D. Chas Mangham

Brachyury expression in extra-axial skeletal and soft tissue chordomas: A marker that distinguishes chordoma from mixed tumor/myoepithelioma/parachordoma in soft tissue

Axial chordoma represents approximately 1% of malignant bone tumors. This tumor expresses cytokeratins, specifically cytokeratin 19, and commonly S100. More recently brachyury, a transcription factor important in mesodermal differentiation, including notochord development, has been detected by immunohistochemistry in axial chordomas and hemangioblastomas but not chondrosarcomas or other neoplasms. In this report, we describe 10 cases (6 men, 4 women: age 18 to 68 y; mean 44.6) of extra-axial tumors, 8 in bone and 2 in soft tissue, with morphologic and immunohistochemical features identical to those of axial chordoma. Imaging excluded metastases from axial chordoma. Three tumors occurred in the tibia, the others in the rib, metatarsal, ulna, femur, pubis: 2 intracortical, 6 intramedullary. Both soft tissue brachyury-positive tumors, one involving the thumb the other the wrist, were sited in the juxta-articular region. Seven of the tumors were widely excised and these patients are disease-free but of the 3 tumors that recurred, 1 was curetted, 1 was marginally excised, and 1 had a pathologic fracture on presentation. Metastases have not occurred in any of the patients. We also confirm the expression of brachyury in hemangioblastomas, and for the first time demonstrates its expression in spermatogonia and testicular germ cell tumors by immunohistochemistry. Brachyury was not detected in a wide range of tumors including carcinomas, lymphomas, and sarcomas. In conclusion, we describe the first series of extra-axial skeletal chordomas bringing the total number of such cases reported in the literature to 11, and present the first report of 2 soft tissue chordomas as defined by brachyury expression.

A gene expression signature associated with metastatic outcome in human leiomyosarcomas.

Metastasis is a major factor associated with poor prognosis in cancer, but little is known of its molecular mechanisms. Although the clinical behavior of soft tissue sarcomas is highly variable, few reliable determinants of outcome have been identified. New markers that predict clinical outcome, in particular the ability of primary tumors to develop metastatic tumors, are urgently needed. Here, we have chosen leiomyosarcoma as a model for examining the relationship between gene expression profile and the development of metastasis in soft tissue sarcomas. Using cDNA microarray, we have identified a gene expression signature associated with metastasis in sarcoma that allowed prediction of the future development of metastases of primary tumors (Kaplan-Meier analysis P = 0.001). Our finding may aid the tailoring of therapy for individual sarcoma patients, where the aggressiveness of treatment is affected by the predicted outcome of disease.

Clinical outcomes of deep atypical lipomas (well‐differentiated lipoma‐like liposarcomas) of the extremities

Aim:  Controversy exists with regard to the nomenclature, treatment and outcome of a group of well‐differentiated lipomatous tumours sometimes labelled as atypical lipomas. The purpose of the present paper is to attempt to clarify these controversies by reporting our experience with this lesion.

Chordoma periphericum: a case report.

The authors describe a tumor that had the histologic and ultrastructural features and immunohistochemical profile of an axial chordoma, but arose in the distal ulna. A skeletal survey failed to show any other site of involvement. The tumor was resected, and the patient remains free of disease 2½ years later. Rare tumors with the histologic features of chordoma have been reported in appendicular locations. Chordoma periphericum, a tumor that has the potential to metastasize, needs to be distinguished from parachordoma because no classic parachordoma has been reported to disseminate.

Rarely metastasizing soft tissue tumours.

Soft tissue tumours that rarely metastasize have been afforded their own subcategory in recent WHO classifications. This review discusses the nature of these tumours and the difficulty in constructing usefully simple classifications for heterogeneous and complex groups of tumours. We also highlight the specific rarely metastasizing soft tissue tumours that have been recently added to the WHO classification (phosphaturic mesenchymal tumour, pseudomyogenic haemangioendothelioma) and those entities where there have been recent important defining genetic discoveries (myxoinflammatory fibroblastic sarcoma, solitary fibrous tumour, myoepitheliomas).

