Another case of t(17;22)(q22;q13) in an infantile dermatofibrosarcoma protuberans

Dermatofibrosarcoma Protuberans-Like Tumor With COL1A1 Copy Number Gain in the Absence of t(17;22)

A 57-year-old woman presented with a 3-year history of a progressive firm plaque on the right cheek. Skin biopsies revealed a bland, storiform, spindle-cell proliferation involving the deep dermis and subcutaneous fat. By immunohistochemistry, the tumor cells were diffusely positive for CD34 and caldesmon with multifocal reactivity for epithelial membrane antigen and focal, weak staining for smooth muscle actin. Retinoblastoma protein expression was not detectable in tumor cells by immunohistochemistry. An interphase fluorescence in situ hybridization analysis for platelet-derived growth factor B (PDGFB) gene rearrangement was negative. A single-nucleotide polymorphism array study detected 1) a gain of chromosome segment 17q21.33-q25.3 which overlapped the entire COL1A1 gene with a breakpoint at 17q21.33, approximately 250 Kb centromeric to the 3' end of COL1A1 gene, 2) several segmental gains on chromosome 11, and 3) an RB1 gene locus with normal copy number and allele frequency. Although the current case resembles dermatofibrosarcoma protuberans, it is unique in that it demonstrates a copy number gain of chromosome 17q in the absence of fusion of COL1A1 and PDGFB genes and an unusual immunohistochemical staining profile. The morphologic and molecular findings suggest a novel molecular variant of dermatofibrosarcoma protuberans not detectable with standard fluorescence in situ hybridization for PDGFB rearrangement. This variant appears to respond to imatinib after 9 months of follow-up.

Current treatment options for dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is rare, infiltrating dermal neoplasm, characterized by indolent growth and low probability of metastases. The critical event in DFSP development is the rearrangement of chromosome 17 and 22, leading to transcriptional up-regulation of platelet-derived growth factor, providing an autocrine and/or paracrine stimulus. The cornerstone of treatment for localized DFSP is complete surgical resection with microscopically negative margins. Adjuvant radiotherapy is suggested in cases of positive margins when re-excision is not feasible. The first effective systemic therapy in DFSP introduced into clinical practice was imatinib, demonstrating dramatic activity in advanced cases. Current results indicate that some DFSP patient initially evaluated as unresectable/metastatic or necessitating mutilating surgery turned resectable after imatinib therapy and this rational approach leading to complete remission maybe potentially curative. The clinical experience with other tyrosine kinase inhibitors is limited and imatinib remains the gold standard treatment of locally unresectable/metastatic DFSP. This review summarizes state of the art and perspectives on the DFSP management.

Dermatofibrosarcoma protuberans in an adolescent: a case report and review of the literature

Classically, dermatofibrosarcoma protuberans (DFSP) is a disease of adults. The world literature revision shows that several pediatric cases have been reported so far; this might suggest that the number of infants with the condition might be larger than that estimated previously. Here, we report the 183rd case of histologically confirmed DFSP in young age. A 14-year-old white male patient came under our care for a slowly growing, pale brownish lesion on the neck skin. A biopsy specimen showed a DFSP. Subsequently, a wide surgery excision with 3 cm of resection margins including the underlying fascia was performed. To date, the patient has been in follow-up for 6 years without evidence of recurrent disease. The clinical features and treatment of DFSP diagnosed in childhood and adolescence reported in the published literature are reviewed to provide new insights about this rare entity. The aim is to emphasize the importance of biopsy for histologic evaluation in the cases that show a persistent or a large cutaneous plaque or nodule without pathognomonic clinical features that permit a clinical diagnosis. An accurate knowledge of the disease is the prerequisite for a wider recognition and appropriate treatment.

