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International audience; Research Letter

Summary Background Dermatofibrosarcoma protuberans (DFSP) is an uncommon skin tumour with aggressive local growth. Whether DFSP should be treated with conventional surgery (CS) or Mohs micrographic surgery (MMS) has long been a topic of debate. Objectives To calculate, in a large series of DFSP treated by MMS, the minimum margin that would have been needed to achieve complete clearance by CS. Secondly, to calculate the percentage of healthy tissue that was preserved by MMS rather than CS with 2- and 3-cm margins. Methods The minimum margin was calculated by measuring the largest distance from the visible edge of the tumour to the edge of the definitive surgical defect. Tumour and surgical defect areas for hypothetical CS with 2- and 3-cm margins were calculated using AutoCAD for Windows. Results A mean minimum margin of 1·34 cm was required to achieve complete clearance for the 74 tumours analysed. The mean percentages of skin spared using MMS rather than CS with 2- and 3-cm margins were 49·4% and 67·9%, respectively. Conclusions MMS can achieve tumour clearance with smaller margins and greater preservation of healthy tissue than CS.

SummaryBackground Dermatofibrosarcoma protuberans (DFSP) is a rare malignant cutaneous tumour of which diagnosis is often delayed because of the lack of early clinical clues. Objectives To describe the main dermoscopic features of DFSP. Methods We performed dermoscopic examination in 15 unselected, consecutive cases of biopsy-proven DFSP. Firstly, six dermoscopic features were identified collegially, then all cases were reviewed separately by six experienced dermoscopists. In a given lesion, features recognized only by all dermoscopists were taken into account. Results The median number of dermoscopic features was four per lesion. The following dermoscopic features were found: delicate pigmented network (87%), vessels (80%), structureless light brown areas (73%), shiny white streaks (67%), pink background coloration (67%) and structureless hypo- or depigmented areas (60%). When detected, vessels were of arborizing type in 11 of 12 cases, and presented as either unfocused only, or both unfocused and focused. Conclusions This first study of the dermoscopic spectrum of DFSP identifies six dermoscopic features (often associated in a multicomponent pattern) and a peculiar vascular pattern. Whether dermoscopy can help to identify suspected DFSP remains to be established by further studies.

Summary Background Dermatofibrosarcoma protuberans (DFSP) has conventionally been treated with wide local excision. More recently Mohs micrographic surgery (MMS) has been advocated. Objectives To assess our departmental experience with DFSP in the context of a literature review relating to DFSP treated with MMS. Methods This was a case review of 35 patients with DFSP treated between 1998 and 2009 with MMS using paraffin-embedded sections. Results Seventeen patients required one horizontal layer to clear their tumour, 10 patients needed two and eight patients needed three layers or more. The median preoperative clinical size was 6 cm2 (range 0·75–54·8) and the median postoperative wound size was 46·8 cm2 (range 4–145·2). Tumour persistence has not been observed in any of our patients after a median follow-up duration of 29·5 months (range 6–146). Conclusions We present 35 DFSP patients, none of whom showed persistent tumour after treatment with ‘slow’ MMS using paraffin sections. We advocate MMS as the treatment of choice for DFSP, especially for tumours over the head and neck region where tissue conservation is particularly important.

Summary Background The distinction between dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) is a well-known challenge for dermatopathologists. Immunohistochemical stains have been used to augment routine histological examination to aid in differentiating DF from DFSP. Collagen triple helix repeat containing-1 (Cthrc1) was identified as a novel gene expressed in the adventitia and neointima on arterial injury. It is indicated to be a cell type-specific inhibitor of transforming growth factor-β, which in turn impacts collagen type I and III deposition, neointimal formation, and dedifferentiation of stem cells. Cthrc1 has also been shown to be highly active and potent in degrading extracellular matrix proteins and was found to be overexpressed in several malignant tumours, such as breast cancer and malignant melanoma. To our knowledge, however, expression of Cthrc1 in DFSP and DF has not been studied before. Objectives To assess the expression of Cthrc1 in DFSP and DF and to ascertain whether Cthrc1 is superior to antibodies traditionally used in differentiating DF from DFSP. Methods Immunohistochemical staining was performed on 23 cases of DFSP and 35 cases of DF, using antibodies to Cthrc1, CD34, factor XIIIa, CD10 and stromelysin-3 (ST3). Results Twenty-two of 23 (96%) DFSP samples were positive for Cthrc1, whereas 32 of 35 (91%) DF samples were negative. CD34 was expressed in most DFSPs (22 of 23, 96%), whereas it was completely negative in most cases of DF (29 of 35, 83%). Expression of factor XIIIa was found in most cases of DF (33 of 35, 94%), whereas it was completely absent in 21 of 23 (91%) DFSP cases. Expression of CD10 was found in most cases of DF (30 of 35, 86%), whereas it was completely absent in 13 of 23 (57%) DFSP cases. ST3 was expressed strongly in most cases of DF (32 of 35, 91%), whereas it was completely absent in 18 of 23 (78%) DFSP cases. The preferential Cthrc1 staining of DFSP in comparison with DF was statistically significant (P

