Nodular fasciitis

Overview
Nodular fasciitis, also known as Nodular pseudosarcomatous fasciits and Subcutaneous pseudosarcomatous fibromatosis, is a benign lesion most commonly found in the superficial fascia. It is most common in young persons on the upper extremities and trunk. Commonly mistaken for a sarcoma.

Etiology and clinical course
Similar to a dermatofibroma, it is believed to be a reparative process secondary to trauma, which is frequently not remembered. It evolves rapidly, but is usually less than 3 cm in diameter. There is an extremely low incidence of recurrence after resection.

Histology

 * Histologically vast array of patterns.
 * Short S-shaped fascicles, inflammation, accelerated mitotic index with normal mitoses.
 * Essentially spindle cell proliferation.
 * Stroma is rich in collagen and/or myxoid ground substance.