dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a rare neoplasm of the dermis layer of the skin, and is classified as a sarcoma. In many respects, the disease behaves as a benign tumor, but in 2-5% of cases it can metastasize, so it should be considered to have malignant potential. Over 95% of DFSP tumors have the chromosomal translocation t(17;22). The translocation fuses the collagen gene (COL1A1) with the platelet-derived growth factor gene. The fibroblast, the cell of origin of this tumor, expresses the fusion gene in the belief that it is collagen. However the resulting fusion protein is processed into mature platelet-derived growth factor which is a potent growth factor. Fibroblasts contain the receptor for this growth factor. Thus the cell "thinks" it is producing a structural protein, but in fact produces a self-stimulatory growth signal. The cell divides rapidly and a tumor forms.
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Dermatofibrosarcoma pro·tu·ber·ans n. A slow-growing dermal neoplasm consisting of one or more purplish nodules that tends to recur but usually does [more]Dermatofibrosarcoma protuberans - Community and Resources

[DER-ma-toe-FI-bro-sar-KO-ma pro-TOO-ber-anz]
A type of tumor that begins as a hard nodule and grows slowly. These tumors are usually found in the dermis (the inner layer of the two main layers of tissue that make up the skin) of the limbs or trunk of the body. They can grow into surrounding tissue but do not spread to other parts of the body. These tumors are related to giant cell fibroblastoma.