No Correlation between the Molecular Subtype of COL1A1–PDGFB Fusion Gene and the Clinico-Histopathological Features of Dermatofibrosarcoma Protuberans

Epigenetics of Cutaneous Sarcoma

Epigenetic changes influence various physiological and pathological conditions in the human body. Recent advances in epigenetic studies of the skin have led to an appreciation of the importance of epigenetic modifications in skin diseases. Cutaneous sarcomas are intractable skin cancers, and there are no curative therapeutic options for the advanced forms of cutaneous sarcomas. In this review, we discuss the detailed molecular effects of epigenetic modifications on skin sarcomas, such as dermatofibrosarcoma protuberans, angiosarcoma, Kaposi's sarcoma, leiomyosarcoma, and liposarcoma. We also discuss the application of epigenetic-targeted therapy for skin sarcomas.

A case of dermatofibrosarcoma protuberans with neurofibromatous change

A 31-year-old man with posterior neck mass visited a hospital. The mass recurred four times on the same location during the past 6 years. Needle biopsy diagnosis was suspicious for benign stromal tumor. Tumor excision was performed 3 months after the biopsy. The tumor size was 8.3 × 4.5 cm and was located at subcutaneous tissue. Histologically, main tumor cells showed comma-shaped nuclei, which are same as neurofibroma. Immunohistochemically, tumor cells were positive for vimentin, CD34, but were negative for S-100. Fluorescence in situ hybridization analysis disclosed a split signal of PDGFB gene. Reverse transcriptase-polymerase chain reaction clarified COL1A1 exon 47/PDGFB exon 2 chimeric gene. Final diagnosis was dermatofibrosarcoma protuberans (DFSP) with neurofibromatous change. DFSP with neurofibromatous change is rare and could be misdiagnosed as benign tumor, especially in a biopsy specimen. Molecular diagnosis is a promising aid in a challenging case and in biopsy specimens.

DFSP of the Breast: Histomorphological, Immunohistochemical, and Molecular Features of a Rare Case in an Unusual Location

We present a case of a 21-year-old female with a vague nontender mass in the lower inner quadrant of the left breast discovered incidentally on chest imaging following trauma. A breast ultrasound demonstrated an 8×6×8 mm irregular hyperechoic mass at the 7 o'clock position of the left breast, 9 cm from the nipple. The mass was graded Breast Imaging Reporting and Data System (BI-RADS) category 4 (suspicious finding). An ultrasound-guided biopsy of the mass showed a proliferation of monotonous spindled cells in a storiform pattern with tapered nuclei with infiltration into the adipose tissue. No normal breast elements were identified in the biopsy. Myofibroblastoma was the first differential diagnosis; however, the characteristic infiltrative pattern of the tumor mandated additional tests including fluorescence in situ hybridization to rule out a dermatofibrosarcoma protruberance (DFSP). Immunohistochemical staining showed positive staining for CD34, which can be positive in myofibroblastoma also. However, fluorescence in situ hybridization demonstrated a platelet-derived growth factor B (22q13.1) gene rearrangement confirming a diagnosis of DFSP. The patient underwent a wide local excision of the DFSP for definitive treatment. She is doing well with no recurrence reported so far, after 15 months of follow-up. Conventional DFSP does not metastasize but is prone to recurrence making wide margins imperative for definitive treatment.

Determination of COL1A1-PDGFB breakpoints by next-generation sequencing in the molecular diagnosis of dermatofibrosarcoma protuberans

OBJECTIVE

In most cases, dermatofibrosarcoma protuberans (DFSP) is characterized by the chromosomal translocation t (17; 22) (q22; q13) that leads to a fusion of collagen type 1 alpha 1 (COL1A1) and platelet-derived growth factor beta chain (PDGFB). Recently, next-generation sequencing (NGS) has been reported to detect fusion transcripts in some malignancies. Therefore, the present study aimed to evaluate the utility of the targeted NGS in detecting the COL1A1-PDGFB fusion in patients with DFSP.

