Proliferative fasciitis and proliferative myositis

A benign soft tissue lesion

Proliferative fasciitis and proliferative myositis are rare, benign soft tissue lesions that typically occur in adults. These conditions are characterized by rapid growth and can be mistaken for malignant tumors due to their aggressive appearance. However, they are non-cancerous and have a good prognosis after surgical excision.

Pathophysiology

Proliferative fasciitis and proliferative myositis are part of a group of pseudosarcomatous proliferations, which are reactive processes rather than true neoplasms. They are thought to arise from fibroblasts and myofibroblasts, which are cells involved in wound healing and tissue repair. The exact cause of these lesions is unknown, but they may be triggered by trauma or other local factors.

Clinical Presentation

These lesions typically present as rapidly enlarging masses in the soft tissues of the extremities, trunk, or head and neck region. Patients may notice a firm, painless swelling that grows over a period of weeks to months. Although the lesions can be alarming due to their rapid growth, they are usually not associated with systemic symptoms.

Histopathology

Histopathology of proliferative fasciitis or myositis

Histologically, proliferative fasciitis and proliferative myositis are characterized by a proliferation of spindle-shaped cells and giant cells within a myxoid stroma. The presence of ganglion-like cells is a distinctive feature. These cells are large, with abundant cytoplasm and vesicular nuclei. The lesions are well-circumscribed and lack the atypical mitotic figures seen in malignant tumors.

Diagnosis

The diagnosis of proliferative fasciitis and proliferative myositis is primarily based on histological examination. Imaging studies such as MRI or CT scan may be used to assess the extent of the lesion and its relationship to surrounding structures. A biopsy is often necessary to differentiate these lesions from malignant soft tissue tumors.

Treatment

The treatment of choice for proliferative fasciitis and proliferative myositis is surgical excision. Complete removal of the lesion usually results in a cure, and recurrence is rare. In some cases, observation may be appropriate if the lesion is asymptomatic and not causing functional impairment.

Prognosis

The prognosis for patients with proliferative fasciitis and proliferative myositis is excellent. These lesions are benign and do not metastasize. Following surgical excision, patients typically have no further issues related to the lesion.

Related pages

• Soft tissue tumor
• Fibroblast
• Myofibroblast
• Pseudosarcomatous proliferation