Extent and level of fascial involvement in 100 cases with nodular fasciitis.

Nodular fasciitis (NF) shows a cellular proliferation which leads to widening of the fascia. Frequently unilateral or more often bilateral disruption of the fascia, with an infiltrative pattern is present. Subcutaneous fascia and surrounding fat are involved. Superficially the cellular proliferation may extend into dermal connective tissue. Deeper muscular tissue may be involved, with transitional forms or purely intramuscular changes, compatible with proliferative myositis. Proliferative myositis is considered to be a deep-seated variant of NF with muscular involvement. Intramuscular myxoma may be thought of as an intramuscular and mucoid variant of NF. A bilateral infiltrative pattern was most frequently found at all levels; in cases with muscular involvement it was always present.