METHODS

We designed a targeted DNA capture panel to tile along the fusion regions, including exon, intron, and untranslated regions of the COL1A1 and PDGFB. A cohort of 18 DNA samples extracted from formalin-fixed, paraffin-embedded tissues was used to evaluate the targeted NGS. The results were compared with that of fluorescence in situ hybridization (FISH).

RESULTS

The COL1A1-PDGFB fusion was identified in 13 of 18 cases (72.2%) by targeted NGS assay. PDGFB breakpoints were constantly found in exon 2, while breakpoints in COL1A1 varied from exon 15 to 46. Of these 18 cases assayed by FISH, 12 (66.7%) exhibited COL1A1-PDGFB fusion signals. One case (P9), which was FISH-negative, was demonstrated with the fusion by targeted NGS and validated by PCR and Sanger sequencing. The targeted NGS results showed a high concordance with the results of the FISH assay (94.4%).

CONCLUSION

Our study reported a targeted NGS assay for detecting the breakpoints of the COL1A1-PDGFB fusion gene, which can be implemented in diagnosing patients with DFSP.

Fusion of the COL4A5 Gene With NR2F2-AS1 in a Hemangioma Carrying a t(X;15)(q22;q26) Chromosomal Translocation

BACKGROUND/AIM

Hemangiomas are benign neoplastic proliferations of blood vessels. Cytogenetic information on hemangiomas is limited to four tumors with abnormal karyotypes. We report here a solitary chromosomal translocation and its molecular consequence in a hemangioma.

MATERIALS AND METHODS

A cavernous hemangioma was extirpated from the foot of a 62 years old man and genetically studied with cytogenetic and molecular genetic methodologies.

RESULTS

G-Banding analysis of short-term cultured tumor cells yielded the karyotype 46,Y,t(X;15)(q22;q26)[4]/46,XY[12]. RNA sequencing detected fusion of the collagen type IV alpha 5 chain gene (COL4A5 on Xq22.3) with intronic sequences of nuclear receptor subfamily 2 group F member 2 antisense RNA 1 (NR2F2-AS1 on 15q26.2) resulting in a putative COL4A5 truncated protein. The fusion was verified by RT-PCR together with Sanger sequencing and FISH analyses.

CONCLUSION

The involvement of COL4A5 indicates that some hemangiomas have pathogenetic similarities with other benign tumors such as leiomyomas and subungual exostosis.

A Multicenter Phase II Study of Pazopanib in Patients with Unresectable Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DFSP) is a soft-tissue sarcoma characterized by a high risk of local infiltration. The identification of the COL1A1-PDGFB t(17;22) translocation activating the PDGF pathway led to the use of imatinib in unresectable DFSP, with a response rate of 36-80%. Pazopanib is a multitarget tyrosine kinase inhibitor approved for soft-tissue sarcomas. We conducted a phase II study of patients with unresectable DFSP to evaluate the efficacy and safety of pazopanib. Patients received 800 mg of pazopanib daily. The primary endpoint was the objective response rate defined as the reduction of the largest diameter of the tumor by ≥30% at 6 months or at surgery. A total of 23 patients, including one pretreated with imatinib, were enrolled. With a median follow-up of 6.2 months (interquartile range = 5.6-7.8 months), five patients (22%, 95% confidence interval = 7-22%) had a partial response to pazopanib. The best objective response rate was 30% (95% confidence interval = 13-53%) using Response Evaluation Criteria in Solid Tumors. One patient with metastatic DFSP previously treated with imatinib died after 2.4 months. Nine patients (39%) discontinued the treatment owing to adverse events. Pharmacodynamics analyses of tumor samples were conducted: the enrichment of EGF and the EGFR-associated gene panel was associated with resistance, suggesting that EGFR-targeted therapies could be a therapeutic option to explore in DFSP. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01059656.

