Epithelial-type and neural-type cadherin expression in malignant noncarcinomatous neoplasms with epithelioid features that involve the soft tissues

Chondrosarcoma of the spine: a narrative review

Chondrosarcoma is an uncommon primary bone tumor with an estimated incidence of 0.5 per 100,000 patient-years. Primary chondrosarcoma of the mobile spine and sacrum cumulatively account for less than 20% of all cases, most .commonly causing patients to present with focal pain with or without radiculopathy, or myelopathy secondary to neural element compression. Because of the rarity, patients benefit from multidisciplinary care at academic tertiary-care centers. Current standard-of-care consists of en bloc surgical resection with negative margins; for high grade lesions adjuvant focused radiation with ≥60 gray equivalents is taking an increased role in improving local control. Prognosis is dictated by lesion grade at the time of resection. Several groups have put forth survival calculators and epidemiological evidence suggests prognosis is quite good for lesions receiving R0 resection. Future efforts will be focused on identifying potential chemotherapeutic adjuvants and refining radiation treatments as a means of improving local control.

Matrix metalloproteinase-14 induces epithelial-to-mesenchymal transition in synovial sarcoma

Synovial sarcoma (SS) is a highly aggressive malignant soft tissue sarcoma with typical characteristics of both epithelial and mesenchymal differentiation. Matrix metalloproteinase-14 (MMP-14) is reported to play an important role in some of these tumors. It induces epithelial-to-mesenchymal transition (EMT) in some carcinomas, such as breast and prostate cancers. However, the role of MMP-14 in the pathogenesis of SS remains unclear. Therefore, we investigated the role of MMP-14 and EMT/mesenchymal-to-epithelial transition in SS. The expression of MMP-14 and EMT-related proteins was determined in 37 SS cases and transfected cells by immunohistochemistry staining and Western blotting. The invasion ability of transfected cells was determined by transwell invasion assay. The expression rates of MMP-14, E-cadherin, N-cadherin, and vimentin were 75.7%, 54.1%, 75.7%, and 100%, respectively, in the cases of SS. The expression of MMP-14 correlated negatively with E-cadherin and positively with N-cadherin in monophasic fibrous SS. The MMP-14 protein expression was higher in stage III/IV than in stage I/II. After MMP-14 was transfected into SW982 cells, MMP-14, N-cadherin, and vimentin expression was up-regulated, and E-cadherin expression was down-regulated. High expression of MMP-14 enhanced the invasive ability of SW982 cells. Our findings suggest that MMP-14 enhances the invasive ability of SW982 cells by inducing EMT. By this action, it may play an important role in the occurrence and development of SS.

Role of N-cadherin in proliferation, migration, and invasion of germ cell tumours

Germ cell tumors (GCTs) are the most common malignancies in young men. Most patients with GCT can be cured with cisplatin-based combination chemotherapy, even in metastatic disease. In case of therapy resistance, prognosis is usually poor. We investigated the potential of N-cadherin inhibition as a therapeutic strategy. We analyzed the GCT cell lines NCCIT, NTERA-2, TCam-2, and the cisplatin-resistant sublines NCCIT-R and NTERA-2R. Effects of a blocking antibody or siRNA against N-cadherin on proliferation, migration, and invasion were investigated. Mouse xenografts of GCT cell lines were analyzed by immunohistochemistry for N-cadherin expression. All investigated GCT cell lines were found to express N-cadherin protein in vitro and in vivo. Downregulation of N-cadherin in vitro leads to a significant inhibition of proliferation, migration, and invasion. N-cadherin-downregulation leads to a significantly higher level of pERK. N-cadherin-inhibition resulted in significantly higher rates of apoptotic cells in caspase-3 staining. Expression of N-cadherin is preserved in cisplatin-resistant GCT cells, pointing to an important physiological role in cell survival. N-cadherin-downregulation results in a significant decrease of proliferation, migration, and invasion and stimulates apoptosis in cisplatin-naive and resistant GCT cell lines. Therefore, targeting N-cadherin may be a promising therapeutic approach, particularly in cisplatin-resistant, therapy refractory and metastatic GCT.

Epithelioid Sarcoma: Diagnostic Features and Genetics

Epithelioid sarcoma (ES) is a rare, aggressive soft-tissue neoplasm of uncertain differentiation, characterized by nodular aggregates of epithelioid cells, which are immunoreactive to cytokeratins (CKs) and epithelial membrane antigen, and often for CD34. It has a propensity for multifocal disease at presentation, local recurrence, and regional metastasis. These are aggressive neoplasms with particularly poor prognosis after regional or distant metastatic disease, for which surgical resection is still the mainstay of treatment, and options for patients with metastatic disease remain undefined. There are 2 distinct variants: classic ES, which typically presents as a subcutaneous or deep dermal mass in the distal extremities of young adults and comprises nodular distributions of relatively uniform epithelioid cells with central necrosis, and the proximal variant, which has a predilection for proximal limbs and limb girdles and the midline of the trunk, which is composed of sheets of larger, more atypical cells with variable rhabdoid morphology. Both classic and proximal-type ESs are associated with the loss of SMARCB1/INI1 protein expression, but appear otherwise molecularly relatively heterogeneous. We review classic and proximal-type ES, discussing morphology, immunohistochemical and genetic findings, the differential diagnosis, and the future potential for targeted therapies.

Chordoma: the entity

Chordomas are malignant tumors of the axial skeleton, characterized by their locally invasive and slow but aggressive growth. These neoplasms are presumed to be derived from notochordal remnants with a molecular alteration preceding their malignant transformation. As these tumors are most frequently observed on the skull base and sacrum, patients suffering from a chordoma present with debilitating neurological disease, and have an overall 5-year survival rate of 65%. Surgical resection with adjuvant radiotherapy is the first-choice treatment modality in these patients, since chordomas are resistant to conventional chemotherapy. Even so, management of chordomas can be challenging, as chordoma patients often present with recurrent disease. Recent advances in the understanding of the molecular events that contribute to the development of chordomas are promising; the most novel finding being the identification of brachyury in the disease process. Here we present an overview of the current paradigms and summarize relevant research findings.

Mesenchymal to epithelial transition in sarcomas

Mesenchymal to epithelial transition (MET) in carcinomas has been proposed to promote the growth of epithelial tumour cells at distant sites during metastasis. MET has also been suggested as an important biological and clinical process in mesenchymal tumors, sarcomas. Here we review studies on MET in sarcomas, including molecular markers, signalling mechanisms, regulation by micro RNAs and therapeutic implications. Accumulating evidences suggest that deeper investigation and understanding of MET in sarcomas would shed light on the pathogenesis of sarcomas and might lead to identification of potential clinical biomarkers for prognosis and targets for sarcoma therapeutics.

