Recent advancements in cancer genetics and molecular biology methods have elucidated the COL1A1-PDGFB fusion gene, some novel fusion gene variants and pathways related to DFSP pathogenesis that have resulted in the evolution of cutaneous sarcoma diagnosis and treatment.
Dermatofibrosarcoma protuberans is underlined by recurrent collagen type I alpha 1 chain-platelet-derived growth factor B chain (COL1A1-PDGFB) fusions but ~ 4% of typical dermatofibrosarcoma protuberans remain negative for this translocation in routine molecular screening.
The high frequency of PDGFB rearrangement in vulvar DFSP provides a useful exploit in diagnostically challenging cases and genetic evidence of probable clinical response to targeted therapeutics in cases of locally advanced or metastatic tumors.
Hyalinized zones with cracking artifact, mimicking giant cell fibroblastoma, were present in a 44 (30%) of cases; however FISH for PDGFB gene rearrangement was negative in five tested cases.
This is one of the few studies to demonstrate the value of FISH analysis of the COL1A1-PDGFB gene, which could validate complicated and suspected diagnoses in the routine biopsy of DFSP.
Dermatofibrosarcoma protuberans is characterized by a specific translocation t(17;22)(q22;q13) leading to the formation of COL1A1-PDGFB fusion transcripts.
With the development of cytogenetic and molecular biology techniques, the detection of fusion transcripts of the collagen type 1a1 (COL1A1) and platelet-derived growth factor-BB (PDGFB) genes has been recognized as a reliable and valuable molecular tool for the diagnosis of DFSPs.
Dermatofibrosarcoma protuberans (DFSP) is an aggressive PDGFB-dependent cutaneous sarcoma characterized by infiltrative growth and frequent local recurrences.
Although COL1A1/PDGFB fusion gene was identified in the tumor cells recently, not all of the cases were positive for the fusion gene, and further researches are still needed to clarify the pathogenesis of DFSP.
Molecular characterisation showed the absence of COL1A1-PDGFB fusion transcripts in cases 1, 3 and 4, excluded diagnosis of giant cell fibroblastoma in all cases.
The most remarkable cytogenetic feature of DFSP is the chromosomal translocation t(17;22)(q22;q13), causing a fusion of the platelet-derived growth factor beta chain (PDGFB) gene at 22q13, and the collagen type 1 alpha 1 (COL1A1) at 17q22.
The COL1A1-PDGFB fusion protein activates the PDGFB receptor and resultant constitutive activation of PDGFR receptor is essential in the pathogenesis of DFSP.
Differentiating dermatofibrosarcoma protuberans (DFSP) from other dermatofibromas using CD34 immunohistochemistry alone is difficult; therefore, fluorescence in situ hybridisation (FISH) analysis is often employed to identify typical COL1A1-PDGFB fusion or gene rearrangement.
FISH analysis revealed COL1A1-PDGFB gene rearrangement in all DFSP cases (n=7), whereas RT-PCR could detect the COL1A1-PDGFB fusion transcript only in 1 DFSP.Two cases were negative.
Genetic aberrations involving the platelet-derived growth factor-beta (PDGFB) gene and the collagen type 1 alpha1 (COL1A1) gene have been implicated in the pathogenesis of dermatofibrosarcoma protuberans (DFSP), a slow-growing and locally infiltrative dermal tumour.