Angiomatoid fibrous histiocytoma (AFH) is a soft tissue tumour of intermediate (rarely metastasising) malignant potential, which harbours EWSR1/FUS gene fusions. These tumours can express anaplastic lymphoma kinase (ALK) in the absence of gene rearrangement or copy number alteration and can also coexpresses Pan-TRK immunohistochemistry (IHC). All EWSR1/FUS-rearranged AFH were retrieved from the files of three institutions and Pan-TRK (EPR17341), ALK and BRAF V600E IHC were performed. Fourteen AFH cases were identified, which included three cases of intracranial mesenchymal tumours with FET-CREB fusions. PanTRK and ALK positive immunostaining was identified in 9 (64.2%) and 12 (85.7%) cases, respectively. No NTRK or ALK translocations or increased copy number/amplification were identified in all eight cases which had fluorescence in situ hybridisation and/or next generation sequencing for NTRK1-3 and ALK available for assessment. None of the cases expressed BRAF-V600E. Although our study is limited, our report is the first to document PanTRK expression in AFH in the absence of identifiable NTRK1-3 gene alterations.

Preoperative biopsy for retroperitoneal sarcoma (RPS) enables appropriate multidisciplinary treatment planning. A systematic review of literature from 1990 to June 2022 was conducted using the population, intervention, comparison and outcome model to evaluate the local recurrence and overall survival of preoperative biopsy compared to those that had not. Of 3192 studies screened, five retrospective cohort studies were identified. Three reported on biopsy needle tract seeding, with only one study reporting biopsy site recurrence of 2 %. Two found no significant difference in local recurrence and one found higher 5-year local recurrence rates in those who had not been biopsied. Three studies reported overall survival, including one with propensity matching, did not show a difference in overall survival. In conclusion, preoperative core needle biopsy of RPS is not associated with increased local recurrence or adverse survival outcomes.

Currently, there is no robust evidence demonstrating a clear association between Lynch syndrome and non-malignant breast pathology such as adenomyoepithelioma. We report a case of benign breast adenomyoepithelioma, which after recurrence was associated with ductal carcinoma in-situ (DCIS) in a 41-year-old woman with Lynch syndrome, who lacked significant family history of breast or ovarian cancer. Both, the adenomyoepithelioma and DCIS were found to have nuclear loss of MSH2/MSH6 by immunohistochemistry, while germline testing confirmed MSH2 gene mutation. Concordant loss of MSH2 in both lesions in the context of a MSH2 pathogenic variant in this patient with Lynch syndrome illustrates that the benign adenomyoepithelioma behaved as a likely precursor of DCIS. Our report provides a novel perspective that in some patients with Lynch syndrome adenomyoepithelioma may represent a pre-malignant precursor lesion of DCIS.

Our aim was to utilise a 241-gene RNA hybridisation capture sequencing (CaptureSeq) gene panel to identify unexpected fusions in undifferentiated, unclassified or partly classified sarcomas of young individuals (<40 years). The purpose was to determine the utility and yield of a large, targeted fusion panel as a tool for classifying tumours that do not fit typical diagnostic entities at the time of the original diagnosis. RNA hybridisation capture sequencing was performed on 21 archival resection specimens. Successful sequencing was obtained in 12 of 21 samples (57%), two of which (16.6%) harboured translocations. A novel NEAT1::GLI1 fusion, not previously reported in the literature, presented in a young patient with a tumour in the retroperitoneum, which displayed low grade epithelioid cells. The second case, a localised lung metastasis in a young male, demonstrated a EWSR1::NFATC2 translocation. No targeted fusions were identified in the remaining 83.4% (n=10) of cases. Forty-three per cent of the samples failed sequencing as a result of RNA degradation. RNA-based sequencing is an important tool, which helps to redefine the classification of unclassified or partly classified sarcomas of young adults by identifying pathogenic gene fusions in up to 16.6% of the cases. Unfortunately, 43% of the samples underwent significant RNA degradation, falling below the sequencing threshold. As CaptureSeq is not yet available in routine pathology practice, increasing awareness of the yield, failure rate and possible aetiological factors for RNA degradation is fundamental to maximise laboratory procedures to improve RNA integrity, allowing the potential identification of significant gene alterations in solid tumours.

Figure S1. Generation of E2F7 and E2F8 deficient murine keratinocytes and the validation of E2F1 levels in E2F1KO mice.

Figure S2. Adenovirus infection of murine keratinocytes does not alter normal cell responses.