Advances in molecular characterization and targeted therapy in dermatofibrosarcoma protuberans

The molecular pathogenesis of dermatofibrosarcoma protuberans (DFSP) involves distinctive rearrangement of chromosomes 17 and 22 leading to formation of the COL1A1-PDGFB fusion gene. The knowledge of molecular events underlying development of DFSP resulted in the implementation of targeted therapy with imatinib—a tyrosine kinase inhibitor (TKI), to the clinical practice. The striking efficacy of imatinib in advanced cases of DFSP has been demonstrated in a few clinical trials. Thus, imatinib is currently considered the gold standard in the treatment of inoperable and/or metastatic and/or recurrent cases of DFSP. Therapy with imatinib may potentially facilitate resection or decrease possible disfigurement related to radical surgical procedure. Following partial response on imatinib significant percentage of patients may be rendered free of the disease by surgery of the residual tumor.

Imatinib mesylate in advanced dermatofibrosarcoma protuberans: pooled analysis of two phase II clinical trials

PURPOSE

Dermatofibrosarcoma protuberans (DFSP) is a dermal sarcoma typically carrying a translocation between chromosomes 17 and 22 that generates functional platelet-derived growth factor B (PDGFB).

PATIENTS AND METHODS

Two distinct phase II trials of imatinib (400 to 800 mg daily) in patients with locally advanced or metastatic DFSP were conducted and closed prematurely, one in Europe (European Organisation for Research and Treatment of Cancer [EORTC]) with 14-week progression-free rate as the primary end point and the other in North America (Southwest Oncology Group [SWOG]) with confirmed objective response rate as the primary end point. In the EORTC trial, confirmation of PDGFB rearrangement was required, and surgery was undertaken after 14 weeks if feasible. The SWOG study confirmed t(17;22) after enrollment.

RESULTS

Sixteen and eight patients were enrolled onto the EORTC and SWOG trials, respectively. Tumor size ranged from 1.2 to 49 cm. DFSP was located on head/neck, trunk, and limb in seven, 11, and six patients, respectively, and was classic, pigmented, and fibrosarcomatous DFSP in 13, one, and nine patients, respectively. Metastases were present in seven patients (lung involvement was present six patients). Eleven patients (4%) had partial response as best response, and four patients had progressive disease as best response. Median time to progression (TTP) was 1.7 years. Imatinib was stopped in 11 patients because of progression, one patient because of toxicity, and two patients after complete resection of disease. Median overall survival (OS) time has not been reached; 1-year OS rate was 87.5%.

CONCLUSION

Imatinib is active in DFSP harboring t(17;22) including fibrosarcomatous DFSP, with objective response rate approaching 50%. Response rates and TTP did not differ between patients taking 400 mg daily versus 400 mg twice a day.

Sarcomes des tissus mous : données moléculaires actuelles

Soft tissue sarcomas are rare and may be a source of problems for diagnosis and treatment. Four types of genetic disorders can be distinguished: translocations, gene amplifications, mutations and complex genetic imbalances. Detection of these disorders may help in diagnosis and in determining prognosis. Detection of specific translocation is recommended in synovial sarcoma, alveolar rhabdomyosarcoma or PNET diagnosis because of therapeutic consequences; in case of rarer histologic type (low grade fibromyxoid sarcoma, clear cell sarcoma, infantile fibrosarcoma...), it may confirm the diagnosis. In some cases, some translocations have a prognostic value (alveolar rhabdomyosarcoma) whereas it is discussed in others (synovial sarcoma). The techniques used to detect these translocations are very sensitive so it may be used to detect microscopical metastasis (bone marrow metastasis of alveolar rhabdomyosarcoma for example). Detection of MDM2 and CDK4 genes amplifications (FISH or quantitative PCR) may be sometimes useful in well differentiated and dedifferentiated liposarcomas diagnosis. Mutation detection of KIT or PDGFRA may help in GIST diagnosis and type of mutation is predictive of response to treatment. Study of complex genomic imbalances in sarcomas is not used in routine practice but remains useful in research.

