Guzkowe zapalenie powięzi

A rare soft tissue tumor characterized by a solitary mass-forming fibrous proliferation that usually occurs in the subcutaneous tissue, composed of uniform fibroblastic/myofibroblastic cells displaying a loose growth pattern. Upper extremities, trunk, and head and neck are most frequently affected. The lesion typically grows rapidly and almost always measures less than five centimeters in diameter. Macroscopically, it may appear circumscribed or infiltrative but is not encapsulated. Recurrence after excision is very rare, and metastasis does not occur.