To the Editor, Dedifferentiated liposarcoma (DD-LPS) is as an atypical lipomatous tumour/well differentiated liposarcoma (ALT/WD-LPS) showing progression to high or low-grade sarcoma either in the primary or in the recurrence.1WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. 5th ed. IARC, Lyon2020: 36-41Google Scholar,2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar ALT/WD-LPS and DD-LPS are both characterised by supernumerary ring or giant marker chromosomes, which contain amplified sequences from the 12q14–q15 region with MDM2 being the main driver gene. Other genes within the 12q14–q15 region (i.e., CDK4, HMGA2, SAS, DDIT3, STAT6, etc) are frequently co-amplified which does not imply increased genomic complexity. MDM2 amplification with or without a small number of other numerical or structural abnormalities is seen in WD-LPS, while a complex karyotype is associated with progression to DD-LPS.1WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. 5th ed. IARC, Lyon2020: 36-41Google Scholar, 2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar, 3Sandberg A.A. Updates on the cytogenetics and molecular genetics of bone and soft tissue tumors: liposarcoma.Caner Genet Cytogenet. 2004; 155: 1-24Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar Low-grade DD-LPS (LG-DDL) can show phenotypic diversity, but commonly includes fascicles of spindle cells with mild atypia and mild cellularity mimicking a myofibroblastic tumour. The recognition of pure LG-DDL, in the absence of high-grade dedifferentiation, can be extremely challenging as there can be overlapping morphological features with cellular WD-LPS.1WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. 5th ed. IARC, Lyon2020: 36-41Google Scholar,2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar By using a modified scheme of the Federation Nationale des Centres de Lutte Contre le Cancer (FNCLCC) grading system, Jour et al. demonstrated that grade one LG-DDL is rare, representing 6% of all DD-LPS.4Jour G. Gullet A. Liu M. et al.Prognostic relevance of Federation Nationale des Centres de Lutte Contre le Cancer grade and MDM2 amplification levels in dedifferentiated liposarcoma: a study of 50 cases.Mod Pathol. 2015; 28: 37-47Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar Limited data have shown that LG-DDL has a lower risk of local recurrence and improved overall survival when compared with high-grade DD-LPS;2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar,4Jour G. Gullet A. Liu M. et al.Prognostic relevance of Federation Nationale des Centres de Lutte Contre le Cancer grade and MDM2 amplification levels in dedifferentiated liposarcoma: a study of 50 cases.Mod Pathol. 2015; 28: 37-47Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar, 5Gronchi A. Collini P. Miceli R. et al.Myogenic differentiation and histologic grading are major prognostic determinants in retroperitoneal liposarcoma.Am J Surg Pathol. 2015; 39: 383-393Crossref PubMed Scopus (82) Google Scholar, 6Dantey K. Schoedel K. Yergiyev O. et al.Correlation of histological grade of dedifferentiation with clinical outcome in 55 patients with dedifferentiated liposarcomas.Hum Pathol. 2017; 66: 86-92Crossref PubMed Scopus (17) Google Scholar nonetheless, universal defining criteria for LG-DDL are applied variably across different series.1WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. 5th ed. IARC, Lyon2020: 36-41Google Scholar,2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar Microarray testing by either single nucleotide polymorphism array (SNP array) or array comparative genomic hybridisation (aCGH) allows genome-wide screening for copy number variants (CNVs)7Theisen A. Microarray-based comparative genomic hybridization (aCGH).Nat Educ. 2008; 1: 45Google Scholar and has been widely utilised to characterise the genomic imbalances of ALT/WD-LPS and DD-LPS.1WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. 5th ed. IARC, Lyon2020: 36-41Google Scholar,8Horvai A.E. DeVries S. Roy R. et al.Similarity in genetic alterations between paired well-differentiated and dedifferentiated components of dedifferentiated liposarcoma.Mod Pathol. 2009; 22: 1477-1488Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar, 9Tap W.D. Eilber F.C. Ginther C. et al.Evaluation of well-differentiated/de-differentiated liposarcomas by high-resolution oligonucleotide array-based comparative genomic hybridization.Genes Chromosomes Cancer. 