Chemosensitivity in pediatric dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a rare tumor of fibrohistiocytic spectrum and uncommonly presents in infancy and childhood. The standard treatment is wide-margin surgical excision, but this is difficult to achieve in large tumors and may result in unacceptable cosmetic, structural, and functional consequences. The authors describe a child with recurring DFSP who, after extensive surgery, responded to treatment with vinblastine and oral methotrexate. This is the first reported case in literature of a chemotherapeutic response in pediatric DFSP.

Dermatofibrosarcoma protuberans at the site of a central venous line. Case report

Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive cutaneous tumor that usually does not metastasize. Clinically, it may present as a reddish macule to protuberant nodule affecting the trunk and proximal extremities of young and middle-aged adults. Histologically, it is characterized by a monomorphous storiform proliferation of spindle cells, involving the dermis and hypodermis, with a honeycomb pattern of infiltration of the subcutaneous fat. In case of difficulty in diagnosis, immunohistochemical markers (especially CD34) are highly sensitive for DFSP. It is important to remember that the rarity of DFSP, its resemblance to hypertrophied scars and keloids, and its appearance at trauma sites sometimes make the diagnosis of DFSP difficult and delayed. In the literature, DSFP was not described in a child until 1957. Here we report an instance of DFSP at an unusual site in a 9-year-old child, which was the location of a previous central venous line insertion in the left supraclavicular area. A complete excision of the tumor with a wide surgical margin of 3cm of visibly uninvolved tissue was performed, followed by a deltopectoral flap and skin split graft. Postoperatively, the patient's general condition was stable and he was discharged after 5 days to be followed up 3 months later in our clinic.

A case of childhood dermatofibrosarcoma protuberans without detected cytogenetic abnormality

Dermatofibrosarcoma protuberans (DFSP) is a rare, infiltrative skin tumour of intermediate malignancy, with a limited potential for metastasis but a high rate of recurrence; specific cytogenetic abnormalities are now known. Childhood DFSP has been considered a rarity in the past, but it is now recognized that many cases of childhood DFSP are diagnosed only in adulthood. Despite advances in the understanding of its pathogenesis as well as the development of valuable immunohistochemical and cytogenetic diagnostic techniques, there often remains a significant delay between the initial presentation and diagnosis of DFSP. We report a case of childhood DFSP in which the diagnosis was reached only after a nodular lesion developed in a plaque that was initially present. Causes for delay between initial presentation and diagnosis in childhood DFSP are discussed. Histology and immunostaining in our patient showed the typical features of DFSP, but the G-banded cytogenetic analysis of short-term tissue culture was negative. However, this technique offers only a detection rate between 50% and 80%. Clinicians should be aware of the limitations of newer diagnostic techniques. Increasing recognition amongst paediatricians and paediatric dermatologists that childhood DFSP is not as rare as once believed will probably lead to the use of newer diagnostic methods at an earlier stage, and so reduce the delay between the onset of symptoms and diagnosis.

Genetics of dermatofibrosarcoma protuberans family of tumors: from ring chromosomes to tyrosine kinase inhibitor treatment