Differential remodeling of cadherins and intermediate cytoskeletal filaments influence microenvironment of solid and ascitic sarcoma

Different forms of sarcoma (solid or ascitic) often pose a critical medical situation for pediatric or adolescent group of patients. To date, predisposed genetic anomalies and related changes in protein expression are thought to be responsible for sarcoma development. However, in spite of genetic abnormality, role of tumor microenvironment is also indispensable for the evolving neoplasm. In our present study, we characterized the deferentially remodeled microenvironment in solid and ascitic tumors by sequential immunohistochemistry and flowcytometric analysis of E-cdaherin, N-cadherin, vimentin, and cytokeratin along with angiogenesis and metastasis. In addition, we considered flowcytometric apoptosis and CD133 positive cancer stem cell analysis. Comparative hemogram was also considered as a part. Our investigation revealed that both types of tumor promoted neovascularization over time with sign of local inflammation. Invasion of neighboring skeletal muscle by solid sarcoma was more frequent than its ascitic counterpart. In contrary, rapid and earlier cadherin switching (E-cadherin to N-cadherin) in ascitic sarcoma made them more aggressive than that of solid sarcoma and helped to early metastasize distant tissue like liver through the hematogenous route. Differential cadherin switching and infidelity of cytokeratin expression in Vimentin positive sarcoma also influenced the behavior of ascitic CD133+ cancer initiating cell pool with respect to CD133+ cells housed in solid sarcoma. Therefore our study concludes that differential cadherin switching program and infidelity of intermediate filaments in part, sharply discriminate the severity and metastatic potentiality of either type of sarcoma accompanying with CD133+ cellular repertoire. Besides, tumor phenotype-based dichotomous cadherin switching program could be exploited as a future drug target to manage decompensated malignant ascitic and solid sarcoma.

Soluble Neural-cadherin as a novel biomarker for malignant bone and soft tissue tumors

BACKGROUND

Neural-cadherin (N-cadherin) is one of the most important molecules involved in tissue morphogenesis, wound healing, and the maintenance of tissue integrity. Recently, the cleavage of N-cadherin has become a focus of attention in the field of cancer biology. Cadherin and their ectodomain proteolytic shedding play important roles during cancer progression. The aims of this study are to investigate the serum soluble N-cadherin (sN-CAD) levels in patients with malignant bone and soft tissue tumors, and to evaluate the prognostic significance of the sN-CAD levels.

METHODS

We examined the level of serum sN-CAD using an ELISA in 80 malignant bone and soft tissue tumors (bone sarcoma, n = 23; soft tissue sarcoma, n = 50; metastatic cancer, n = 7) and 87 normal controls. The mean age of the patients was 51 years (range, 10-85 years) and the mean follow-up period was 43 months (range, 1-115 months).

RESULTS

The median serum sN-CAD level was 1,267 ng/ml (range, 135-2,860 ng/ml) in all patients. The mean serum sN-CAD level was 1,269 ng/ml (range, 360-2,860 ng/ml) in sarcoma patients, otherwise 1,246 ng/ml (range, 135-2,140 ng/ml) in cancer patients. The sN-CAD levels in patient were higher than those found in the controls, who had a median serum level of 108 ng/ml (range, 0-540 ng/ml). The patients with tumors larger than 5 cm had higher serum sN-CAD levels than the patients with tumors smaller than 5 cm. The histological grade in the patients with higher serum sN-CAD levels was higher than that in the patients with lower serum sN-CAD levels. A univariate analysis demonstrated that the patients with higher serum sN-CAD levels showed a worse disease-free survival rate, local recurrence-free survival rate, metastasis-free survival rate, and overall survival rate compared to those with lower serum sN-CAD levels. In the multivariate analysis, sN-CAD was an independent factor predicting disease-free survival.

CONCLUSIONS

sN-CAD is a biomarker for malignant bone and soft tissue tumors, and a potentially valuable pre-therapeutic prognostic factor in patients with bone and soft tissue sarcoma.

FOXM1 (Forkhead box M1) in tumorigenesis: overexpression in human cancer, implication in tumorigenesis, oncogenic functions, tumor-suppressive properties, and target of anticancer therapy

FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor and is also intimately involved in tumorigenesis. FOXM1 stimulates cell proliferation and cell cycle progression by promoting the entry into S-phase and M-phase. Additionally, FOXM1 is required for proper execution of mitosis. In accordance with its role in stimulation of cell proliferation, FOXM1 exhibits a proliferation-specific expression pattern and its expression is regulated by proliferation and anti-proliferation signals as well as by proto-oncoproteins and tumor suppressors. Since these factors are often mutated, overexpressed, or lost in human cancer, the normal control of the foxm1 expression by them provides the basis for deregulated FOXM1 expression in tumors. Accordingly, FOXM1 is overexpressed in many types of human cancer. FOXM1 is intimately involved in tumorigenesis, because it contributes to oncogenic transformation and participates in tumor initiation, growth, and progression, including positive effects on angiogenesis, migration, invasion, epithelial-mesenchymal transition, metastasis, recruitment of tumor-associated macrophages, tumor-associated lung inflammation, self-renewal capacity of cancer cells, prevention of premature cellular senescence, and chemotherapeutic drug resistance. However, in the context of urethane-induced lung tumorigenesis, FOXM1 has an unexpected tumor suppressor role in endothelial cells because it limits pulmonary inflammation and canonical Wnt signaling in epithelial lung cells, thereby restricting carcinogenesis. Accordingly, FOXM1 plays a role in homologous recombination repair of DNA double-strand breaks and maintenance of genomic stability, that is, prevention of polyploidy and aneuploidy. The implication of FOXM1 in tumorigenesis makes it an attractive target for anticancer therapy, and several antitumor drugs have been reported to decrease FOXM1 expression.

N-cadherin expression in malignant germ cell tumours of the testis

BACKGROUND

Testicular germ cell tumours (TGCTs) are the most common malignancy in young men aged 18-35 years. They are clinically and histologically subdivided into seminomas and non-seminomas. Cadherins are calcium-dependent transmembrane proteins of the group of adhesion proteins. They play a role in the stabilization of cell-cell contacts, the embryonic morphogenesis, in the maintenance of cell polarity and signal transduction. N-cadherin (CDH2), the neuronal cadherin, stimulates cell-cell contacts during migration and invasion of cells and is able to suppress tumour cell growth.

METHODS

Tumour tissues were acquired from 113 male patients and investigated by immunohistochemistry, as were the three TGCT cell lines NCCIT, NTERA-2 and Tcam2. A monoclonal antibody against N-cadherin was used.

RESULTS

Tumour-free testis and intratubular germ cell neoplasias (unclassified) (IGCNU) strongly expressed N-cadherin within the cytoplasm. In all seminomas investigated, N-cadherin expression displayed a membrane-bound location. In addition, the teratomas and yolk sac tumours investigated also differentially expressed N-cadherin. In contrast, no N-cadherin could be detected in any of the embryonal carcinomas and chorionic carcinomas examined. This expression pattern was also seen in the investigated mixed tumours consisting of seminomas, teratomas, and embryonal carcinoma.

