Dermatofibrosarcoma protuberans (dermatofibrosarcoma protuberans) - Fusion of the COL1A1 and PDGFB genes.

Dermatofibrosarcoma protuberans is a rare type of cancer that causes a tumor in the deep layers of the skin. This alteration is a type of soft tissue sarcoma. Often, the tumor starts as a patch of skin firm, usually from 1 to 5 centimeters in diameter, usually purple, red or reddish. Generally, the tumor grows slowly and can become a large nodule. Often, the tumor starts as a flat spot or depressed skin. Tumors are most often in the back, but can also be found on the arms, legs, head or neck. Usually, people affected show early signs around thirty years, but the age at which a tumor appears varies widely. Although rarely metastasize, this type of tumor tends to recur once removed.

Variants described dermatofibrosarcoma protuberans in which are involved in tumor cell types. A variant, the Bednar tumors, often called pigmented DFSP contain dendritic cells containing melanin. A second variant, myxoid DFSP tumors contain an abnormal type of connective tissue known as myxoid stroma. A third variant, fibroblastoma giant cells, also known as juvenile dermatofibrosarcoma protuberans, sometimes characterized by giant cells in the tumor. Rarely, tumors involved in different types of DFSP may have regions that resemble fibrosarcoma, a more aggressive type of soft tissue sarcoma. In these cases, the condition is called fibrosarcomatous DFSP or FS-DFSP. The FS-DFSP tumors are more prone to metastasis than in other types of protuberant dermatofibrosarcoma.

Dermatofibrosarcoma protuberans is associated with translocation of genetic material between chromosomes 17 and 22. This translocation, t (17; 22), fuses of the COL1A1 gene on chromosome 17 with part of PDGFB gene on chromosome 22. The translocation in one or more additional chromosomes that can be either normal linear or circular form. When circular, extra chromosomes are known as supernumerary chromosomes ring. Other genes of chromosomes 17 and 22 are in the extra chromosomes, but the role these genes play in the development of the disease is unclear. Translocation is acquired during the life of a person and chromosomes containing the translocation are present only in tumor cells. This type of genetic change called a somatic mutation.

In normal cells, the COL1A1 gene, located on the long arm of chromosome 17 (17q21.33), encoding part of type I collagen, which strengthens and supports many tissues in the body. The PDGFB gene, located on the long arm of chromosome 22 (22q13.1), encodes a protein isoform of platelet-derived growth factor (PDGF). Binding to its receptor, the protein stimulates PDGFB many cellular processes, including growth, proliferation and cell differentiation. The COL1A1-PDGFB fusion leads to the coding of an excessive amount of protein that functions as the PDGFB protein. In excess, this fusion protein stimulates cells to proliferate and differentiate abnormally, resulting in the formation of characteristic tumors dermatofibrosarcoma protuberans. COL1A1 gene-PDGFB is in over 90% of cases of DFSP. In other cases, changes in other genes may be associated with this condition. However, these genes have not been identified.

Dermatofibrosarcoma protuberans is due to a new mutation that occurs in the body 's cells after conception and is found only in tumor cells. This type of genetic change called a somatic mutation and usually not inherited.

Tests in IVAMI: in IVAMI perform detection fusion COL1A1 gene and PDGFB gene associated with dermatofibrosarcoma protuberans by genomic amplification of potential fusion partners using as target 32 exons of the COL1A1 gene and exon 2 PDGFB gene followed by sequencing of the fusion product should be.

Samples recommended: When a somatic mutation, biopsy of tumor tissue or a biopsy cuts included in paraffin (about 40 cuts of 5 microns) is required.