Immunohistochemistry in the diagnosis of soft tissue tumours

Immunohistochemistry is particularly important in the field of soft tissue tumours because of their variety and the frequent difficulty of diagnosis. The first part of this paper discusses useful or new antibodies, together with others that are no longer of use. The second part is devoted to the role of immunohistochemistry in the diagnosis of soft tissue tumours: identification of some rare or atypical benign lesions, identification of non-mesenchymal malignant tumours, and classification of sarcomas. The respective roles of immunohistochemistry and molecular biology are underlined.     

Myxoid tumours of soft tissue

Myxoid tumours of soft tissue encompass a heterogeneous group of lesions characterized by a marked abundance of extracellular mucoid (myxoid) matrix. This group of tumours demonstrate significant variability in their biological behaviour thus including tumours which are entirely harmless, tumours with a tendency to recur locally but not metastasize, and malignant tumours. There appears to be a considerable degree of overlap clinically and morphologically between the various tumour types in this group, generating potential diagnostic problems for the clinician and pathologist alike. While diligent microscopy remains the basis of diagnostic pathology, the continuous developments and refinements within the fields of immunohistochemistry and molecular cytogenetics are providing substantial new information, allowing the development of new diagnostic criteria and hence facilitating an accurate diagnosis. It is the aim of this short review to highlight the most prevalent soft tissue tumours with predominantly myxoid morphology, to describe the features by which the majority of these myxoid lesions may be identified, and to discuss the differential diagnosis where appropriate.     

Intratumoural lymphatics in benign and malignant soft tissue tumours

Soft tissue sarcomas do not generally metastasise via lymphatics, and the presence or absence of lymphatic vessels within sarcomas and benign soft tissue tumours is not known. In this study, we determined whether lymphatic vessels were present in a wide range of benign and malignant soft tissue lesions by examining intratumoural expression of the lymphatic endothelial cell markers, Lyve-1 and podoplanin. Intratumoural Lyve-1+/podoplanin+ lymphatics were not identified in sarcomas apart from all cases of epithelioid sarcoma (a tumour which is known to metastasise to lymph nodes) and a few cases of leiomyosarcoma, rhabdomyosarcoma and synovial sarcoma. Intratumoural lymphatics were also absent in most benign soft tissue tumours. Reparative and inflammatory soft tissue lesions contained lymphatics, as did all (pseudosarcomatous) proliferative myofibroblastic lesions including nodular, proliferative and ischaemic fasciitis, elastofibroma, nuchal fibroma and deep fibromatosis. Our results show that most soft tissue sarcomas do not contain intratumoural lymphatics, a finding which is consistent with the infrequent finding of sarcoma metastasis to lymph nodes. In contrast to fibrosarcoma and a number of other malignant spindle cell tumours, proliferative fibroblastic/myofibroblastic lesions of soft tissue contain intralesional lymphatic vessels.     

The role of microarray technologies in the study of soft tissue tumours

Array technologies (gene array, tissue microarray and others) are being used in a growing number of research projects involving soft tissue tumours. Gene array techniques allow for measurements of RNA expression levels or gene copy number changes for a large number of genes in a single specimen. A complementary technique, tissue microarrays, allows for the measurement of expression of a single gene in a large number of specimens. These techniques and similar ones have created a fundamentally new approach to the investigation of soft tissue tumours. This review addresses some of the advantages, problems, and solutions to those problems that come with these technologies.     

Autocrine motility factor/glucose-6-phosphate isomerase is a possible predictor of metastasis in bone and soft tissue tumours