Dermatofibrosarcoma protuberans (DP) is a rare, slow-growing, infiltrating dermal neoplasm of intermediate malignancy, made up of spindle-shaped tumor cells often positive for CD34. The preferred treatment is wide surgical excision with pathologically negative margins. At the cytogenetic level, DP cells are characterized by either supernumerary ring chromosomes, which have been shown by using fluorescence in situ hybridization techniques to be derived from chromosome 22 and to contain low-level amplified sequences from 17q22-qter and 22q10-q13.1, or t(17;22), that are most often unbalanced. Both the rings and linear der(22) contain a specific fusion of COL1A1 with PDGFB. Similar to other tumors, the COL1A1-PDGFB fusion is occasionally cryptic, associated with complex chromosomal rearrangements. Although rings have been mainly observed in adults, translocations have been reported in all pediatric cases. DP is therefore a unique example of a tumor in which (i) the same molecular event occurs either on rings or linear translocation derivatives, (ii) the chromosomal abnormalities display an age-related pattern, and (iii) the presence of the specific fusion gene is associated with the gain of chromosomal segments, probably taking advantage of gene dosage effects. In all DP cases that underwent molecular investigations, the breakpoint localization in PDGFB was found to be remarkably constant, placing exon 2 under the control of the COL1A1 promoter. In contrast, the COL1A1 breakpoint was found to be variably located within the exons of the alpha-helical coding region (exons 6-49). No preferential COL1A1 breakpoint and no correlation between the breakpoint location and the age of the patient or any clinical or histological particularity have been described. The COL1A1-PDGFB fusion is detectable by multiplex RT-PCR with a combination of forward primers designed from a variety of COL1A1 exons and one reverse primer from PDGFB exon 2. Recent studies have determined the molecular identity of "classical" DP, giant cell fibroblastoma, Bednar tumor, adult superficial fibrosarcoma, and the granular cell variant of DP. In approximately 8% of DP cases, the COL1A1-PDGFB fusion is not found, suggesting that genes other than COL1A1 or PDGFB might be involved in a subset of cases. It has been proposed that PDGFB acts as a mitogen in DP cells by autocrine stimulation of the PDGF receptor. It is encouraging that inhibitory effects of the PDGF receptor tyrosine kinase antagonist imatinib mesylate have been demonstrated in vivo; such targeted therapies might be warranted in the near future for treatment of the few DP cases not manageable by surgery.

Dermatofibrosarcoma protuberans, giant cell fibroblastoma, and hybrid lesions in children: clinicopathologic comparative analysis of 28 cases with molecular data--a study from the French Federation of Cancer Centers Sarcoma Group

The clinicopathologic and immunohistochemical features of 28 dermatofibrosarcoma protuberans (DFSP), giant cell fibroblastomas (GCFs), and hybrid lesions occurring in children are presented, including molecular data for seven of them. There were 19 pure adult-type DFSP (9 male and 10 female patients aged between a few days [neonate] and 13 years, median 7 years), 5 pure GCF (all males aged from 2 to 8 years, median 4 years), and 4 hybrid tumors (all males aged from 1 to 4 years, median 2.5 years). Tumor locations in pure adult-type DFSP included the trunk (6) and lower (11) and upper (2) limbs. Pure GCFs were observed on the trunk (4) and knee (1), and hybrid lesions on the trunk (2) and lower (1) and upper (1) extremities. Tumor size (n = 20) ranged from 0.6 to 5 cm (median 2 cm). Histologically, pure DFSP presented as monotonous and infiltrative, low-grade, dermal/hypodermal storiform spindle cell proliferations, sparing adnexal structures. GCF showed a dense fibrous to myxoid matrix containing slender wavy spindle cells and multinucleated giant stromal cells often lining angiectoid spaces. Hybrid lesions showed varying combinations of DFSP and GCF areas. Mitotic activity ranged from 1 to 3 mitoses per 10 high power fields. All tumors were diffusely positive for vimentin and CD34 but negative for smooth muscle actin, desmin, epithelial membrane antigen, and cytokeratins; one pure adult-type DFSP was also S-100 protein positive; <1% of nuclei were Ki67 (Mib-1) positive. One karyotyped adult-type DFSP showed an unbalanced t(17;22) (q22;q13) translocation. Multiplex RT-PCR analysis and sequencing of PCR products in seven cases showed gene fusion transcripts in two pure DFSP, two pure GCFs, and one hybrid lesion. Results were uncertain in one pure GCF; one adult-type DFSP was negative. Treatment procedures were known for 27 patients, consisting of 16 wide excisions and 11 marginal excisions. Follow-up information on 15 widely excised tumors (median 24 months; range 5-144 months) showed no recurrence. Five of six marginally excised lesions with available follow up recurred 2 months to 6 years (median 2 years) after initial surgery; all but one were cured by wide reexcision. None of the tumors metastasized. In conclusion, this study emphasizes 1) the occurrence of adult-type DFSP in children, 2) the close relationship between DFSP and GCF clinically, histologically, and molecularly, 3) the excellent prognostic of these lesions if widely excised, and 4) the diagnostic usefulness of RT-PCR analyses in detecting the gene fusion transcripts resulting from the t(17;22) (q22;q13) in paraffin-embedded tissues.