Background Dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) are benign and intermediate malignant fibrotic dermal tumours, respectively. The contribution of transforming growth factor (TGF)-beta has been implicated in the progression of sclerosis in fibrotic diseases. Objectives To investigate the expression of TGF-beta receptors in these fibrotic tumours. Methods We examined the expression levels of TGF-beta type I and type II receptors (TGFbeta-RI and TGFbeta-RII) in DF and DFSP using in situ hybridization and immunohistochemical analysis. We also examined the expression of TGF-beta1 and collagen type I using immunohistochemical analysis. Results We detected strong expression of TGFbeta-RI and TGFbeta-RII on epidermis and epidermal appendages, moderate expression in vascular endothelial cells, smooth muscle cells and neural tissues, and weak expression in fibroblasts in normal skin sections. The expression levels of TGFbeta-RI and TGFbeta-RII were elevated in the tissue sections of DF in comparison with normal dermal sections using in situ hybridization and immunohistochemical staining. Furthermore, the expression of TGFbeta-RI and TGFbeta-RII was strong in spindle-shaped cells around DF. The expression of TGFbeta-RI and TGFbeta-RII was decreased in DFSP in comparison with DF, and their expression was found to be homogeneous in each DFSP tumour cell. The staining for TGF-beta1 was found prominently on matrix and spindle-shaped tumour cells of DF, and peripheral regions of DFSP. Weak expression of TGF-beta1 was found on normal skin or tumour cells in the central part of DFSP. Type I collagen expression was found on spindle-shaped tumour cells in DF, but not in tumour cells of DFSP. Conclusions These results suggest the possibility that TGF-beta signalling may contribute to the fibrosis around DF, and that TGF-beta receptors may play important roles in TGF-beta signalling. The expression patterns of TGFbeta-RI and TGFbeta-RII may be helpful in distinguishing these diseases.

Summary Background Fusion of the collagen type I α 1 (COL1A1) gene with the platelet-derived growth factor B-chain (PDGFB) gene has been described in dermatofibrosarcoma protuberans (DFSP). Various exons of the COL1A1 gene have been shown to be involved in the fusion with exon 2 of the PDGFB gene. Objectives We examined the breakpoint of the COL1A1 gene using the tumour specimen from the patient with DFSP. Methods Reverse transcriptase–polymerase chain reaction (PCR) was performed using cultured DFSP tumour cells. Nucleotide sequence analysis was carried out using the PCR product to identify the breakpoint. Results The COL1A1–PDGFB fusion transcript was detected from the tumour specimen. Sequence analysis revealed that exon 18 of the COL1A1 gene was fused with exon 2 of the PDGFB gene. Conclusions This study identified a novel COL1A1 breakpoint, namely, exon 18 of the COL1A1 gene.

Nodular sclerotic change in dermatofibrosarcoma protuberans (DFSP) is not a well-recognized event. Sclerotic change is reported in three patients with DFSP: a 33-year-old woman with a left subclavian mass, a 29-year-old woman with a mass on the left crus and a 31-year-old man with a mass on the left cheek. Histologically, lesions consisted of two types of feature, one type being typical of DFSP and the other being rich in collagen. In the first patient, each type formed a distinct compartment, each of which contained scattered cells containing melanin pigment. In the second patient, foci with typical DFSP histology were distributed within the collagen-rich area and also formed a substantial compartment in the periphery of the lesion, with pigmented cells being distributed mainly in and around the cellular area. In the third patient, the collagenous area occupied about half of the lesion. There was no pigmentation. In all three cases the collagen-rich area contained sparsely distributed fibroblast-like cells that stained positive with CD34. Sclerotic change in DFSP could cause substantial difficulty in diagnosis if the biopsy material were partial and small. The clinical history and knowledge about the existence of this kind of histological variation in DFSP are important.

Following the very recent description of a benign plaque-like myofibroblastic tumour of the skin, known as dermatomyofibroma, we present four further cases, emphasizing its clinical features and its histological differential diagnosis. Three patients were adult females and one was a boy. Two of the lesions arose on the anterior abdominal wall, one on the shoulder, and one on the neck. Clinically, there was often close resemblance to a keloid. Follow-up revealed no evidence of recurrence after simple excision. Histologically, these were non-encapsulated but well-circumscribed, plaque-like lesions located in the reticular dermis, and composed of fascicles of monomorphic myofibroblasts, orientated parallel to the skin surface. Immunohistochemically, most of the tumour cells expressed alpha-smooth-muscle actin. The principal differential diagnosis is plaque-stage dermatofibrosarcoma protuberans. Other differential diagnoses include diffuse neurofibroma, dermatofibroma and other myofibroblastic skin tumours.