heterogeneous group of inflammatory myopathies, focal myositis stands as a rare and benign dysimmune disease. Although it can be associated with root and/or nerve lesions, traumatic muscle lesions and autoimmune diseases, its triggering factors remain poorly understood. Defined as an isolated inflammatory pseudotumour usually restricted to one skeletal muscle, clinical presentation of focal myositis is that of a rapidly growing solitary mass within a single muscle, usually in the lower limbs. Electromyography shows spontaneous activity associated with a myopathic pattern. MRI reveals a contrast enhanced enlarged muscle appearing hyper-intense on FAT-SAT T2 weighted images. Adjacent structures are spared and there are no calcifications. Serum creatine kinase (CK) levels are usually moderately augmented and biological markers of systemic inflammation are absent in most cases. Pathological histological features include marked variation in fibre size, inflammatory infiltrates mostly composed of T CD4+ lymphocytes and macrophages, degenerating/regenerating fibres and interstitial fibrosis. Differential diagnoses are numerous and include myositis of other origin with focal onset. Steroid treatment should be reserved for patients who present with major pain, nerve lesions, associated autoimmune disease, or elevated C reactive protein or CK.