In order to assess the involvement of autocrine motility factor (AMF) in mesenchymal tumours, AMF protein and mRNA expression was analysed in tumours, tumour-like lesions, and other lesions of bone and soft tissue. Immunohistochemical analysis of 200 cases revealed positive staining in 72.5% of the cases, suggesting that AMF is a widely expressed protein. Chordoid, chondroid, and muscular tumours revealed higher immunoreactivity in both benign and malignant tumours. Immunoblotting analysis corroborated the results of immunohistochemistry. Generally, malignant tumours revealed higher expression of AMF than benign tumours of the same histopathological lineage, except for dermatofibroma/dermatofibrosarcoma protuberans. However, mRNA levels were not concordant with protein levels, and sarcomas that displayed higher mRNA and lower protein expression levels showed a trend for distant metastasis. In cultured cells, AMF was secreted and detected in conditioned culture medium. Furthermore, when proteasome inhibitors were added to cells in order to examine the changes in turnover rates, these compounds did not significantly alter the intracellular levels of AMF protein. On the basis of these overall findings, it is suggested that a particular subset of sarcomas secrete AMF, rather than degrading this protein at a higher turnover rate. This secreted AMF presumably enhances their cell motility through an autocrine effect and eventually causes increased metastatic potential. Collectively, AMF was observed in a wide spectrum of lesions of mesenchymal tissue, supporting the notion that it is involved in various cellular functions, including proliferation, differentiation, metabolism, and metastasis. In addition, higher expression of its mRNA may indicate higher levels of protein secretion and define a particularly aggressive group of tumours with high metastatic potential.     

Myxoid tumours of soft tissue: the so-called myxoid extracellular matrix is heterogeneous in composition

Aim:  Myxoid tumours of soft tissue are characterized by their so-called 'myxoid' extracellular matrix. The aim was to investigate the composition and possible function of this matrix which is poorly understood.
Methods and results:  Using Alcian Blue staining with and without pretreatment with hyaluronidase and application of the critical electrolyte concentration method followed by densitometry, the glycosaminoglycan composition of three different myxoid tumours was studied. The composition of glycosaminoglycans varied with tumour type and grade, despite their general characterization as myxoid tumours. Intramuscular myxoma contained similar amounts of the various glycosaminoglycans as grade I myxofibrosarcoma; grade III myxofibrosarcoma contained less hyaluronic acid and more heparan sulphate, whereas extraskeletal myxoid chondrosarcoma contained predominantly chondroitin-4 and -6 sulphates. Western blot identified albumin as a major protein in tumour lysates, and its presence in the extracellular matrix and cytoplasm of the majority of tumours was demonstrated by immunohistochemistry; production of albumin by the tumour cells was confirmed by quantitative polymerase chain reaction.
Conclusions:  The extracellular matrix of myxoid tumours of soft tissue has a heterogeneous composition consisting of, amongst others, glycosaminoglycans and albumin, which appear to play an active role in their morphogenesis.     

小腿骨外露及皮肤软组织缺损的修复

目的探讨修复小腿骨外露及皮肤软组织缺损的各种方法，以便于更好地用于临床。方法25例小腿不同部位的骨外露分别采用皮片移植、带蒂皮瓣及肌皮瓣转移、皮瓣及肌皮瓣游离移植等方法，覆盖外露的骨面。结果19例全部存活，3例皮瓣部分坏死，2例创口延迟愈合，1例游离皮瓣失败。结论对小腿骨外露及皮肤软组织缺损应尽量采用皮瓣及肌皮瓣的转移或移植来修复，修复创面、恢复功能的目的。     

p53 protein expression in non-neoplastic lesions and benign and malignant neoplasms of soft tissue

Alterations of the p53 tumour suppressor gene, with consequent nuclear p53 protein accumulation, are among the most common genetic lesions in human neoplasms. In the present paper we show p53 immunoreactivity in 65% of malignant and 21% of intermediate malignancy soft tissue tumours, and in 48% of benign/reactive soft tissue lesions. p53 immunoreactivity of sarcomas can be interpreted as an indirect indication of a mutation of the corresponding p53 gene, suggesting that its alteration may have a role in their pathogenesis. Our data on p53 immunoreactivity in benign lesions of the soft tissues are among the first demonstrations of p53 over-expression in benign/reactive conditions. We cannot exclude mutations of the p53 gene in these cases, but it is difficult to sustain this hypothesis in reactive/pseudoneoplastic lesions. Alternatively p53 immunoreactivity in benign processes could be due to an increase in wild-type p53 as a result of different physiological mechanisms (cell type-specific p53 regulation, cell maturation, DNA repair). Our results do not indicate that immunohistochemical demonstration of p53 expression is a marker of malignancy in soft tissue tumours and therefore is of limited use in differential diagnosis. However, they suggest the need for further molecular genetic studies in order to elucidate the biological significance of the abnormal expression of p53 in benign soft tissue lesions.     