CONCLUSIONS

N-cadherin expression can be used to differentiate embryonal carcinomas and chorionic carcinomas from other histological subtypes of TGCT.

Expression of E-cadherin in angiomyolipoma

Angiomyolipoma is the most common member of perivascular epithelioid cell tumors that characteristically express myogenic and melanocytic markers. E-cadherin is a calcium-dependent cell-cell adhesion molecule that is repressed in epithelial to mesenchymal transition occurring in carcinomas. E-cadherin has not, thus far, been systematically studied in angiomyolipoma. We analyzed a series of 42 angiomyolipomas with E-cadherin and discussed its clinicopathologic significance. Forty-two cases of angiomyolipomas (35 renal, 5 hepatic, and 2 retroperitoneal) were examined histologically. E-cadherin was investigated immunohistochemically and compared with other significant markers found in angiomyolipoma in all cases. The percentages of tumors staining positively were E-cadherin (98%), smooth muscle actin (98%), actin (93%), HMB-45 (93%), Melan-A (90%), S-100 (38%), and CD117 (60%). The intensity of E-cadherin staining was moderate to strong in 30 cases (71%). E-cadherin stained both the cytoplasm and cell membrane of tumor cells, but membrane staining was stronger in the epithelioid tumor cells than in the spindle-shaped tumor cells. E-cadherin may serve as an additional diagnostic marker for angiomyolipoma. Angiomyolipoma should be included in the differential diagnosis of E-cadherin-positive tumors. Stronger membrane immunoreactivity for E-cadherin in epithelioid tumor cells is possibly related to constitution of their epithelioid architecture, but the pathogenetic significance of E-cadherin in angiomyolipoma remains to be further studied.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

The molecular biology of soft-tissue sarcomas and current trends in therapy

Basic research in sarcoma models has been fundamental in the discovery of scientific milestones leading to a better understanding of the molecular biology of cancer. Yet, clinical research in sarcoma has lagged behind other cancers because of the multiple clinical and pathological entities that characterize sarcomas and their rarity. Sarcomas encompass a very heterogeneous group of tumors with diverse pathological and clinical overlapping characteristics. Molecular testing has been fundamental in the identification and better definition of more specific entities among this vast array of malignancies. A group of sarcomas are distinguished by specific molecular aberrations such as somatic mutations, intergene deletions, gene amplifications, reciprocal translocations, and complex karyotypes. These and other discoveries have led to a better understanding of the growth signals and the molecular pathways involved in the development of these tumors. These findings are leading to treatment strategies currently under intense investigation. Disruption of the growth signals is being targeted with antagonistic antibodies, tyrosine kinase inhibitors, and inhibitors of several downstream molecules in diverse molecular pathways. Preliminary clinical trials, supported by solid basic research and strong preclinical evidence, promises a new era in the clinical management of these broad spectrum of malignant tumors.

N-cadherin mediates angiogenesis by regulating monocyte chemoattractant protein-1 expression via PI3K/Akt signaling in prostate cancer cells

Over the past decade, evidence continues to mount showing that N-cadherin is a critical protein in cancer progression and metastasis. In the present study, we evaluated the expression of N-cadherin in human prostate cancer tissue specimens and cell lines. Enhanced expression of N-cadherin was observed in both the malignant and bone-metastasized prostate tissue specimens compared to the healthy prostate tissues. Consistent with the tissue array data, N-cadherin was highly expressed in PC3, but not in Du145 and LNCaP human prostate cell lines. Based on cell to cell binding assay, we found that N-cadherin expression facilitates homotypic interaction between human prostate cancer cells and human microvascular endothelial cells (HMEC). Human angiogenesis antibody array and in vitro angiogenesis assay showed that siRNA-mediated knockdown of N-cadherin reduced the secretion of monocyte chemoattractant protein-1 (MCP-1), which played a potential role in stimulating capillary network formation of HMEC. Additionally, culture supernatant of Du145 cells transfected with full-length N-cadherin expressing plasmid showed increased MCP-1 expression and chemoattractant ability compared to normal Du145 cells. Further, we noticed that blocking PI3K activity inhibited N-cadherin mediated MCP-1 expression. Our data demonstrated that N-cadherin in prostate cancer cell mediates cell-cell adhesion and regulates MCP-1 expression via the PI3K/Akt signaling pathway.

Immunohistochemical Study of Correlation Between Histologic Subtype and Expression of Epithelial-Mesenchymal Transition-Related Proteins in Synovial Sarcomas

Context.—Synovial sarcomas are mesenchymal tumors with epithelial nature and comprise biphasic and monophasic fibrous subtypes. However, factors determining epithelial or spindle cell differentiation are still unexplored. Aberrant epithelial-mesenchymal transition has been implicated in the pathogenesis of diverse human malignancies.

Objective.—To analyze the correlation between cellular phenotype and expression of proteins associated with different epithelial-mesenchymal transition-related pathways.

Design.—Immunohistochemical analysis of E-cadherin, Snail, Slug, and dysadherin, components of the Wnt/wingless and PI3K/Akt pathways, was performed on 14 biphasic and 27 monophasic fibrous tumors.

Results.—In monophasic fibrous tumors, increased expression of Snail (17 of 27; 63%), Slug (18 of 27; 67%), and dysadherin (14 of 27; 52%) and activation of Wnt (nucleocytoplasmic β-catenin accumulation in 63%; n  =  27; and positive expression of GSK3 and pGSK3 in 24 of 27 [89%] and 21 of 27 [78%], respectively) and PI3K/Akt (Akt: 22 of 27 [81%]; pAkt: 25 of 27 [93%]; and PI3K: 20 of 27 [74%]) signaling correlated significantly with inactivated E-cadherin expression (1 of 27; 4%) (all P < .05). In contrast, preserved E-cadherin expression (12 of 14; 86%) in the glandular component of the biphasic subtype was associated with significantly decreased Snail (3 of 14; 21%) (P  =  .02) and dysadherin (2 of 14; 14%) expression (P < .001).

Conclusions.—Overexpression of Snail, Slug, and dysadherin and activation of Wnt and PI3K/Akt signaling was associated with inactivated E-cadherin in the spindle cells of monophasic fibrous synovial sarcomas, further supporting the hypothesis that this subtype may have developed through neoplastic epithelial-mesenchymal transition.