Fusion of the COL1A1 and FYN Genes in Epithelioid Osteoblastoma

BACKGROUND/AIM

Epithelioid osteoblastoma is a rare benign tumor of the bone. Its pathogenesis is unknown and little is known regarding its genetic features.

MATERIALS AND METHODS

Cytogenetic, RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), genomic PCR, and Sanger sequencing analyses were performed on an epithelioid osteoblastoma.

RESULTS

G-banding analysis of short-term cultured tumor cells yielded a normal male karyotype in all examined metaphases. RNA sequencing detected a fusion of COL1A1 from 17q21 with FYN from 6q21. Both RT-PCR and genomic PCR together with Sanger sequencing verified the presence of a COL1A1-FYN fusion gene. In the COL1A1-FYN chimeric transcript, exon 43 of COL1A1 was fused to exon 2 of FYN. The genomic junction occurred in introns 43 and 1 of COL1A1 and FYN, respectively.

CONCLUSION

A COL1A1-FYN fusion gene was found in an epithelioid osteoblastoma resulting in deregulation of FYN. Whether COL1A1-FYN represents a consistent genetic feature of epithelioid osteoblastomas, remains to be seen.

Advances in chromosomal translocations and fusion genes in sarcomas and potential therapeutic applications

Chromosomal translocations and fusion genes are very common in human cancer especially in subtypes of sarcomas, such as rhabdomyosarcoma, Ewing's sarcoma, synovial sarcoma and liposarcoma. The discovery of novel chromosomal translocations and fusion genes in different tumors are due to the advancement of next-generation sequencing (NGS) technologies such as whole genome sequencing. Recently, many novel chromosomal translocations and gene fusions have been identified in different types of sarcoma through NGS approaches. In addition to previously known sarcoma fusion genes, these novel specific fusion genes and associated molecular events represent important targets for novel therapeutic approaches in the treatment of sarcomas. This review focuses on recent advances in chromosomal translocations and fusion genes in sarcomas and their potential therapeutic applications in the treatment of sarcomas.

Dermatofibrosarcoma protuberans of the breast: A case report

Dermatofibrosarcoma protuberans (DFSP) is a rare malignant tumor of subcutaneous tissue characterized by slow infiltrative growth. The tumor occurs in patients of all ages, with the highest frequency occurring between the second and the fifth decades of age. Genetically, DFSP is characterized by a reciprocal translocation t(17;22)(q22;q13), or more often, as a supernumerary ring chromosome involving chromosomes 17 and 22. Standard treatment of a localized tumor is surgical excision with wide margins. In the present study, a case report of a 43-year-old woman with a growing tumor in the left breast is discussed. The patient underwent breast-conserving surgery. Histological and cytogenetic examinations of the tumor resulted in a diagnosis of DFSP. The clinical and morphological characteristics of the tumor, in addition to the treatment options, were also evaluated.

Congenital atrophic dermatofibrosarcoma protuberans detected by COL1A1-PDGFB rearrangement

Background

Atrophic variant of dermatofibrosarcoma protuberans (DFSP) is a distinct form of DFSP.

Case presentation

Here, we report the case of a 19-year-old woman with a small congenital atrophic plaque on the right precordium. The lesion remained atrophic for more than 10 years. Several years earlier, a portion of the plaque became tuberous and enlarged. Physical examination revealed a 25 × 30 mm erythematous atrophic plaque surrounded by three hard, smooth, and orange-colored nodules of varying sizes on the right precordium, along with visible subcutaneous adipose tissue and cutaneous veins. Biopsy of the nodule and atrophic plaque revealed dense proliferation of spindle-shaped tumor cells from the dermis to the subcutaneous adipose tissue, and positive immunostaining for CD34 and vimentin in addition to negative staining for factor XIIIa and α-smooth muscle actin. Reverse transcription polymerase chain reaction (RT-PCR) of the tumor tissue revealed the presence of a COL1A1-PDGFB fusion gene. Thus, congenital atrophic dermatofibrosarcoma protuberans was diagnosed. No metastasis to the lungs or regional lymph nodes was found on magnetic resonance imaging. Wide local excision and split-thickness skin grafting was performed and neither recurrence nor metastasis has been observed for 5 years and 8 months since the surgery.

