Epidemiology
A benign fibroblastic lesion of adults that arises within muscle and can grow quickly. Rapid growth within the muscle must be taken seriously, but pathologic confirmation avoids treating a reactive lesion as a sarcoma.
Basic features
Its speed of appearance can mimic a sarcoma, but pathology shows a characteristic reactive pattern.
Usual treatment
It is confirmed with a biopsy when the presentation is concerning; it can then be observed or removed if it remains symptomatic.
Outcomes and prognosis
Many lesions stabilize or resolve, and recurrence is rare when the diagnosis is correct.