Markers of epithelial-mesenchymal transition and epithelial differentiation in sarcomatoid carcinoma: utility in the differential diagnosis with sarcoma

The distinction between sarcomatoid carcinoma (SC) and bona fide sarcoma can be difficult using conventional immunohistochemical markers. Epithelial-mesenchymal transition (EMT) has been proposed as a histogenetic mechanism for the development of SC. Expression of selected markers of EMT (Twist and Slug) was compared with other markers of epithelial differentiation in SC and spindle cell sarcoma to determine the utility of these antigens in this differential diagnosis. Twenty-seven cases of SC (excluding those of gynecologic origin) were stained by immunohistochemistry for cytokeratins (AE1/AE3, 5D3, CK5/6, and 34betaE12), p63, claudin-1, claudin-7, epithelial cadherin, placental cadherin, epithelial cell adhesion molecule/epithelial-specific antigen, 14-3-3sigma, Twist, and Slug. A comparison group of 21 spindle or pleomorphic spindle cell sarcomas was also studied. Immunohistochemical stains were scored in a semiquantitative manner and subsequent exploratory analyses were performed using logistic regression and chi2 tests. Only cytokeratin AE1/AE3 specifically labeled SC in a statistically significant manner. Other epithelial-specific markers tested did not distinguish SC from sarcoma primarily owing to low sensitivity. However, when positive, immunostains such as CK5/6, membranous epithelial cadherin, and nuclear p63 may aid in the distinction of SC from sarcoma. EMT markers were expressed in most cases of both SC and sarcoma, and were not useful in making a differential diagnosis between these neoplasms.

Epithelioid and Epithelial Neoplasms of Bone

Context.—Epithelioid and epithelial neoplasms seen in bone are rare and include epithelioid variants of vascular lesions, osteoblastoma, osteosarcoma, chordoma, and chondroblastoma as well as adamantinoma and metastatic carcinoma.

Objective.—To provide an overview of tumors with epithelioid histology and address the clinical context and diagnostic issues.

Data Sources.—Pertinent literature is reviewed with emphasis on recent and controversial issues.

Conclusions.—The differential diagnosis in epithelioid/ epithelial lesions of bone is limited. The primary consideration in many cases is distinguishing primary from metastatic lesions.

Dysadherin Expression as a Significant Prognostic Factor and as a Determinant of Histologic Features in Synovial Sarcoma: Special REFERENCE to its Inverse Relationship With E-cadherin Expression

Dysadherin is a cancer-associated cell membrane glycoprotein, which down-regulates E-cadherin and promotes metastasis. Synovial sarcoma is a very rare mesenchymal tumor that exhibits an epithelial profile. To confirm the diagnosis of synovial sarcoma, we evaluated several immunohistochemical markers, or detected SYT-SSX fusion gene transcript. We studied the clinicopathologic features in 92 synovial sarcoma patients and also assessed the immunohistochemical expression of dysadherin and E-cadherin to examine their possible association with histologic subtype and biologic behavior. Moreover, among 30 patients, for whom frozen materials were available, dysadherin mRNA expression was examined by reverse transcription-polymerase chain reaction and real-time quantitative reverse transcription-polymerase chain reaction analysis. Dysadherin-positive expression was significantly correlated with E-cadherin-reduced expression (P=0.0004). Dysadherin-positive immunostaining was diffusely observed in the membranes of tumor cells in 30/68 (44%) patients with monophasic fibrous type and in 1/2 (50%) patients with poorly differentiated type. However, in biphasic tumors, dysadherin expression in the fibrous component was not diffusely observed, but often sporadically or focally observed [20/22 (91%) patients]. In addition, dysadherin mRNA expression in monophasic fibrous type was significantly higher than in biphasic type (P=0.0079). Synovial sarcoma patients with dysadherin expression survived for a significantly shorter time than those without dysadherin expression (P=0.0006). Patients with combined dysadherin-positive expression and E-cadherin-reduced expression had a significantly worse prognosis than those with other combinations of dysadherin and E-cadherin expression (P=0.0007). SYT-SSX fusion gene transcript was detected in 39 patients. In our series, SYT-SSX fusion type was found to have no correlation with histologic subtype, prognosis, or dysadherin expression. In multivariate analysis, dysadherin immunopositivity (P=0.0411) was an independent adverse prognostic factor, in addition to a high MIB-1 labeling index (> or =10%). We conclude that E-cadherin dysfunction by dysadherin is associated with reduced E-cadherin expression and morphologic change from epithelioid to spindle phenotype. Dysadherin expression is considered to be one of the determinants of histologic subtype in synovial sarcoma. Moreover, dysadherin expression is an excellent and independent prognostic indicator.

From the archives of the AFIP: Imaging of synovial sarcoma with radiologic-pathologic correlation

Synovial sarcoma is the fourth most common type of soft-tissue sarcoma, accounting for 2.5%-10.5% of all primary soft-tissue malignancies worldwide. Synovial sarcoma most often affects the extremities (80%-95% of cases), particularly the knee in the popliteal fossa, of adolescents and young adults (15-40 years of age). Despite its name, the lesion does not commonly arise in an intraarticular location but usually occurs near joints. Histologic subtypes include monophasic, biphasic, and poorly differentiated; the cytogenetic aberration of the t(X;18) translocation is highly specific for synovial sarcoma. Although radiographic features of these tumors are not pathognomonic, findings of a soft-tissue mass, particularly if calcified (30%), near but not in a joint of a young patient, are very suggestive of the diagnosis. Cross-sectional imaging features are vital for staging tumor extent and planning surgical resection; they also frequently reveal suggestive appearances of multilobulation and marked heterogeneity (creating the "triple sign") with hemorrhage, fluid levels, and septa (creating the "bowl of grapes" sign). Two features associated with synovial sarcoma that may lead to an initial mistaken diagnosis of a benign indolent process are slow growth (average time to diagnosis, 2-4 years) and small size (< 5 cm at initial presentation); in addition, these lesions may demonstrate well-defined margins and homogeneous appearance on cross-sectional images. Synovial sarcoma is an intermediate- to high-grade lesion, and, despite initial aggressive wide surgical resection, local recurrence and metastatic disease are common and prognosis is guarded. Understanding and recognizing the spectrum of appearances of synovial sarcoma, which reflect the underlying pathologic characteristics, improve radiologic assessment and are important for optimal patient management.

SYT-SSX1 and SYT-SSX2 Interfere with Repression of E-Cadherin by Snail and Slug: A Potential Mechanism for Aberrant Mesenchymal to Epithelial Transition in Human Synovial Sarcoma

Synovial sarcoma is a primitive mesenchymal neoplasm characterized in almost all cases by a t(X;18) fusing the SYT transcriptional coactivator gene with either SSX1 or SSX2, with the resulting fusion gene encoding an aberrant transcriptional regulator. A subset of synovial sarcoma, predominantly cases with the SYT-SSX1 fusion, shows foci of morphologic epithelial differentiation in the form of nests of glandular epithelium. The striking spontaneous mesenchymal to epithelial differentiation in this cancer is reminiscent of a developmental switch, but the only clue to its mechanistic basis has been the observation that most cases of synovial sarcoma with glandular epithelial differentiation (GED) contain SYT-SSX1 instead of SYT-SSX2. We report here that SYT-SSX1 and SYT-SSX2 interact preferentially with Snail or Slug, respectively, and prevent these transcriptional repressors from binding to the proximal E-cadherin promoter as shown by coimmunoprecipitation and chromatin immunoprecipitation. Luciferase reporter assays reveal that SYT-SSX1 and SYT-SSX2 can respectively overcome the Snail- or Slug-mediated repression of E-cadherin transcription. This provides a mechanism by which E-cadherin expression, a prerequisite of epithelial differentiation, is aberrantly derepressed in synovial sarcoma and may also explain the association of GED with the SYT-SSX1 fusion because it interferes with Snail, the stronger repressor of the E-cadherin promoter. Thus, our data provide a mechanistic basis for the observed heterogeneity in the acquisition of epithelial characteristics in synovial sarcoma and highlight the potential role of differential interactions with Snail or Slug in modulating this phenotypic transition.