FN1‐EGF gene fusions are recurrent in calcifying aponeurotic fibroma

Calcifying aponeurotic fibroma (CAF) is a soft tissue neoplasm with a predilection for the hands and feet in children and adolescents. Its molecular basis is unknown. We used chromosome banding analysis, fluorescence in situ hybridization (FISH), mRNA sequencing (RNA‐seq), RT‐PCR, and immunohistochemistry to characterize a series of CAFs. An insertion ins(2;4)(q35;q25q?) was identified in the index case. Fusion of the FN1 and EGF genes, mapping to the breakpoint regions on chromosomes 2 and 4, respectively, was detected by RNA‐seq and confirmed by RT‐PCR in the index case and two additional cases. FISH on five additional tumours identified FN1–EGF fusions in all cases. CAFs analysed by RT‐PCR showed that FN1 exon 23, 27 or 42 was fused to EGF exon 17 or 19. High‐level expression of the entire FN1 gene in CAF suggests that strong FN1 promoter activity drives inappropriate expression of the biologically active portion of EGF, which was detected immunohistochemically in 8/9 cases. The FN1–EGF fusion, which has not been observed in any other neoplasm, appears to be the main driver mutation in CAF. Although further functional studies are required to understand the exact pathogenesis of CAF, the composition of the chimera suggests an autocrine/paracrine mechanism of transformation. Copyright

Molecular pathology of bone tumours: diagnostic implications.

Alongside histomorphology and immunohistochemistry, molecular pathology is now established as one of the cornerstones in the tissue diagnosis of bone tumours. We describe the principal molecular pathological techniques employed, and each of the bone tumour entities where their identified characteristic molecular pathological changes can be detected to support and confirm the suspected histological diagnosis. Tumours discussed include fibrous dysplasia, classical and subtype osteosarcomas, central and surface cartilaginous tumours, Ewings sarcoma, vascular tumours, aneurysmal bone cyst, chordoma, myoepithelioma, and angiomatoid fibrous histiocytoma. This is a rapidly evolving field with discoveries occurring every few months, and some of the newer entities (the Ewings‐like sarcomas), which are principally identified by their molecular pathology characteristics, are discussed.

