title: Biphasic dermatofibrosarcoma protuberans with a labyrinthine plexiform high-grade fibrosarcomatous transformation.
abstract: Several variants of dermatofibrosarcoma protuberans, a low-grade superficial sarcoma, are well recognized. The most prognostically important is the fibrosarcomatous variant. We report a case of biphasic dermatofibrosarcoma protuberans in which the high-grade component exhibited a previously undescribed plexiform pattern. A clinicopathological study complemented with immunohistochemical, ultrastructural, reverse transcription polymerase chain reaction and fluorescence in situ hybridization analyses of this unique case. Histopathologically, a conventional low-grade dermatofibrosarcoma protuberans was admixed with intratumoral high-grade areas showing a striking labyrinthine plexiform pattern characterized by a higher cellularity of larger and slightly atypical tumor cells. CD34 expression was present in both components, while Ki-67 immunostaining was significantly higher in the plexiform high-grade areas. Focal epithelial membrane antigen and claudin-1 immunostaining was present at the interphase between high- and low-grade areas. COL1A1-PDGFB fusion transcripts, with breakpoints at exon 25 of COL1A1 and exon 2 of PDGFB, were present in both components, being more numerous, as the extra copies of both genes, in the high-grade areas. A previously undescribed histopathologic pattern of high-grade sarcomatous transformation of dermatofibrosarcoma protuberans is reported: a biphasic tumor with a labyrinthine plexiform high-grade component.
authors.affiliation: Department of Pathology, University of Valencia, Valencia, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Monteagudo
authors.affiliation: Dermatology Service, Fundación Instituto Valenciano de Oncología, Valencia, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Llombart
authors.affiliation: Department of Pathology, University of Valencia, Valencia, Spain.
authors.forename: Octavio
authors.initials: O
authors.lastname: Burgués
authors.affiliation: Molecular Biology Unit, Fundación Instituto Valenciano de Oncología, Valencia, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Rubio
authors.affiliation: Department of Pathology, University of Valencia, Valencia, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Calabuig
authors.affiliation: Dermatology Service, Fundación Instituto Valenciano de Oncología, Valencia, Spain.
authors.forename: Onofre
authors.initials: O
authors.lastname: Sanmartín
authors.affiliation: Molecular Biology Unit, Fundación Instituto Valenciano de Oncología, Valencia, Spain.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: López-Guerrero
mesh_terms: D002471:Cell Transformation, Neoplastic; D018223:Dermatofibrosarcoma / Q000235:genetics / Q000473:pathology*; D005354:Fibrosarcoma / Q000235:genetics / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism; D011379:Prognosis; D012878:Skin Neoplasms / Q000235:genetics / Q000473:pathology*
chemical_list: C120892:COLIA1-PDGFB fusion protein, human; D015514:Oncogene Proteins, Fusion
keywords: COL1A1-PDGFB fusion gene; FISH; FS-DFSP; dermatofibrosarcoma protuberans; fibrosarcoma