E-Cadherin expression in transitional cell carcinomas

The authors analyzed the expression of E-cadherin, one of the most important cell adhesion molecules, on histological slides of tumors of bladder cancer patients. The aim of the study was to see whether there is any association between E-cadherin expression and tumor grade, stage, age and gender of the patients, number of recurrences, or overall survival. The samples were examined in 51 primary bladder transitional cell carcinomas (TCC) of 50 patients, resected by transurethral resection (TUR) between January 1, 1996 and January 1, 1997. Immunoreactions were performed with monoclonal anti-human E-cadherin antibody. Forty of the fifty patients could be clinically followed. The analysis of the results on these forty patients was performed by contingency analysis and significance was assessed by chi2 test. No significant association between E-cadherin expression and tumor grade, stage, age or gender of the patients, the number of recurrences, or overall survival could be seen.

Epithelioid sarcoma of Enzinger

Epithelioid sarcoma was named in 1970 in a classic paper by Enzinger, who expanded the observations in a larger series in 1985. He defined a sarcoma with a peak incidence in young adult males and a predilection for extremities, involving subcutis or deeper tissue and extending along tendon sheaths or aponeuroses. The tumor forms nodules with central necrosis surrounded by bland polygonal cells with eosinophilic cytoplasm and peripheral spindling. Fibromalike, angiomatoid, and proximal aggressive variants (with larger cells, prominent nuceloi, and rhabdoid change) have since been described. Epithelioid sarcomas regularly express vimentin, cytokeratins, and epithelial membrane antigen, and about half are positive for CD34, but a wide range of other antigens can be expressed. S100 protein, desmin, and FLI-1 are usually negative. The ultrastructure displays epithelial and mesenchymal features including myofibroblastic differentiation. There are no specific genetic findings but several cases display chromosomal abnormalities in the 22q region. The tumor has no normal cellular counterpart and differs from both synovial sarcoma and carcinoma. There is a wide differential diagnosis from numerous benign and malignant conditions, including granuloma annulare, melanoma, and epithelioid vascular neoplasms. Epithelioid sarcoma has a high recurrence rate, which can be reduced by adequate surgery, and up to 40% metastasize, to regional lymph nodes, to lung, and other locations including scalp. Adverse prognostic factors include large size, male sex, older age, necrosis, vascular invasion, rhabdoid cytomorphology, and inadequate excision. Thirty-six years after Enzinger's original account, epithelioid sarcoma remains a clinically and pathologically distinct, indolent but aggressive sarcoma of indeterminate lineage.

Cadherins and catenins in clival chordomas: correlation of expression with tumor aggressiveness

The local invasiveness and occasional rapid growth of chordomas, despite optimal treatment, highlight the need to develop ways to predict their biologic behavior. Alterations in adhesion proteins have been shown to participate in proliferation, invasiveness, and metastasis in epithelial tumors. We therefore analyzed the expression of E-cadherin, N-cadherin, as well as their cytosolic binding proteins alpha-catenin, beta-catenin, and gamma-catenin, in 51 paraffin archived and 17 cryopreserved chordoma specimens. In the majority of chordomas, E-cadherin and N-cadherin expression was inversely correlated, whereas beta-catenin and gamma-catenin expression was directly correlated. By multivariate analysis, N-cadherin up-regulation correlated with a diminished recurrence-free survival, and E-cadherin down-regulation strongly correlated with increased probabilities of death as determined by the Kaplan-Meier log-rank test. There was a 3.28-fold increased probability of having a tumor recurrence and a 10.98-fold increased probability of dying when, respectively, N-cadherin was up-regulated and E-cadherin down-regulated. These results suggest that changes in the relative expression of the cadherin-catenin complex reflect chordoma aggressiveness; and that decreased expression of E-cadherin and increased expression of N-cadherin may underlie the transition from a less to a more aggressive tumor phenotype.

Evaluation of perineurial differentiation in epithelioid sarcoma

AIMS

To investigate the differentiation pattern of epithelioid sarcoma in terms of perineurial and endothelial differentiation, and its relationship to that of meningioma.

METHODS AND RESULTS

Nine cases of epithelioid sarcoma and five cases of meningioma were studied in an immunohistochemical analysis of 'perineurial' antigens [GLUT-1, claudin-1, epithelial membrane antigen (EMA) and VE-cadherin] and of 'endothelial' antigens not present on normal perineurium (CD34, CD31, Fli-1). Both epithelioid sarcoma and meningioma showed frequent expression of the perineurial markers GLUT-1, claudin-1 and EMA. VE-cadherin was identified in one of five meningiomas, and in the only case of epithelioid sarcoma in which suitably fixed material was available. CD34 was expressed by all epithelioid sarcomas studied but by none of the meningiomas. Fli-1 was present in a substantial majority of epithelioid sarcomas and by all the meningiomas. CD31 was not detected in any epithelioid sarcoma or meningioma.

CONCLUSIONS

The results were evaluated in the context of previous immunohistochemical, ultrastructural and genetic studies and suggest that epithelioid sarcoma may be a form of malignant perineurioma with a range of differentiation (epithelial features) akin to that seen in meningioma, reflecting the close relationship between perineurium and meningothelium.

Biphasic solitary fibrous tumour: a report of two cases with epithelioid features

We present two cases of solitary fibrous tumour (SFT) showing biphasic morphology with a spectrum of malignant epithelioid components. Slides prepared from formalin-fixed and paraffin-embedded tissue from both cases were stained with haematoxylin and eosin and by immunohistochemistry. Interphase fluorescent in situ hybridisation studies were performed in both cases using paraffin-embedded tissue to look for the t(X;18) translocation, thereby to exclude synovial sarcoma. Both cases showed biphasic morphology with some areas having typical benign spindled SFT morphology (including CD34 expression) and other areas having a malignant epithelioid appearance. In one of the cases, the epithelioid area, which was well circumscribed and showed packeting of cell groups, demonstrated expression of cytokeratin and epithelial cadherin but not of CD34. In the second case, the immunophenotype of the epithelioid component was similar to that of the benign SFT component. These findings suggest that epithelioid change in SFT shows a range of differentiation at one end, similar to that of a standard SFT, and at the other end, possibly acquiring epithelial characteristics.