2011; 50: 95-112Crossref PubMed Scopus (80) Google Scholar, 10Crago A.M. Socci N.D. DeCarolis P. et al.Copy number losses define subgroups of dedifferentiated liposarcoma with poor prognosis and genomic instability.Clin Cancer Res. 2012; 18: 1334-1340Crossref PubMed Scopus (59) Google Scholar However, there are only very limited data8Horvai A.E. DeVries S. Roy R. et al.Similarity in genetic alterations between paired well-differentiated and dedifferentiated components of dedifferentiated liposarcoma.Mod Pathol. 2009; 22: 1477-1488Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar addressing the degree of genomic complexity of LG-DDL. In this report we utilised SNP array to assess the degree of CNVs in five cases with either definitive or suspicious features of pure LG-DDL. This study was approved by our local research ethics committee (NSLHD HREC Ref. 1312-417M). Five cases with confirmed MDM2 amplification by fluorescent in situ hybridisation (FISH) were selected for this study. FISH was performed as previously reported.11Vargas A.C. Joy C. Cheah A.L. et al.Lessons learnt from MDM2 fluorescence in-situ hybridisation analysis of 439 mature lipomatous lesions with an emphasis on atypical lipomatous tumour/well-differentiated liposarcoma lacking cytological atypia.Histopathology. 2022; 80: 369-380Crossref PubMed Scopus (4) Google Scholar Three cases (Cases 1–3) were reported as DD-LPS with dedifferentiation consistent with low-grade (referred to as LG-DDL for this study). The following criteria were used to define low-grade dedifferentiation: lack of lipogenic differentiation across >10% of the tumour in at least a low-power (×10 objective) field and presenting as a well-defined area of sharp interface, absence of marked cytological atypia and necrosis, and <5 mitoses/10 high power fields (HPFs).2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar,4Jour G. Gullet A. Liu M. et al.Prognostic relevance of Federation Nationale des Centres de Lutte Contre le Cancer grade and MDM2 amplification levels in dedifferentiated liposarcoma: a study of 50 cases.Mod Pathol. 2015; 28: 37-47Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar, 5Gronchi A. Collini P. Miceli R. et al.Myogenic differentiation and histologic grading are major prognostic determinants in retroperitoneal liposarcoma.Am J Surg Pathol. 2015; 39: 383-393Crossref PubMed Scopus (82) Google Scholar, 6Dantey K. Schoedel K. Yergiyev O. et al.Correlation of histological grade of dedifferentiation with clinical outcome in 55 patients with dedifferentiated liposarcomas.Hum Pathol. 2017; 66: 86-92Crossref PubMed Scopus (17) Google Scholar These cases were equivalent to grade 1 of the modified FNCLCC grading system.4Jour G. Gullet A. Liu M. et al.Prognostic relevance of Federation Nationale des Centres de Lutte Contre le Cancer grade and MDM2 amplification levels in dedifferentiated liposarcoma: a study of 50 cases.Mod Pathol. 2015; 28: 37-47Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar DNA was extracted from 4 μm unstained formalin-fixed, paraffin-embedded (FFPE) tissue sections using the QIAgen GeneRead FFPE DNA Kit (Qiagen, Australia). DNA was concentrated using the Zymo DNA Clean & Concentrator-25 kit (ThermoFisher, Australia) and quantified using Qubit and the dsDNA Quantitation, Broad Range kit (ThermoFisher Scientific). Genome-wide SNP array using Illumina Infinium GSAMD v3.0 Psych v1.1 (Illumina, USA) was performed at a resolution of 10 Mb for copy number abnormalities and regions of copy-neutral loss of heterozygosity. Analytical limit of detection for MDM2 amplification was 5 copies in a diploid sample with 20% neoplastic cell content. This was analysed by NxClinical software v6.0 (Bionano, USA; genome build GRCh37/hg19). Three cases (Cases 1–3) of LG-DDL and two cases of ALT suspicious but not definitive for LG-DDL (Cases 4 and 5) were subjected to SNP array (Fig. 1, Fig. 2, Table 1). Morphologically, Case 1 (primary DD-LPS) displayed a well circumscribed discrete myxoid nodule with ‘chicken-wire’ vasculature resembling myxoid liposarcoma (ML) in a background of WD-LPS. This case harboured DDIT3 co-amplification by FISH. Case 2, presenting as pulmonary metastasis in a patient with history of abdominal DD-LPS, displayed prominent myxoid morphology and homologous dedifferentiation. Occasional scattered pleomorphic cells were present, and although this may represent a high-grade dedifferentiated component, pleomorphic cells were not