Conclusion

This case indicates that a congenital atrophic lesion could represent a quiescent phase of DFSP. Awareness of this rare condition can aid with early diagnosis and thereby improve the prognosis of DFSP.

Molecularly targeted therapies for nonmelanoma skin cancers

Over the past two decades, advances in the fields of cancer genetics and molecular biology have elucidated molecular pathways that cause numerous cutaneous malignancies. This in turn has spurred the rational design of molecularly targeted therapies. In this review, we discuss the molecular pathways critical to the development of nonmelanoma skin cancers and the novel pharmacologic agents that target them. Included is a review of vismodegib for basal cell carcinoma, cetuximab for squamous cell carcinomas, imatinib for dermatofibrosarcoma protuberans, and sirolimus for Kaposi's sarcoma.

PDGFB rearrangement in dermatofibrosarcoma protuberans: correlation with clinicopathologic characteristics and clinical implications

Dermatofibrosarcoma protuberans (DFSP) is characterized genetically by the translocation t(17;22)(q22;q13), which creates a COL1A1/PDGFB fusion gene. The implications of this gene for the clinicopathologic features of the disease are not fully understood. Fifty-one cases of DFSP from 46 patients were reclassified as DFSP (n=29) and DFSP-fibrosarcomatous variant (DFSP-FS; n=22). Fluorescence in situ hybridization was performed using a dual-color break-apart probe to detect rearrangements involving PDGFB, and CD34 immunohistochemistry staining was done. The DFSP-FS was found in older patients, and the tumors were larger, with a smaller mean area of staining for CD34. PDGFB rearrangement was found in 45 cases (95.7%). The mean gene copy number was 3.82 (range 2.2-6.45) and was higher in DFSP-FS than in classic DFSP (4.54 vs. 3.47; P < .001). The PDGFB copy number showed a moderate positive correlation with the number of mitotic figures and tumor size. Patients undergoing wide excision or having no involvement of the resection margin had no relapses. These results suggest a role for COL1A1/PDGFB in sarcomatous change in DFSP over time. Detection of COL1A1/PDGFB rearrangement by fluorescence in situ hybridization is useful for confirmation of the diagnosis. Patients who present with metastatic DFSP-FS show less typical histologic findings and loss of CD34 staining, leaving PDGFB rearrangement as the preferred adjunctive method for diagnosis from small biopsies and for prediction of the value of imatinib therapy.

Pediatric sarcomas: translating molecular pathogenesis of disease to novel therapeutic possibilities

Pediatric sarcomas represent a diverse group of rare bone and soft tissue malignancies. Although the molecular mechanisms that propel the development of these cancers are not well understood, identification of tumor-specific translocations in many sarcomas has provided significant insight into their tumorigenesis. Each fusion protein resulting from these chromosomal translocations is thought to act as a driving force in the tumor, either as an aberrant transcription factor (TF), constitutively active growth factor, or ligand-independent receptor tyrosine kinase. Identification of transcriptional targets or signaling pathways modulated by these oncogenic fusions has led to the discovery of potential therapeutic targets. Some of these targets have shown considerable promise in preclinical models and are currently being tested in clinical trials. This review summarizes the molecular pathology of a subset of pediatric sarcomas with tumor-associated translocations and how increased understanding at the molecular level is being translated to novel therapeutic advances.