Soft tissue sacrococcygeal chordoma with intracytoplasmic filamentous inclusions

Extraskeletal chordoma arising within soft tissue is a rare occurrence. We report a case of chordoma that is unusual both for its location within the subcutaneous soft tissue of the sacrococcygeal region without involvement of adjacent bones and for the presence of eosinophilic roundish inclusion bodies within the cytoplasm of tumor cells. These bodies revealed immunoreactivity for cytokeratin and a fibrillar, partly whorled structure on the electron microscopic examination, consistent with an intermediate filament-based composition. To our knowledge, this is the first report of chordoma featuring this cellular change although we do not know the significance of these bodies.

Methylation of tumor suppressor genes p16(INK4a), p27(Kip1) and E-cadherin in carcinogenesis

Not only genomic mutations but also abnormal epigenetic methylation can significantly contribute to gene silencing and carcinogenesis. Methylation is particularly often observed in the CpG islands of the promoter regions in the regulatory genes. However, there are considerable differences in the incidence of methylation e.g. in the tumor suppressor genes, so that aberrant methylation of p16(INK4a) is relatively frequently observed in tumors, p27(Kip1) methylation is rare, and the incidence of E-cadherin methylation occurs at an intermediate rate. Although true genomic defects are generally much less common than methylation, parallel tendencies for both are often observed, probably reflecting the different levels of evolutionary advantage for tumor cells from inactivation of different genes. This also suggests that loss of p27 expression could be more a consequence of carcinogenesis, while lost p16 expression is a true oncogenic event. Due to the role of p27 in maintaining cellular quiescence, however, loss of its expression can still be a useful partial indicator of the aggressiveness of cancer. Loss of E-cadherin or its catenin partners of cellular adhesion will result in increasing invasiveness and metastatic potential of neoplastic cells but, because of several alternative routes to the same effect, incidence of lost expression for one component gene like E-cadherin does not need to be very high. Similarly, there must be a relatively high number of genes with modest or low incidence of aberrant silencing by methylation, to reflect multiple alternatives for the multistep process of carcinogenesis. Nevertheless, methylation of different genes also shows characteristic differences between different cancer and tumor types, and the epigenetic methylation patterns therefore have considerable diagnostic and prognostic potential. Realising this potential requires efficient methods for profiling the status of methylation. Such profiling methods have only recently become available and are still under relatively rapid development.

Prognostic value of MIB-1, E-cadherin, and CD44 in pediatric chordomas

The prognosis of pediatric chordomas is difficult to predict based on histology. The objective of this study was to assess the expression of a proliferation marker and adhesion molecules in pediatric chordomas and relate the expressions to outcome. In 8 pediatric chordomas, we calculated the MIB-1 labeling index (LI) by counting the number of MIB-1-positive tumor cells in 100 tumor cells. The grade of expression of E-cadherin and CD44 was calculated by estimating the percentage of tumor cells expressing these markers. MIB-1 LI correlated with tumor recurrence (P = 0.007) and low survival rate (P = 0.007). The expression of E-cadherin correlated with disease-free survival (P = 0.009), tumor recurrence (P > 0.0007), and low survival rate (P > 0.0007). CD44 expression did not correlate with recurrence (P = 0.056) or survival rate (P = 0.056). Our results suggest that MIB-1 LI and expression of E-cadherin are helpful to predict outcome in pediatric chordomas.

E-cadherin mutation and Snail overexpression as alternative mechanisms of E-cadherin inactivation in synovial sarcoma

We have recently reported frequent E-cadherin gene mutations in synovial sarcoma (SS), suggesting mutational inactivation of E-cadherin as a potential mechanism of spindle cell morphology in SS, a spindle cell sarcoma that shows areas of glandular epithelial differentiaton in some cases (biphasic SS) and only pure spindle cell morphology in most cases (monophasic SS). However, the mechanism of downregulation of E-cadherin in SS remains unknown. To further address this issue, we analysed the mechanisms of E-cadherin silencing in 40 SS. Genetic and epigenetic changes in the E-cadherin gene, and the expression level of its transcriptional repressor Snail were examined by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP), methylation-specific PCR, and real-time quantitative PCR, respectively. Expression of E-cadherin was examined by RT-PCR and immunohistochemistry. We also examined ELF3, a transcription factor associated with epithelial differentiation in SS in a previous cDNA microarray, by RT-PCR. E-cadherin and ELF3 transcripts were detected, respectively, in 27/40 (67.5%) and in 25/40 (62.5%) of SS, and these epithelial-related genes were almost always coexpressed. Hypermethylation of the promoter of the E-cadherin gene was detected in five cases (12.5%) in SS; however, E-cadherin was silenced at mRNA level in only one of the five cases. E-cadherin missense mutations were observed in five cases (12.5%) of SS. In SS, all five cases with E-cadherin missense mutations had the SYT-SSX1 fusion and were monophasic tumors, suggesting a relationship between the SYT-SSX fusion type and E-cadherin missense mutation (P=0.07). E-cadherin mRNA expression in SS was associated with reduced Snail expression level (P=0.03). E-cadherin membranous expression was observed in 14/40 (35.0%) of SS, and was also correlated with SYT-SSX1 fusion type and biphasic histology. ELF3 was confirmed to be more highly expressed in biphasic than monophasic SS by real-time quantitative PCR. These results suggest that in SS the loss of E-cadherin expression occurs either by Snail trans-repression or by inactivating mutations. Thus, E-cadherin downregulation is associated with the loss or absence of glandular epithelial differentiation in certain SS.

Intra-abdominal synovial sarcoma: a clinicopathological study

AIMS

To evaluate a series of synovial sarcomas arising in the abdomen, pelvic cavity, or retroperitoneum. Synovial sarcoma is rare within the abdomen. In this location, it can be confused with other biphasic tumours and with other spindle and round cell sarcomas.

METHODS AND RESULTS

Cases were retrieved from archives. There were 11 intra-abdominal tumours among 300 synovial sarcomas in two referral practices (3.7%). Three were pelvic (two midline, one sidewall) and eight were retroperitoneal. They occurred in six males and five females aged from 25 to 75 years (mean 49 years, median 46 years), and ranged in diameter from 65 to 470 mm (mean 210 mm, median 150 mm). Six examples were biphasic, five were monophasic and seven had poorly differentiated areas. Monophasic tumours displayed at least one epithelial marker. One biphasic tumour had a SYT-SSX2 fusion gene. Seven sarcomas were high-grade and four of intermediate grade malignancy. Follow-up data were available in 10 patients. In all but one case, tumour recurred or metastasized within the abdomen. The pelvic sarcomas also metastasized outside the abdomen. Eight of 10 patients (80%) died of disease with survival from 4 to 36 months (mean 17 months, median 18 months). Two patients were alive with disease at 43 and 48 months.