Fusion of COL1A1 exon 29 with PDGFB exon 2 in a der(22)t(17;22) in a pediatric giant cell fibroblastoma with a pigmented Bednar tumor component. Evidence for age-related chromosomal pattern in dermatofibrosarcoma protuberans and related tumors

In contrast with classic dermatofibrosarcoma protuberans (DP), genetic information about the juvenile or pigmented variant forms of DP, so-called giant cell fibroblastoma (GCF) and Bednar tumor (BT), is limited. In the sole karyotyped case of BT a supernumerary ring containing chromosomes 17 and 22 sequences, similar to DP rings, was reported, whereas in three GCF cases, t(17;22) or der(22)t(17;22) with COL1A1-PDGFB fusion involving exons 11, 40, and 47, respectively, have been described. Here, we report the first cytogenetic and molecular analysis of a tumor from a 5-year-old child that contained both GCF and BT components. The karyotype and molecular analyses confirmed the common histogenetic origin between DP, GCF, and BT in showing the presence of a der(22)t(17;22) fusing the COL1A1 exon 29 to PDGFB exon 2. Because COL1A1 exon 29 has been involved previously in gene fusion with PDGFB exon 2 in several cases of adult or infantile DP presenting either t(17;22) or ring chromosomes, our results support the concept that DP, GCF, and BT are morphologic variants of a same entity, rather than distinct tumors. Of interest, our findings give prominence to the relation between patient age and the chromosomal rearrangement pattern in DP and related tumors. Whereas only a few adult DP cases presented with translocations, all the infantile cases, either DP, GCF, or mixed BT-GCF, as shown here, contained translocation derivatives but not ring chromosomes. All the ring chromosomes were observed in adult cases. With respect to cytogenetic studies, DP, GCF, and BT appear to be a unique model for age-related chromosomal rearrangement progression.

Overrepresentation of 17q22-qter and 22q13 in dermatofibrosarcoma protuberans but not in dermatofibroma: a comparative genomic hybridization study

Histopathological differentiation between dermatofibrosarcoma protuberans (DFSP) and dermatofibroma (DF) is often difficult, because both neoplasms share some clinical features and the presence of a storiform pattern. In the present study, we investigated the usefulness of comparative genomic hybridization (CGH) in the diagnosis of these entities by examining 12 DFSP and 12 DF cases. The most frequent DNA sequence copy number changes detected in 10 (83%) of 12 DFSP cases (mean, 1.9 aberrations/tumor; range, 0-3) consisted of gains of 17q22-qter (10 tumors), 22q13 (nine tumors), and 8q24.1-qter (three tumors). High-level amplification, which was detected in three tumors, was seen only in chromosome 17, with 17q23-q25 as the minimal common region. Loss of DNA sequences was not found in DFSP cases. In contrast, two (17%) of the 12 DF cases (mean, 0.5 aberrations/tumor; range, 0-4) showed DNA sequence copy number changes, although recurrent gains and losses and high-level amplifications were not observed. Gains were more common than losses in DF. Overrepresentation of 17q and 22q sequences was a common finding in DFSP but not in DF. Thus, CGH seems to be useful for distinguishing DFSP from DF in most cases.