Immunohistochemistry of soft tissue tumours: a review

The diagnosis and classification of soft tissue sarcomas can pose difficult problems for the histopathologist. Many sarcomas are too poorly differentiated to exhibit morphological features specific enough to define their histogenesis. Using the immunoperoxidase technique with commercially available antisera as a routine adjunct to other diagnostic aids, it is possible to arrive at more accurate diagnoses on which treatment protocols can be based. In addition a better understanding of mesenchymal neoplasms and their origins can be obtained by functional immunohistochemical studies.     

The unsuspected soft tissue chondrosarcoma

Five cases of undifferentiated soft tissue sarcomas have been studied with particular reference to the identification of their mucosubstances. The use of alcian blue in solutions of magnesium chloride is described. It is suggested that undifferentiated soft tissue chondrosarcomas may be missed owing to inadequate investigation.     

Immunohistochemical and clinical evaluation of cathepsin expression in soft tissue sarcomas

Lysosomal proteases are known to enhance the spread of epithelial tumour cells, but little is known of the possible role of proteases in the growth of soft tissue sarcomas (STS). We investigated the expression of cathepsins D, B, S, H, L and procathepsin L in frozen sections of 34 STS from 34 patients by immunohistochemistry (IHC). Cathepsins D, B and H were relatively highly expressed in STS (77–91%). The expression rate of cathepsins S and L and of procathepsin L was lower (40–66%). Cathepsin S and L expression showed a moderate (P = 0.078 andP = 0.019) and procathepsin L a strong (P = 0.00001) correlation with the survival rate of STS patients. Cathepsin S expression is also correlated with the local recurrence rate (P < 0.01). Lysosomal proteases may play a role in STS progression, and cathepsin expression may also have, significance as a prognostic factor in STS.     

Loss of KAI1/CD82 expression in bone and soft tissue tumors is not associated with lung metastasis

The KAI1 gene has been identified as a metastasis suppressor gene in human prostate cancer. Decrease or loss of KAI1/CD82 expression has been shown to be associated with poorer prognosis and metastasis in carcinomas of various organs. The purpose of this study was to examine whether KAI1/CD82 is expressed in bone and soft tissue tumors, and whether it is associated with metastasis to the lungs. Immunohistochemically, KAI1/CD82 expression in benign and malignant soft tissue tumors was noted in 83% and 37% of cases, respectively. KAI1/CD82 was- also expressed in benign bone tumors and osteosarcomas in 67% and 36% of the cases, respectively. Four (40%) of 10 osteosarcoma cases with no lung metastasis and one (25%) of four osteosarcoma cases with lung metastasis were positive for KAI1/CD82, respectively. Metastasis of osteosarcoma cells to the lungs was not correlated with the loss of KAI1/CD82 in osteosarcoma cells.     

Cartilage-forming tumours of bone and soft tissue and their differential diagnosis

The prevalence of primary malignant bone tumours is estimated to be 1:100,000 within the general population: 17–24% of these are malignant cartilaginous tumours (chondrosarcomas). The incidence of benign bone tumours is largely unknown, due to lack of registration as well as frequent failure to present clinically. Benign cartilaginous tumours of bone include chondroma, osteochondroma, chondroblastoma and chondromyxoid fibroma, whereas among the malignant cartilaginous bone tumours conventional, juxtacortical, mesenchymal, dedifferentiated, and clear cell chondrosarcomas are recognized. The histological distinction between the different entities is based on cell type/differentiation, matrix formation and architecture, combined with radiodiagnostic and clinical data. Extraskeletal cartilaginous lesions are extremely uncommon and include soft tissue chondroma, mesenchymal and extraskeletal myxoid chondrosarcoma. The formation of cartilaginous matrix can be found in many other non-cartilaginous tumours (such as periosteal osteosarcoma and chondroblastic osteosarcoma) and tumour-like lesions (such as fibrous dysplasia, Nora's lesion, primary synovial chondromatosis, dysplasia epiphysealis hemimelica and callus formation) These conditions may lead to an erroneous diagnosis of a primary osseous cartilaginous tumour.     