confluent, representing the minority of the cell population, and were absent in the block submitted for molecular analysis. Case 3 (primary DD-LPS) was a paratesticular mass almost entirely (>70%) comprised of whorls of spindle cells and palisade formation. Cases 4 and 5 were recurrent ALTs, as located in the extremities, with features suspicious but insufficient for LG-DDL. Case 4 showed ML-like areas and DDIT3 co-amplification but lacked circumscription of the myxoid areas, which intermingled with the lipomatous component. Case 5 displayed numerous hyperchromatic atypical stromal cells in cellular fibroconnective septae. On CT scan, this case was highly suspicious for DD-LPS. Myoid differentiation (based on IHC expression of SMA and desmin) was not identified in any of the cases.Fig. 2Low-grade dedifferentiated liposarcoma (LG-DDL), Case 3, and atypical lipomatous tumour (ALT), Cases 4 and 5. Case 3 (A,B) was comprised of whorls of spindle cells of myofibroblastic appearance and palisade formation. Case 4 (D) and Case 5 (E) showed ALTs with confluent myxoid areas alternating with a lipomatous component (D) or numerous hyperchromatic atypical stromal cells in cellular fibroconnective septae (E). SNP microarray of Case 1 (C) and Case 4 (F) demonstrated 12q14–q15 amplification in a background of a simple karyotype. Case 4 (F) also showed 18q gain.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Table 1Summary of five cases with findings of array comparative genomic hybridisationCase IDDxGender, age, siteSizeCNVs other than MDM2 amplificationFollow-upCase 1 DD-LPSM 75, paratesticular mass50 mmHigh gain (>4 copies) of 2q34q36; high gain (>4 copies) of 6q21 and 6q22; loss of 7q11.23q36.1; gains of 4q28 and 13q331 year, developed lung adenocarcinomaCase 2 DD-LPSM 77, lung metastasis (primary abdominal)20 mm and 10 mm nodulesLoss 1p31.3–p12; gain of 1q21.3–q42.2; trisomy 8; whole arm loss of 10p; whole arm loss of 11p; high gain at 11q14; loss at 11q14.1–q25; loss 15q11.2–q21.3; Y loss1 year, developed further metastatic disease to distant soft tissueCase 3 DD-LPSM 84, left paratesticular mass35 mmNil3 year (current), no recurrence/metastasisCase 4 ALTF 59, recurrent left arm75 mmHigh gain (>4 copies) of 18q12.3q22.13 year (current), no recurrence/metastasisCase 5 ALTM 69, recurrent right thigh mass125 mmAmplification of 1q23-q24N/A (recent case)ALT, atypical lipomatous tumour; CNV, copy number variation; DD-LPS, dedifferentiated liposarcoma; Dx, diagnosis; F, female; M, male; N/A, not available. Open table in a new tab ALT, atypical lipomatous tumour; CNV, copy number variation; DD-LPS, dedifferentiated liposarcoma; Dx, diagnosis; F, female; M, male; N/A, not available. SNP array demonstrated that both cases of ALT with histological features suspicious but not definitive for LG-DDL (Cases 4 and 5) and one LG-DDL case (Case 3) displayed, apart from MDM2 amplification, a simple karyotype with 18q12 gain and 1q23–q24 co-amplification, presenting each in an individual sample (Table 1). None of these three cases developed recurrence or metastasis on follow-up, reflecting the genomic changes underlying typical ALT/WD-LPS. On the other hand, the two remaining LG-DDLs (Cases 1 and 2) harboured a complex karyotype associated with gains of 2q34q36, 6q21–22, 4q28 and 13q33, and loss of 7q11.23 (Case 1) or gains of 1q21.3–q42.2 and 11q14 and loss of 1p31.3–p12, 11q14.1–q25, 15q11.2–q21, whole arm of 10 p and 11 p and trisomy 8 (Case 2; Table 1). Horvai et al.8Horvai A.E. DeVries S. Roy R. et al.Similarity in genetic alterations between paired well-differentiated and dedifferentiated components of dedifferentiated liposarcoma.Mod Pathol. 2009; 22: 1477-1488Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar and others1WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. 5th ed. IARC, Lyon2020: 36-41Google Scholar, 2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar, 3Sandberg A.A. Updates on the cytogenetics and molecular genetics of bone and soft tissue tumors: liposarcoma.Caner Genet Cytogenet. 2004; 155: 1-24Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar,9Tap W.D. Eilber F.C. Ginther C. et al.Evaluation of well-differentiated/de-differentiated liposarcomas by high-resolution oligonucleotide array-based comparative genomic hybridization.Genes Chromosomes Cancer. 