Supernumerary ring chromosomes in dermatofibrosarcoma protuberans may contain sequences from 8q11.2-qter and 17q21-qter: a combined cytogenetic and comparative genomic hybridization study

Dermatofibrosarcoma protuberans (DFSP) presents with characteristic cytogenetic features such as reciprocal t(17;22)(q22;q13) or, more commonly, supernumerary ring chromosomes containing sequences from chromosomes 17 and 22. Here, we report the identification of a novel abnormality in a 43-year-old woman with DFSP. Cytogenetic analysis of tumor cells showed the presence of a supernumerary ring chromosome as the sole anomaly. Amplification of 8q11.2 approximately qter and 17q21 approximately qter sequences was confirmed by comparative genomic hybridization (CGH); the present case apparently lacked amplification of chromosome 22. To our knowledge, this is the first case indicating that the ring chromosome in DFSP is possibly associated with amplified material from chromosomes 8 and 17.

Spectral karyotyping reveals 17;22 fusions in a cytogenetically atypical dermatofibrosarcoma protuberans with a large marker chromosome as a sole abnormality

The presence of an extra ring chromosome containing material from 17q and 22q, or, less frequently, a t(17;22)(q22;q13), is a cytogenetic hallmark of dermatofibrosarcoma protuberans (DFSP). However, occasionally tumors with other, atypical karyotypes are encountered. We describe a case of recurrent DFSP without a ring chromosome or a t(17;22) on standard cytogenetic analysis. In all cells analyzed by G-banding, an additional, large marker chromosome was present as a sole abnormality. This chromosome apparently included chromosome 8 or the 8q arm, but the origin of its remaining part could not be determined with certainty. To characterize further the abnormal chromosome, we applied spectral karyotyping (SKY). SKY confirmed the presence of an extra chromosome 8 or arm 8q in the marker and showed that its remaining part was composed of segments from chromosomes 7, 17, 21, and 22, with two copies of a 17;22 fusion. Our results and the literature data suggest that, in addition to a specific 17;22 fusion, amplification of material from chromosomes 17, 22, 8, 5, 7, and 21 may play a role in DFSP development and/or progression. Furthermore, our case demonstrates the usefulness of SKY in detection of a diagnostically relevant 17;22 fusion in DFSP patients who have unusual karyotypic features.

Congenital and childhood dermatofibrosarcoma protuberans: a case report and review of the literature

Dermatofibrosarcoma protuberans (DFSP) occurs most commonly on the trunk, affects all races, and often develops between the second and fifth decades of life. It is uncommon in childhood and is sometimes mistaken for a vascular lesion, as it often presents as a blue macule or small nodule. Review of the English literature revealed approximately 152 cases of DFSP developing before 16 years of age and only 19 claimed congenital cases. A case of congenital dermatofibrosarcoma protuberans is presented with a literature review and discussion of congenital and childhood presentations of the tumor.

Fusion genes in solid tumors

Tumor development in different cell types and tissue locations involves many pathways, distinct genes and exogenous factors. Tumor type-specific chromosome rearrangements resulting in fusion genes or promoter swapping are believed to be involved in the early development of many tumor types. They are present in almost all cases of a particular tumor type and cases have been described that carry only tumor type-specific translocations without any signs of other cytogenetic changes. The mechanisms behind chromosome rearrangements in solid tumors are largely unknown. Radiation is an important factor in thyroid carcinomas but no com-$bmon sequence motifs are made out in the break points of solid tumors. The fusion genes found in sarcomas are dominated by the transcription factor type of genes with the TLS/FUS and EWS series of fusion genes as the largest group. More than 50% of papillary thyroid carcinomas carry fusion proteins with tyrosine kinase activity. Rearrangements involving HMGIC, HMGIY, and PLAG1 are common in benign mesenchymal tumors and salivary gland adenomas. Many recurrent tumor translocations show a strict specificity for tumor type. This specificity can most likely be explained by the specific sets of target genes that are deregulated by the fusion gene products. Identification of the downstream target genes is currently the object of intense research and may provide us with information that will help design better diagnostic tools and eventually find a cure for these diseases.

Cancer surveillance series: recent trends in childhood cancer incidence and mortality in the United States

BACKGROUND

Public concern about possible increases in childhood cancer incidence in the United States led us to examine recent incidence and mortality patterns.