CONCLUSIONS

Synovial sarcomas rarely arise within the abdomen and pelvis. They occur mainly in middle age, attain a large size, are difficult to excise and recur locally. Pelvic tumours metastasize distantly. Retroperitoneal tumours remain confined to the abdomen and, unlike synovial sarcomas elsewhere, do not metastasize remotely, although mortality is high.

The diagnostic utility of immunohistochemistry in distinguishing between mesothelioma and renal cell carcinoma: A comparative study

Both mesotheliomas and renal cell carcinomas can present a wide variety of morphological patterns. Because of this, renal cell carcinomas that metastasize to the pleura and lung may be confused with mesotheliomas. The aim of the present study was to compare the value of the various immunohistochemical markers currently available for the diagnosis of mesothelioma and renal cell carcinoma. A total of 48 mesotheliomas (40 epithelioid, 8 sarcomatoid), and 48 renal cell carcinomas (24 conventional, 12 chromophobe, 8 papillary, 4 sarcomatoid) were investigated for the expression of the following markers: calretinin, mesothelin, cytokeratin 5/6, WT1, thrombomodulin (TM), N-cadherin, CD15 (leu-M1), MOC-31, Ber-EP4, BG-8 (Lewis(y)), CD10, renal cell carcinoma marker (RCC Ma), carcinoembryonic antigen (CEA), and B72.3. All (100%) of the epithelioid mesotheliomas reacted for calretinin, mesothelin, and cytokeratin 5/6; 93% for WT1; 78% for TM; 75% for N-cadherin, 48% for CD10, 15% for Ber-EP4, 8% for MOC-31, 8% for RCC Ma, 5% for BG-8, and none for CEA, B72.3, or CD15. Of the sarcomatoid mesotheliomas, 88% expressed calretinin, 75% N-cadherin, 38% CD10, and 13% each expressed cytokeratin 5/6, WT1, and TM. All of the remaining markers were negative. Among the RCCs, 81% expressed CD10, 75% N-cadherin, 63% CD15, 50% RCC Ma, 50% MOC-31, 42% Ber-EP4, 8% BG-8, and 2% TM. The remaining markers were negative. The results indicate that calretinin, mesothelin, and cytokeratin 5/6 are the best positive mesothelioma markers for differentiating epithelioid mesotheliomas from renal cell carcinomas. The best discriminators among the antibodies considered negative markers for mesothelioma are CD15, MOC-31, and RCC Ma. An accurate differential diagnosis can be reached with the use of any 2 of the 3 recommended positive markers, which should be selected based on availability and on which ones yield the best staining results in a given laboratory. One of the recommended negative markers may be added to the panel if deemed necessary. If confirmation of renal origin is needed, RCC Ma could be useful. Calretinin is the only marker that appears to have any utility in distinguishing between sarcomatoid mesotheliomas and sarcomatoid renal cell carcinomas.

Aberrant expression of tight junction-related proteins ZO-1, claudin-1 and occludin in synovial sarcoma: an immunohistochemical study with ultrastructural correlation

Synovial sarcoma demonstrates epithelial differentiation, either by light microscopy (biphasic synovial sarcoma) or by immunohistochemical/ultrastructural methods only (monophasic) and poorly differentiated synovial sarcoma. Although the glands of synovial sarcoma are known to have tight junction-like structures, far less is known about junction formation in the spindled component of synovial sarcomas. Additionally, it is unknown whether the tight junctions of synovial sarcoma are normally constituted. The tight junction is a multiprotein complex consisting of numerous proteins that include ZO-1, claudin-1 and occludin. A total of 35 cases of synovial sarcoma (13 biphasic, 14 monophasic and eight poorly differentiated) were immunostained for ZO-1, claudin-1 and occludin using commercially available antibodies, heat-induced epitope retrieval and standard avidin-biotin technique. When available, corresponding electron micrographs were reviewed. For five cases, the presence of either an SYT-SSX1 (three cases) or SYT-SSX2 (two cases) gene fusion was known. Positive cases showed particulate membrane staining. The glands of biphasic synovial sarcomas expressed ZO-1 (13/13), claudin-1 (12/13) and occludin (11/13) in a manner identical to normal glandular epithelia, at the apical portion of the lateral membrane. The spindle cells of biphasic synovial sarcomas showed abnormal circumferential membranous expression of ZO-1 (12/13), claudin-1 (6/13) and occludin (3/13). Monophasic synovial sarcomas expressed ZO-1 in a circumferential pattern (13/14) but less often claudin-1 (4/14) or occludin (3/14). Poorly differentiated synovial sarcomas expressed ZO-1 (8/8) and claudin-1 (6/8) but only rarely occludin (2/8). By electron microscopy, recognizable tight junctions were seen only in glands. No correlation was seen between histologic subtype or fusion type and expression of tight junction proteins. We conclude that the glands of biphasic synovial sarcomas show well-organized, true epithelial tight junctions. In contrast, the spindled cells of all synovial sarcomas show significant abnormalities in the expression and localization of tight junction proteins, suggesting partial and/or aberrant epithelial differentiation.

Cadherins in cancer

The presence of a functional E-cadherin/catenin cell-cell adhesion complex is a prerequisite for normal development and maintenance of epithelial structures in the mammalian body. This implies that the acquisition of molecular abnormalities that disturb the expression or function of this complex is related to the development and progression of most, if not all, epithelial cell-derived tumors, i.e. carcinomas. E-cadherin downregulation is indeed correlated with malignancy parameters such as tumor progression, loss of differentiation, invasion and metastasis, and hence poor prognosis. Moreover, E-cadherin has been shown to be a potent invasion suppressor as well as a tumor suppressor. Disturbed expression profiles of the E-cadherin/catenin complex have been demonstrated in histological sections of many human tumor types. In different kinds of carcinomas, biallelic downregulation of the E-cadherin gene, resulting in tumor-restricted decrease or even complete loss of E-cadherin expression, appears to be caused by a variety of inactivation mechanisms. Gene deletion due to loss of heterozygosity of the CDH1 locus on 16q22.1 frequently occurs in many carcinoma types. However, somatic inactivating mutations resulting in aberrant E-cadherin expression by loss of both wild-type alleles is rare and restricted to only a few cancer types. A majority of carcinomas thus seems to show deregulated E-cadherin expression by other mechanisms. The present evidence proposes transcriptional repression as a powerful and recurrent molecular mechanism for silencing E-cadherin expression. The predominant mechanisms emerging in most carcinomas are hypermethylation of the E-cadherin promoter and expression of transrepressor molecules such as SIP1, Snail, and Slug that bind sequence elements in the proximal E-cadherin promoter. Interestingly, complex differential expression of other cadherins seems to be associated with loss of E-cadherin and to reinforce effects of this loss on tumor progression. Multiple agents can upregulate and stabilize the E-cadherin/catenin complex. Especially for those tumors with transcriptional and thus reversible downregulation of E-cadherin expression, these drug agents offer important therapeutic opportunities.