2011; 50: 95-112Crossref PubMed Scopus (80) Google Scholar,10Crago A.M. Socci N.D. DeCarolis P. et al.Copy number losses define subgroups of dedifferentiated liposarcoma with poor prognosis and genomic instability.Clin Cancer Res. 2012; 18: 1334-1340Crossref PubMed Scopus (59) Google Scholar,12Beird H.C. Wu C.C. Ingram D.R. et al.Genomic profiling of dedifferentiated liposarcoma compared to matched well-differentiated liposarcoma reveals higher genomic complexity and a common origin.Cold Spring Harb Mol Case Stud. 2018; 4: a002386Crossref PubMed Scopus (45) Google Scholar have demonstrated that no genetic changes uniformly distinguish well differentiated and dedifferentiated components of DD-LPS within the same tumour and that individual genetic abnormalities are non-repetitive. Reported CNVs of DD-LPS include amplifications in 1p31–32, 1q21–24, 3q13.2–q25, 6q23–24, 12q13.3 and 12q24; gains at 6q14.1, 6q23.2, 10q21.1, 12q14.1–14, 14q, 17q21, 19q13.2 and 20q11; and losses at 3p14–21, 6p, 6q, 9p22–24, 10p15, 11q23–24, 11p, 13q, 17p11 and 19q13.1WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. 5th ed. IARC, Lyon2020: 36-41Google Scholar, 2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar, 3Sandberg A.A. Updates on the cytogenetics and molecular genetics of bone and soft tissue tumors: liposarcoma.Caner Genet Cytogenet. 2004; 155: 1-24Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar,8Horvai A.E. DeVries S. Roy R. et al.Similarity in genetic alterations between paired well-differentiated and dedifferentiated components of dedifferentiated liposarcoma.Mod Pathol. 2009; 22: 1477-1488Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar, 9Tap W.D. Eilber F.C. Ginther C. et al.Evaluation of well-differentiated/de-differentiated liposarcomas by high-resolution oligonucleotide array-based comparative genomic hybridization.Genes Chromosomes Cancer. 2011; 50: 95-112Crossref PubMed Scopus (80) Google Scholar, 10Crago A.M. Socci N.D. DeCarolis P. et al.Copy number losses define subgroups of dedifferentiated liposarcoma with poor prognosis and genomic instability.Clin Cancer Res. 2012; 18: 1334-1340Crossref PubMed Scopus (59) Google Scholar,12Beird H.C. Wu C.C. Ingram D.R. et al.Genomic profiling of dedifferentiated liposarcoma compared to matched well-differentiated liposarcoma reveals higher genomic complexity and a common origin.Cold Spring Harb Mol Case Stud. 2018; 4: a002386Crossref PubMed Scopus (45) Google Scholar Although we identified some of the chromosomal aberrations previously reported (amp 1q23–24; gain at 6q21–22; and losses at 10p, 11p and 11q14.1–q25), additional CNVs were present in our cases: gains at 1q21.3–q42.2, 2q34–36, 4q28, 11q14, 13q33 and 18q12; loss of 1p31.3–p12, 7q11; whole arm loss of 10p, 15q11.2–q21.3 and trisomy 8. Although Horvai et al.8Horvai A.E. DeVries S. Roy R. et al.Similarity in genetic alterations between paired well-differentiated and dedifferentiated components of dedifferentiated liposarcoma.Mod Pathol. 2009; 22: 1477-1488Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar analysed LG-DDL by using aCGH as part of a larger series of cases, comparative analysis of genomic alterations presenting in low-versus high-grade DD-LPS was not documented in that study. This limited analysis has demonstrated that there is a high concordance between the findings of microarray testing and the morphological features of ALT/DD-LPS. For two cases of ALT with suspicious but not definitive features of DD-LPS, SNP array showed absence of a complex karyotype as expected in conventional type WD-LPS/ALT. Only a few additional genomic alterations were identified in these cases including DDIT3 co-amplification, which on its own it is not indicative of underlying complex karyotype. Concordantly, SNP array identified a complex genome in two of three samples with unequivocal dedifferentiation. Altogether, SNP array was predictive of the morphological features of ALT/WD-LPS with or without dedifferentiation in four of five cases (80%) with only one case of DD-LPS (Case 3) demonstrating absence of CNVs by the assay utilised, reflecting the genome of conventional ALT/WD-LPS. That case showed mild cytological atypia, absence of necrosis and low numbers of mitoses (1 per 10 HPFs), in the absence of a lipogenic component across the entire lesion (Fig. 2A,B). Therefore, it is possible that there is a subset of true LG-DDL with a genomic signature similar to conventional ALT/WD-LPS. An important observation of our study is that chromosomal imbalances identified in two of three LG-DDL (Cases 1 and 2) were those of a complex karyotype sarcoma, and although these are non-recurrent predictive alterations, they are within the spectrum of CNVs expected in high-grade DD-LPS.1WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. 