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.
Molecular biology has been valuable in showing dermatofibrosarcoma protuberans and infantile fibrosarcoma that are characterized by COL1A1-PDGFB and ETV6-NTRK3 rearrangements respectively.
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.
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.
Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive malignant fibroblastic/myofibroblastic tumor of the skin, characterized by the t(17:22)(q22:q13) translocation resulting in fusion of the COL1A1 and PDGFB genes.
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.
Cytogenetically, most dermatofibrosarcoma protuberans are characterized by chromosomal rearrangements resulting in the collagen type-1 alpha 1 (COL1A1)-platelet-derived growth factor β (PDGFB) fusion gene.
The COL1A1-PDGFB fusion protein activates the PDGFB receptor and resultant constitutive activation of PDGFR receptor is essential in the pathogenesis of DFSP.
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.
DFSP is thought to result from a translocation between platelet-derived growth factor beta (PDGFB, 22q13.1) and type 1 collagen (COL1A1, 17q21≈22) leading to a fusion protein (PDGFB) which stimulates the PDGF receptor.
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.
The characteristic DFSP-associated translocation, t(17;22)(q22;q13), was identified in 6 patients; results of fluorescence in situ hybridization were positive for fusion of the COL1A1 and PDGFB loci in 7 patients; and RT-PCR showed the COL1A1-PDGFB fusion transcript in 6 patients.
Identification of t(17;22)(q22;q13) (COL1A1/PDGFB) in dermatofibrosarcoma protuberans by fluorescence in situ hybridization in paraffin-embedded tissue microarrays.
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.
To analyse the presence of collagen type I alpha 1-platelet-derived growth factor beta (COL1A1-PDGFB) transcripts in 20 cases of dermatofibrosarcoma protuberans (DFSP) and to assess the relationship between COL1A1 breakpoints and clinical and histopathological variables.