Annual Review Issue: Soft Tissue Tumour Pathology

There have been remarkable advances in soft tissue tumour pathology over the 8 years since the inaugural Annual Review Issue in Histopathology, which was also devoted to this challenging area of diagnostic pathology. Not only have many new ‘entities’ been described, but the clinical armamentarium of diagnostic immunohistochemical markers continues to expand, in part owing to the introduction of lineage-restricted transcription factors, as well as the application of gene expression profiling to the challenge of discriminating among histologically similar tumour types. Furthermore, genetic alterations underlying the pathogenesis of soft tissue tumours continue to be elucidated. In most such instances, the genetic findings have served to support our existing histologic classification. However, in some circumstances, discoveries of new mutations have illuminated previously obscure distinctions between sarcomas within a particular histologic class. With the advent of targeted therapies directed against molecular alterations in sarcomas, accurate histologic classification remains of critical importance, and for some sarcoma types, predictive genomic testing has become part of clinical practice. As guest editors of this Annual Review Issue, we have invited a group of renowned experts to update some of the most interesting topics in this diverse field of human neoplasia. In the first article in this issue, Christopher Fletcher provides an overview of the important changes in the classification of soft tissue tumours from the 2002 World Health Organization classification introduced recently in the 2013 WHO classification. This is followed by a review of the evolution of ‘fibrosarcoma’ by Andrew Folpe, including both historical context and our contemporary understanding with the aid of cytogenetics and molecular genetics. Cristina Antonescu then provides an update of round cell sarcomas, illustrating the power of genomic analysis to identify new tumour types previously buried within the confusing ‘wastebasket’ of (non-Ewing) undifferentiated round cell sarcomas. Paolo Dei Tos covers the groups of tumours classified as liposarcomas, emphasizing the integration of immunohistochemistry and molecular genetics with conventional histologic examination in differential diagnosis. The diagnosis and treatment of gastrointestinal stromal tumours (GISTs) have evolved considerably over the past 15 years since the initial discovery of activating mutations in the tyrosine kinase receptor gene KIT; Leona Doyle and Jason Hornick provide an overview of the pathogenesis and treatment of these tumours, focusing on the recently discovered class of GISTs characterized by dysfunction of the succinate dehydrogenase enzyme complex. Surgical pathologists play a critical role in identifying familial cancer predisposition syndromes. Cheryl Coffin and colleagues review the syndromes associated with soft tissue tumours, focusing on how pathologists can recognise and help diagnose patients affected by such disorders. This is followed by an overview of the conceptually challenging area of rarely metastasising (‘intermediate biologic potential’) soft tissue tumours, which includes diverse and distinctive tumour types, by Chas Mangham and Lars-Gunnar Kindblom; the histologic and molecular genetic features of several of these tumours have only recently been properly characterised. Immunohistochemistry continues to hold a central position in soft tissue tumour diagnosis; Markku Miettinen reviews some of the most important immunohistochemical markers, which are indispensable for the surgical pathologist. The last four reviews focus on the molecular genetics of soft tissue tumours. Alex Lazar and colleagues discuss the key roles of the pathologist in identifying appropriate patients for new targeted therapies, both in terms of proper diagnosis and molecular genetic characterisation of sarcomas. Soft tissue (and bone) tumours with EWSR1 gene rearrangements include an ever-expanding, clinically and pathologically diverse list of lesions. This interesting group of tumours is reviewed by Cyril Fisher. The final two articles emphasise new techniques, in particular massively parallel (‘next generation’) sequencing. Fredrik Mertens and Johnbosco Tayebwa provide an update on how such approaches can be applied to gene fusion discovery; Matt van de Rijn and colleagues discuss such forms of molecular analysis on paraffinembedded tissue. We trust the readers of Histopathology will find this diverse set of excellent review articles helpful and informative, both for improving clinical practice in diagnostic surgical pathology and understanding the evolving diagnostic and therapeutic roles of molecular genetic analysis for soft tissue tumours.

RT-PCR for the detection of translocations in bone and soft tissue tumours in formalin-fixed paraffin-embedded tissues

This chapter outlines the methodology for the detection of mesenchymal-tumour-specific translocations in formalin-fixed paraffin-embedded tissue (FFPET) using the reverse transcriptase-polymerase chain reaction (RT-PCR).It includes the design of appropriate primer pairs and the necessary pretreatment of the FFPET sections to give the maximum yield of analyzable RNA, in terms of both quantity and quality.

Identification of FBXL4 as a Metastasis Associated Gene in Prostate Cancer

Prostate cancer is the most common cancer among western men, with a significant mortality and morbidity reported for advanced metastatic disease. Current understanding of metastatic disease is limited due to difficulty of sampling as prostate cancer mainly metastasizes to bone. By analysing prostate cancer bone metastases using high density microarrays, we found a common genomic copy number loss at 6q16.1–16.2, containing the FBXL4 gene, which was confirmed in larger series of bone metastases by fluorescence in situ hybridisation (FISH). Loss of FBXL4 was also detected in primary tumours and it was highly associated with prognostic factors including high Gleason score, clinical stage, prostate-specific antigen (PSA) and extent of disease, as well as poor patient survival, suggesting that FBXL4 loss contributes to prostate cancer progression. We also demonstrated that FBXL4 deletion is detectable in circulating tumour cells (CTCs), making it a potential prognostic biomarker by ‘liquid biopsy’. In vitro analysis showed that FBXL4 plays a role in regulating the migration and invasion of prostate cancer cells. FBXL4 potentially controls cancer metastasis through regulation of ERLEC1 levels. Therefore, FBXL4 could be a potential novel prostate cancer suppressor gene, which may prevent cancer progression and metastasis through controlling cell invasion.