5th ed. IARC, Lyon2020: 36-41Google Scholar, 2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar, 3Sandberg A.A. Updates on the cytogenetics and molecular genetics of bone and soft tissue tumors: liposarcoma.Caner Genet Cytogenet. 2004; 155: 1-24Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar,8Horvai A.E. DeVries S. Roy R. et al.Similarity in genetic alterations between paired well-differentiated and dedifferentiated components of dedifferentiated liposarcoma.Mod Pathol. 2009; 22: 1477-1488Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar, 9Tap W.D. Eilber F.C. Ginther C. et al.Evaluation of well-differentiated/de-differentiated liposarcomas by high-resolution oligonucleotide array-based comparative genomic hybridization.Genes Chromosomes Cancer. 2011; 50: 95-112Crossref PubMed Scopus (80) Google Scholar, 10Crago A.M. Socci N.D. DeCarolis P. et al.Copy number losses define subgroups of dedifferentiated liposarcoma with poor prognosis and genomic instability.Clin Cancer Res. 2012; 18: 1334-1340Crossref PubMed Scopus (59) Google Scholar,12Beird H.C. Wu C.C. Ingram D.R. et al.Genomic profiling of dedifferentiated liposarcoma compared to matched well-differentiated liposarcoma reveals higher genomic complexity and a common origin.Cold Spring Harb Mol Case Stud. 2018; 4: a002386Crossref PubMed Scopus (45) Google Scholar These findings are in line with previous observations that genetic abnormalities associated with dedifferentiation/progression may precede phenotypic changes, which would support a biology of LG-DDL similar to that of high-grade DD-LPS. Nonetheless, a similar degree of underlying genomic complexity would not explain the reported superior outcome of LG-DDL when compared with its high-grade counterpart.4Jour G. Gullet A. Liu M. et al.Prognostic relevance of Federation Nationale des Centres de Lutte Contre le Cancer grade and MDM2 amplification levels in dedifferentiated liposarcoma: a study of 50 cases.Mod Pathol. 2015; 28: 37-47Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar, 5Gronchi A. Collini P. Miceli R. et al.Myogenic differentiation and histologic grading are major prognostic determinants in retroperitoneal liposarcoma.Am J Surg Pathol. 2015; 39: 383-393Crossref PubMed Scopus (82) Google Scholar, 6Dantey K. Schoedel K. Yergiyev O. et al.Correlation of histological grade of dedifferentiation with clinical outcome in 55 patients with dedifferentiated liposarcomas.Hum Pathol. 2017; 66: 86-92Crossref PubMed Scopus (17) Google Scholar It is important to emphasise that diagnostic criteria for LG-DDL have been applied variably and homogeneous cohorts with detailed follow-up and combined molecular data are lacking.2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar In a recent comprehensive review, Kilpatrick2Kilpatrick S.E. Dedifferentiated liposarcoma: a comprehensive historical review with proposed evidence-based guidelines regarding a diagnosis in need of further clarification.Adv Anat Pathol. 2021; 28: 426-438PubMed Google Scholar identified that the reported survival and prognostic data of pure LG-DDL are inconsistent, partly due to the fact that most cases have displayed admixed high-grade component and their recurrent/metastatic deposits have been unavailable for further review. In summary, microarray testing can be helpful to assess the genomic diversity of LG-DDL, which is a very challenging diagnosis that subspecialised soft tissue pathologists often struggle with, and with resultant inter-variability discordance. Our limited study showed that assessment of genomic complexity using SNP microarray in ALT/WD-LPS can act as a complementary ancillary tool in the classification of cases with equivocal areas for low-grade dedifferentiation. Knowledge of the underlying karyotype of difficult cases may potentially impact immediate clinical management and long-term surveillance. Absence of CNV by microarray can potentially be utilised to support the diagnosis of ALT/WD-LPS without dedifferentiation in cases with equivocal morphology, but it can also be suggestive of a clinical behaviour more similar to ALT/WD-LPS in cases with unequivocal de-differentiation. The authors state that there are no conflicts of interest to disclose.