Cytogenetics and molecular genetics of myxoid soft-tissue sarcomas

Myxoid soft-tissue sarcomas represent a heterogeneous group of mesenchymal tumors characterized by a predominantly myxoid matrix, including myxoid liposarcoma (MLS), low-grade fibromyxoid sarcoma (LGFMS), extraskeletal myxoid chondrosarcoma (EMC), myxofibrosarcoma, myxoinflammatory fibroblastic sarcoma (MIFS), and myxoid dermatofibrosarcoma protuberans (DFSP). Cytogenetic and molecular genetic analyses have shown that many of these sarcomas are characterized by recurrent chromosomal translocations resulting in highly specific fusion genes (e.g., FUS-DDIT3 in MLS, FUS-CREB3L2 in LGFMS, EWSR1-NR4A3 in EMC, and COL1A1-PDGFB in myxoid DFSP). Moreover, recent molecular analysis has demonstrated a translocation t(1; 10)(p22; q24) resulting in transcriptional upregulation of FGF8 and NPM3 in MIFS. Most recently, the presence of TGFBR3 and MGEA5 rearrangements has been identified in a subset of MIFS. These genetic alterations can be utilized as an adjunct in diagnostically challenging cases. In contrast, most myxofibrosarcomas have complex karyotypes lacking specific genetic alterations. This paper focuses on the cytogenetic and molecular genetic findings of myxoid soft-tissue sarcomas as well as their clinicopathological characteristics.

Dermatofibrosarcoma protuberans: a clinicopathological, immunohistochemical, genetic (COL1A1-PDGFB), and therapeutic study of low-grade versus high-grade (fibrosarcomatous) tumors

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is an uncommon cutaneous tumor, usually low grade, except for the fibrosarcomatous variant (DFSP-FS).

OBJECTIVES

We sought to compare the clinicopathological, immunohistochemical, genetic, and therapeutic features between DFSP and DFSP-FS.

METHODS

The clinicopathological features were reviewed in 63 DFSP and 12 DFSP-FS. Immunohistochemistry and multiplex reverse transcriptase-polymerase chain reaction were carried out using formalin-fixed, paraffin-embedded tissue, using specific primers for collagen type I alpha 1 (COL1A1) and platelet-derived growth factor beta (PDGFB).

RESULTS

DFSP-FS was associated with tumor history longer than 5 years (P = .009), tumor size greater than 4 cm (P = .001), more stages of modified Mohs micrographic surgery (P = .005), expansive subcutaneous infiltration (P = .005), muscular invasion (P = .0001), absence of CD34 staining (P = .018), p53 positivity (P = .006), and increased proliferative activity (P = .004) compared with DFSP. The COL1A1-PDGFB fusion transcript was found in 100% DFSP-FS and 72% DFSP. No association was found between the different COL1A1-PDGFB fusion transcripts and the different histologic subtypes. Wide local excision (2 cm) was performed in 47% of cases and modified Mohs micrographic surgery in 53%. After a mean follow-up of 73 months (range 21-235), 6 patients had local recurrence (5 DFSP, 1 DFSP-FS) and one died of disease (DFSP-FS). The only factor related to local recurrence was the type of surgery (17% wide local excision vs 0% modified Mohs micrographic surgery) (P = .006).

LIMITATIONS

Our study is retrospective. Prospective studies are necessary to confirm our results.

CONCLUSIONS

DFSP-FS reflects tumor progression in DFSP, with larger size, particular invasive patterns, p53 expression, and increased proliferative activity. However, as in low-grade DFSP, appropriate surgery permits a tumor-free excision. COL1A1-PDGFB is a useful tool for diagnosis of DFSP and particularly for DFSP-FS.

Late local recurrence of dermatofibrosarcoma protuberans in the skin of female breast

Dermatofibrosarcoma protuberans (DFSP) of the breast is exceptionally obscure and late local recurrence of this entity on this site is even more uncommon. We describe such a case in a 48-year-old woman, who at the age of 35 had a DFSP excised from her right breast. Thirteen years later, she developed an ovoid mass in her right breast over the postsurgical scar area. Wide local excision of the tumor with generous tissue margin was performed and microscopic and immunohistochemical findings established the diagnosis of recurrent DFSP. No further treatment was administered and she remains well 18 months later, without tumor recurrence. We report an exceptionally rare case of local recurrence of DFSP in the female breast and discuss in detail the diagnostic and therapeutic implications of this pathology.