Value of E-cadherin and N-cadherin immunostaining in the diagnosis of mesothelioma

Distinguishing between epithelioid mesothelioma and pulmonary adenocarcinoma involving the pleura can be difficult on routine histological preparations. This differential diagnosis can be greatly facilitated by using immunohistochemical markers. E-cadherin and N-cadherin are among the newly described markers that have been proposed as potentially useful in the diagnosis of mesothelioma. E-cadherin and N-cadherin are members of the cadherin family of calcium-dependent cell adhesion molecules that play an important role in the embryogenic development and maintenance of normal tissue. Although several investigations have indicated that immunostaining for these markers can be useful in discriminating between mesotheliomas and adenocarcinomas, others have not confirmed this observation. In an attempt to resolve this controversy, the present study investigated 31 epithelioid mesotheliomas and 29 pulmonary adenocarcinomas for E-cadherin and N-cadherin expression using the 5H9, HECD-1, and clone 36 anti-E-cadherin antibodies, and the 3B9 and clone 32 anti-N-cadherin antibodies. Among the mesotheliomas, 68% reacted with the clone 36, 52% reacted with the HECD-1, and 19% reacted with the 5H9 anti-E-cadherin antibodies, and 74% reacted with the 3B9 and 71% reacted with the clone 32 anti-N-cadherin antibodies. Of the adenocarcinomas, 93% stained with the clone 36, 90% reacted with the HECD-1, and 90% reacted with the 5H9 anti-E-cadherin antibodies, 45% reacted with the clone 32 and 34% reacted with the 3B9 anti-N-cadherin antibodies. Based on the frequent strong reactivity with adenocarcinomas but not with mesotheliomas, it is concluded that only the 5H9 anti-E-cadherin antibody may have some utility in discriminating between epithelioid pleural mesotheliomas and pulmonary adenocarcinomas. The causes of the disparate results reported in the literature on the value of E-cadherin and N-cadherin immunostaining in distinguishing between mesotheliomas and pulmonary adenocarcinomas are unclear, but a significant factor appears to be differences in the reactivity of the antibodies used.

Epithelioid sarcoma: new insights based on an extended immunohistochemical analysis

CONTEXT

Epithelioid sarcoma has a distinctive epithelioid phenotype and characteristically exhibits immunohistochemical reactivity for epithelial markers (keratins and epithelial membrane antigen) and mesenchymal markers (most notably vimentin and CD34). Antibodies to certain keratin subunits and other novel antigens now available to surgical pathologists have not been tested on a large number of cases.

OBJECTIVE

To assist in the differential diagnosis of epithelioid sarcoma and to help elucidate its histogenesis through an expanded immunohistochemical profile.

DESIGN

Immunohistochemical testing with diverse antibodies was performed on 95 archived epithelioid sarcomas including 73 classic and 22 histologically variant subtypes retrieved from the files of the Armed Forces Institute of Pathology.

RESULTS

Immunohistochemical reactivity (number positive/number of cases tested [percent positive], frequency of staining) included keratin 14 (31/64 [48%], variable), gamma-catenin (35/74 [47%], variable), keratin 5/6 (10/33 [30%], focal), calretinin (8/40 [20%], focal), keratin 20 (11/71 [15%], focal), p63 (3/20 [15%], focal), whereas 9 invasive cutaneous squamous cell carcinomas showed strong p63 positivity, epithelial-specific antigen (10/74 [14%], variable), CD117/Kit (5/37 [14%], focal), keratin 15 (3/23 [13%], rare cell), mesothelin (2/64 [3%], rare cell), and CD10 (1/41 [2%], rare cell). No reactivity was observed for keratins 2, 5, and 10.

CONCLUSIONS

Diagnostically, p63 and keratin 5/6 distinguish cutaneous squamous cell carcinoma (positive) from epithelioid sarcoma (usually negative). No single immunomarker was able to distinguish the main 4 histologic subtypes of epithelioid sarcoma, indicating that they are all histogenetically related lesions. The limited expression of specific keratin subtypes used in our study supports the notion that epithelioid sarcoma is a mesenchymal neoplasm capable of partial epithelial transformation.

The immunohistochemical diagnosis of mesothelioma: a comparative study of epithelioid mesothelioma and lung adenocarcinoma

A large number of immunohistochemical markers that can facilitate the distinction between epithelioid pleural mesotheliomas and pulmonary peripheral adenocarcinomas have recently become available. The aim of this study is to compare the value of these new markers with others that are already commonly used for this purpose and to determine which are, at present, the best for discriminating between these malignancies. Sixty epithelioid mesotheliomas and 50 lung adenocarcinomas were investigated for expression of the following markers: calretinin, cytokeratin 5/6, WT1, thrombomodulin, mesothelin, CD44S, HBME-1, N-cadherin, E-cadherin, MOC-31, thyroid transcription factor-1 (TTF-1), BG-8 (Lewisy), carcinoembryonic antigen (CEA), Ber-EP4, B72.3 (TAG-72), leu-M1 (CD15), CA19-9, epithelial membrane antigen (EMA), and vimentin. All (100%) of the mesotheliomas reacted for calretinin, cytokeratin 5/6, and mesothelin, 93% for WT1, 93% for EMA, 85% for HBME-1, 77% for thrombomodulin; 73% for CD44S, 73% for N-cadherin, 55% for vimentin, 40% for E-cadherin, 18% for Ber-EP4, 8% for MOC-31, 7% for BG-8, and none for CEA, B72.3, leu-M1, TTF-1, or CA19-9. Of the adenocarcinomas, 100% were positive for MOC-31, Ber-EP4, and EMA, 96% for BG-8, 88% for CEA, 88% for E-cadherin, 84% for B72.3, 74% for TTF-1, 72% for leu-M1, 68% for HBME-1, 48% for CD44S, 48% for CA19-9, 38% for mesothelin, 38% for vimentin, 30% for N-cadherin, 14% for thrombomodulin, 8% for calretinin, 2% for cytokeratin 5/6, and none for WT1. After analyzing the results, it is concluded that calretinin, cytokeratin 5/6, and WT1 are the best positive markers for differentiating epithelioid malignant mesothelioma from pulmonary adenocarcinoma. The best discriminators among the antibodies considered to be negative markers for mesothelioma are CEA, MOC-31, Ber-EP4, BG-8, and B72.3. A panel of four markers (two positive and two negative) selected based upon availability and which ones yield good staining results in a given laboratory is recommended. Because of their specificity and sensitivity for mesotheliomas, the best combination appears to be calretinin and cytokeratin 5/6 (or WT1) for the positive markers and CEA and MOC-31 (or B72.3, Ber-EP4, or BG-8) for the negative markers. An extensive and detailed review of the literature is also provided.