It is composed of firm, irregular nodules varying in color from flesh to reddish-brown. Sometimes it may present as a morphea-like, atrophic, sclerotic, violaceous plaque without nodularity that may ulcerate as it slowly increases in size. DFSP is seen most commonly on the trunk, followed by the proximal extremities. It rarely occurs above the neck. Currently, the cause of DFSP is unknown.
Skin biopsy is essential for definite diagnosis.
No imaging studies are employed unless metastatic disease is suspected after thorough history taking and physical examination. In the plaque type of DFSP, slender tumor cells with large, spindle-shaped nuclei are embedded fairly uniformly in the collagen stroma, parallel to the skin surface. Mitotic figures are sparse. The more characteristic findings are seen in the nodular type. These include the high cellularity and irregular short intersecting bands of tumor cells forming a storiform pattern.