Figure S3. Cytotoxic responses to doxorubicin selectively enhanced in E2F7-deficient murine keratinocytes.

Supplementary Table S1: Differentially expressed genes (List A and List B combined) identified as E2F7-dependent cytotoxic sensitivity genes

Figure S5. SK1-I did not enhance doxorubicin sensitivity in KJDSV40 cells in vitro.

Figure S4. Validation of siRNA directed against E2F7 and E2F1 mRNA expression level in SCC25 cells in which E2F7 had been silenced by siRNA.

Figure S6. Inhibition of Sphk1 sensitizes FaDu cells to the cytotoxic actions of doxorubicin in vitro and in vivo.

The file contains figure legends for 6 supplementary figures

Introduction: Proliferative fasciitis (PF) and proliferative myositis (PM) are benign soft tissue neoplasms occurring in the subcutaneous tissue (PF) or skeletal muscle (PM).1 Gene FOS rearrangements and immunohistochemical (IHC) expression have been recently identified in PF/PM in a single study.2 Aim: To explore the performance of the c-FOS antibody in PF/MF and in a range of soft tissue sarcomas. Material and methods: IHC for c-FOS using the polyclonal antibody ABE457 was performed on full sections of PF (n=5), PM (n=2), florid scars (n=6) and on a cohort of 275 samples from various sarcoma types derived from tissue microarrays (TMAs). Result: All cases of PF/PM (100%) demonstrated ganglion-like cells and/or myofibroblastic cells positive for c-FOS IHC. From the sarcoma cohort, only 3 (1%) of 275 cases displayed c-FOS expression while none of the scars displayed immunoreactivity with the antibody. Conclusion: Our study indicates that c-FOS positive stain can support the diagnosis of PF/PM in the appropriate clinical and morphological context. Negative c-FOS stain was identified in florid scars and in 99% of the sarcoma samples. Nonetheless, caution is warranted as our cohort is limited and further validation is required. In addition, 1% of soft tissue sarcomas also expressed C-FOS IHC. References 1. WHO Classification of Tumours Editorial Board. World Health Organization Classification of Tumours. Soft Tissue and Bone Tumours. Lyon: IARC Press, 2020. 2. Makise N, Mori T, Motoi T, et al. Recurrent FOS rearrangement in proliferative fasciitis/proliferative myositis. Mod Pathol 2021; 34: 942–50.

Background T-cell-rich angiomatoid polypoid pseudolymphoma (TRAPP) and inflammatory lobular hemangioma (ILH) encompass a spectrum of cutaneous vascular lesions in which a prominent lymphoplasmacytic component may impart a pattern highly reminiscent of low-grade cutaneous lymphoma (pseudolymphoma). Epithelioid hemangioma, including its most common variant angiolymphoid hyperplasia with eosinophilia (ALHE), is a distinct entity associated with FOS and/or FOSB expression detected by immunohistochemistry (IHC). These entities can show significant morphological overlap. Methods We performed IHC for FOSB, FOS, and lymphoid markers in a series of TRAPP/ILH and ALHE. Results We identified 13 cases of ILH/TRAPP, which showed a predominance in CD8(+) T-cells (CD8>CD4: 11/13) while FOSB and FOS were expressed in 36% (4/11) and 27% (3/11) of cases, respectively. ALHE (n = 9) showed a predominance in CD4(+) T-cell (67%) with FOSB and FOS co-expression in 78% (seven of nine) of the cases. Conclusion We showed, based on FOS and/or FOSB immunohistochemical expression, that there is a possible link between ILH/TRAPP and epithelioid hemangioma/ALHE. The use of FOS and FOSB IHC in the routine diagnostic setting of cutaneous vascular lesions will help to redefine cases of ILH/TRAPP as a subset of these may represent inflammatory variants of epithelioid hemangioma.

ERG overexpression has been linked to acute myeloid leukemia/myeloid sarcoma (MS). The aim of our study was to identify the frequency of ERG immunohistochemical (IHC) expression in MS (n = 21), blastic plasmacytoid dendritic cell neoplasms (BPDCNs; n = 8), extramedullary hematopoiesis (EMH: n = 9), normal and pathological bone marrow trephine biopsies (BM-TBs, n = 18), and the marrow component of adrenal myelolipomas (n = 15). ERG-positive and ERG-negative immunostains were identified in 68.4% and 31.5% of patients with MS, respectively (2-3+, 20% to >90% of cells), while all BPDCNs were negative. ERG + MS cases were over-represented in those of myeloid differentiation when compared with those of pure monocytic/monoblastic differentiation, which were ERG-negative (P=<0.001). ERG was expressed in immature myeloid cells in 100% of cases of EMH, BM-TBs, and adrenal myelolipomas (n = 42), resulting in a sensitivity of 100% in this setting. Negative ERG immunostaining was also 100% sensitive in discriminating cells of erythroid lineage, mature lymphocytes, and reactive or neoplastic plasma cells. Variable IHC expression occurred in megakaryocytes and neutrophils. In summary, we confirmed a high frequency of ERG expression in MS and identified ubiquitous expression in non-neoplastic immature myeloid lineage cells. We believe that ERG can be of diagnostic utility to identify neoplastic and reactive myeloid infiltrates in peripheral tissues and possibly as an ancillary marker to exclude the diagnosis of BPDCNs when positive. However, ERG must be used in an antibody panel, as expression is not limited to myeloid cells.