METHODS

Cancers diagnosed in 14540 children under age 15 years from 1975 through 1995 and reported to nine population-based registries in the National Cancer Institute's Surveillance, Epidemiology, and End Results Program were investigated. Age-adjusted incidence was analyzed according to anatomic site and histologic categories of the International Classification of Childhood Cancer. Age-adjusted U.S. mortality rates were calculated. Trends in rates were evaluated by use of standard regression methods.

RESULTS

A modest rise in the incidence of leukemia, the most common childhood cancer, was largely due to an abrupt increase from 1983 to 1984; rates have decreased slightly since 1989. For brain and other central nervous system (CNS) cancers, incidence rose modestly, although statistically significantly (two-sided P = .020), largely from 1983 through 1986. A few rare childhood cancers demonstrated upward trends (e.g., the 40% of skin cancers designated as dermatofibrosarcomas, adrenal neuroblastomas, and retinoblastomas, the latter two in infants only). In contrast, incidence decreased modestly but statistically significantly for Hodgkin's disease (two-sided P = .037). Mortality rates declined steadily for all major childhood cancer categories, although less rapidly for brain/CNS cancers.

CONCLUSIONS

There was no substantial change in incidence for the major pediatric cancers, and rates have remained relatively stable since the mid-1980s. The modest increases that were observed for brain/CNS cancers, leukemia, and infant neuroblastoma were confined to the mid-1980s. The patterns suggest that the increases likely reflected diagnostic improvements or reporting changes. Dramatic declines in childhood cancer mortality represent treatment-related improvements in survival.

A case of dermatofibrosarcoma protuberans with a ring chromosome 5 and a rearranged chromosome 22 containing amplified COL1A1 and PDGFB sequences

Dermatofibrosarcoma protuberans (DFSP) is a cutaneous tumour of borderline malignancy, the cytogenetic features of which include the translocation t(17;22)(q22;q13) or, more commonly, supernumerary ring chromosomes containing material from 17q22 and 22q13. These rearrangements result in the COL1A1/PDGFB fusion gene. Here, we describe a case of DFSP displaying a ring chromosome 5 together with a large marker chromosome composed of chromosome 22 alphoid DNA, material from distal 12q and amplified COL1A1 and PDGFB sequences. This is the first case of DFSP with multiple copies of COL1A1 and PDGFB not confined to ring chromosomes, showing that DFSP is similar to other borderline malignant mesenchymal tumours, where rings and giant markers are alternative vehicles for amplified material.

Dermatofibrosarcoma protuberans: the pediatric experience at St. Jude Children's Research Hospital

The clinical characteristics and outcome of children with dermatofibrosarcoma protuberans (DFSP) treated at a single institution over a 34-year period were reviewed. A retrospective chart review identified five children with dermatofibrosarcoma protuberans. The diagnosis was confirmed in all cases by one of the authors. Age; sex; clinical group; tumor invasiveness and size, nodal status, and metastases (TNM stage); therapy; and outcome were retrieved from the medical records of these patients. The median age at diagnosis was 12.5 years. There were four boys, and all tumors arose in the extremities or trunk. All children underwent at least two surgical procedures to achieve negative or surgically microscopic positive margins. In addition, one patient received adjuvant radiotherapy for microscopically positive margins. All patients survive free of disease 1 month to 16.5 years after diagnosis. Dermatofibrosarcoma protuberans is rare among children and adolescents. Recognition of this pathologic entity is important for its proper treatment. Surgical resection (with 3-cm margins) is currently the standard therapy for DFSP.

Cellular fibrous histiocytoma of the skin: evidence of a clonal process with different karyotype from dermatofibrosarcoma

Recently, a distinct variant of cutaneous fibrous histiocytoma (FH) has been histologically characterized as a "cellular" subtype. This variant is often mistaken for sarcoma, including dermatofibrosarcoma protuberans. We report a case of cellular FH of the skin in which the cytogenetic analysis demonstrated a novel chromosome pattern, possibly allowing distinction from its histologic simulants.