Recent developments in soft tissue tumours

This article reviews the clinicopathological features of several recently described soft tissue tumours, namely ossifying fibromyxoid tumour, angiomyofibroblastoma, epithelioid angiosarcoma, retiform haemangioendothelioma, intra-abdominal desmoplastic small cell tumour, spindle cell liposarcoma and low grade fibromyxoid sarcoma. Conceptual changes are also discussed. These include the relationship between Ewing's sarcoma and peripheral primitive neuroectodermal tumour, the proposed use of the term atypical lipoma for a subset of well differentiated liposarcomas, and the occurrence at a wide variety of sites of inflammatory myofibroblastic lesions of uncertain biological potential. In addition, advances in the study of soft tissue lesions at the molecular and cytogenetic levels are outlined, with particular emphasis on the recent identification of tumour-specific karyotypic abnormalities in a wide variety of sarcomas.     

Immunohistochemistry in diagnosis of soft tissue tumours

Immunohistochemistry in soft tissue tumours, and especially sarcomas, is used to identify differentiation in the neoplastic cells. In some cases, specific antigens are expressed; however, an initial panel of antibodies is often required in order to establish the broad lineage, with a subsequent, more focused, panel to allow classification. Immunohistochemical evaluation must be employed with the clinical picture, the morphology, and, when necessary, other ancillary techniques such as molecular genetics and cytogenetics. Whereas some diagnoses are evident on morphology, many soft tissue neoplasms are seen microscopically as spindle cell, epithelioid cell, small round cell or pleomorphic tumours that need to be further characterized. This article reviews selected applications of immunohistochemistry in the diagnosis of each of the principal morphological groups, concentrating on areas of most use in daily practice.     

Soft tissue tumours in childhood

The spectrum of soft tissue tumours in youg adults is very similar to that in more mature individuals, while those in childhood form a distinct group rarely seen outside the first decade. The majority of these are benign vascular or fibroblastic proliferations; in young children they may be highly cellular and mitotically active, but malignancy should be diagnosed with caution. Congenital soft tissue tumours constitute a special group in which the clinical outcome may be particularly difficult to predict from the histological appearances. This review focuses on those malignant soft tumours which are either peculiar to childhood or which manifest special features in childhood. Some recently recognized benign soft tissue tumours which occur mainly in childhood are also described. The fibromatoses are not discussed. As a guide to the appropriate treatment regime, the main histological distinctions to be drawn are between: 1 tumours of neuroectodermal origin (Ewing's sarcoma and primitive neuroectodermal tumour); 2 other sarcomas; and 3 the fibromatoses and other benign and potentially locally aggressive lesions requiring local excision. Immunohistochemical staining may be of considerable help in achieving the correct diagnosis, but it is vital that a panel of antibodies be applied and the results critically assessed. Cytogenetic analysis is also of growing importance, characteristic karyotypic abnormalities having been demonstrated in Ewing's sarcoma/primitive neuroectodermal tumour, alveolar rhabdomyosarcoma and synovial sarcoma.     

Immunohistochemical and ultrastructural localization of tissue polypeptide antigen in human ovarian tumours

Summary Forty specimens of benign and malignant ovarian tumours were studied for localization of tissue polypeptide antigen (TPA) at light and electron microscopic levels by an indirect immunoperoxidase technique. Of the 30 ovarian carcinomas, 23 (77%) were positive and 7 (23%) were negative for TPA, while of the 10 benign ovarian tumours 3 (30%) were positive and 7 (70%) were negative. Positive reaction did not correlate with the tumour grade. Of the 10 patients with metastasis, 8 (80%) had positive tumours. Staining for TPA was observed at the intraluminal cell surfaces and peripheral cell membranes. The ultrastructural localization of TPA revealed electron-dense reaction products at the cell surface and microvillous surfaces. These results provide confirmatory and supplementary evidence to support the previous findings of TPA in the serum and suggest that testing for TPA in ovarian tumors has a limited prognostic importance and a poor diagnostic value. The surface property of TPA suggests that the cell membrane is involved in secretion and probably synthesis of TPA.