Introduction: Epithelioid hemangioma is a benign vascular neoplasm associated with FOS and/or FOSB protein overexpression detected by immunohistochemistry (IHC). Methods: The aim of our study was to determine the co-expression or independent IHC expression of FOS and FOSB in a cohort of epithelioid hemangiomas. We also included two cohorts of other vascular lesions: papillary endothelial hyperplasia and lobular capillary hemangioma / pyogenic granuloma. Results: We identified 50 cases of epithelioid hemangioma, 84% of which were cutaneous and the remaining involved other anatomic locations. Over two thirds of all cases expressed FOSB (68%; 34/50) while FOS immunoreactivity was identified in 46% of all cases. Co-expression of FOSB and FOS occurred in 37% of cases while 76% of all cases stained for at least one of the antibodies. Fifty-eight percent (n = 14/24) and 33% (8/24) of all cases of papillary endothelial hyperplasia expressed FOS and FOSB, respectively. Thirty-two per cent of lobular capillary hemangiomas (n = 8/25) were positive for either FOS or FOSB. Conclusion: In summary, we present the largest cohort of epithelioid hemangiomas assessed with both FOS and FOSB and demonstrated that the use of both antibodies increases the detection rate of these proliferations by 10%. Nonetheless, the use of thresholds may not be appropriate, as only a subset of lesional endothelial cells label with FOS/FOSB. Over half of all cases of papillary endothelial hyperplasia and a third of lobular capillary hemangiomas also displayed immunoreactivity with FOS and/or FOSB.

The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Data sharing not applicable to this article as no datasets were generated or analysed during the current study

ABSTRACTCancer cells invoke phenotypic plasticity programs to drive disease progression and evade chemotherapeutic insults, yet until now there have been no validated clinical therapies targeting this process. Here, we identify a phenotypic plasticity signature associated with poor survival in basal/triple-negative breast cancer, in which androgen signalling is prominent. We establish that anti-androgen therapies block cancer stem cell function and prevent chemotherapy-induced emergence of new cancer stem cells. In particular, the anti-androgen agent seviteronel synergizes with chemotherapy to improve chemotherapeutic inhibition of primary and metastatic tumour growth and prevent the emergence of chemotherapy-resistant disease. We validate cytoplasmic AR expression as a clinical phenotypic plasticity biomarker that predicts poor survival and poor response to chemotherapy, and positive response to seviteronel plus chemotherapy. This new targeted combination therapy validates modulating phenotypic plasticity as an effective strategy to prevent and treat chemotherapy-resistant cancers with transformative clinical potential.STATEMENT OF SIGNIFICANCEThere are currently no curative therapies for patients with chemotherapy-resistant cancer. We demonstrate that modulating phenotypic plasticity prevents the emergence of chemotherapy-resistant disease in triple-negative breast cancer. This represents the first known validated clinical therapy leveraging phenotypic plasticity. Moreover, we identify a highly effective anti-androgen drug and a biomarker to select and treat patients best-suited to this new therapy. A clinical trial is underway (NCT04947189).SUMMARY SENTENCEBlocking phenotypic plasticity is an effective targeted therapeutic strategy to treat cance

Epithelioid fibrous histiocytoma (EFH) is a cutaneous neoplasm driven by translocations of the anaplastic lymphoma kinase (ALK) gene, which can be demonstrated by immunohistochemical (IHC) analysis. We analyzed the performance of two ALK clones, D5F3 and ALK1, in a cohort of EFHs and described the range of architectural variation of these lesions. TFE3 IHC was performed in ALK-negative EFHs. We identified 21 cases of EFH, 76.2% of which showed an exophytic appearance and 19% displayed flat architecture. A well-developed epidermal collarette was present in 48% of all cases with just more than a third of all the exophytic lesions presenting as dermal-based nodules. ALK D5F3 expression was identified in 76.2% (16/21) of all cases, but only 68.8% were concordantly positive with the ALK1 clone, indicative of a false-negative stain with ALK1 in 31.2% of the cases. For the subset of cases showing positivity for the ALK1 clone, a marked decrease in the percentage of immunolabelled cells was identified when compared with D5F3 (5-50% vs. 100%, respectively). Five cases (23.8%) did not demonstrate ALK expression for either clone, with 3 of those cases showing nuclear positivity for TFE3 IHC and the remaining 2 cases being double negative (ALK-/TFE3-). In summary, we identified that the prototypically described exophytic appearance with epidermal collarette is present in only less than half of the cases. We also demonstrated that the ALK1 antibody is suboptimal in EFH and should not be utilized in this setting. A subset of ALK-negative cases express TFE3, but double-negative cases occur. (C) 2021 Published by Elsevier Inc.