Loss of bcl-2 expression in ductal carcinoma in situ of the breast relates to poor histological differentiation and to expression of p53 and c-erbB-2 proteins

Aim : This study (1) investigates the incidence of bcl-2 protein expression in a series of 108 cases of ductal carcinoma in situ (DCIS), including 25 with early invasive carcinoma, and (2) evaluates the relationship of bcl-2 expression to the histological grade of DCIS and to the expression of oestrogen receptor (ER), c-erbB-2 and p53 proteins.  

Methods and results

The expression of bcl-2, oestrogen receptor (ER), c-erbB-2 and p53 proteins was determined immunohistochemically. Cases were regarded as positive for individual antibodies when at least 10% of the DCIS cells showed positive staining. DCIS was graded histologically as well ( n  = 9), intermediately ( n  = 24), or poorly differentiated ( n  = 75). bcl-2 expression was documented in 57 cases (53%) and was strongly associated with the histological grade of DCIS ( P  < 0.0001). All cases of well-differentiated DCIS were bcl-2 positive and loss of bcl-2 expression was almost exclusively confined to poorly differentiated DCIS lesions. bcl-2 expression was also closely associated with positive ER status ( P  < 0.0001). Forty-seven of 57 (82%) bcl-2 positive cases were ER positive while 49/51 (96%) bcl-2 negative cases were ER negative. There was a significant inverse correlation between bcl-2 expression and both p53 protein expression ( P  = 0.0004) and c-erbB-2 expression ( P  < 0.0001). Nineteen of 24 (79%) p53 positive cases and 38/45 (84%) c-erbB-2 positive cases showed loss of bcl-2.  

Conclusions

Loss of bcl-2 expression occurs in poorly differentiated DCIS and is related to negative ER status and to positive p53 and c-erbB-2 status. This pattern of bcl-2 expression and its association with other biological markers in DCIS is similar to that reported in invasive breast carcinoma.     

Prognostic relevance of apoptotic cell death in non-Hodgkin's lymphomas: a multivariate survival analysis including Ki67 and p53 oncoprotein expression

Aims : To evaluate the independent prognostic value of apoptotic versus proliferative fractions in a series of 92 patients with non-Hodgkin's lymphomas (NHL).  

Methods and results

Apoptotic fractions were quantified by use of the TdT (terminal deoxynucleotidyl-transferase)-mediated in-situ end-labelling technique (TUNEL), the percentage of positive cells constituting the apoptotic index (AI). Proliferative rate was expressed as percentage of Ki67 positive cells (Ki67 LI). Tissues were also stained for p53 protein with the DO-1 antibody. Patients were followed up until death ( n  = 33) or for an average of 63 months ( n  = 56). AI increased with malignancy grade and proliferative activity but was not related to location, cell of origin, clinical stage, bone marrow involvement and p53 expression. In multivariate analysis, overall survival was independently influenced by grade, stage, p53 LI and chemotherapy. The independent predictors of disease-free survival were Ki67 LI location and chemotherapy. AI turned out to be the only independent (negative) predictor of post-relapse survival. On the other hand, a low Ki67 LI increased the risk of relapse (logistic regression analysis) whereas a low p53 LI increased the probability of complete response.  

Conclusions

Our results suggest that the combined assessment of apoptotic fraction, proliferative rate and p53 expression may provide important prognostic information independent of other clinicopathological parameters in NHL.     

Type 1 protein tyrosine kinases in benign and malignant breast lesions

Aims : To determine their significance, we examined the expression pattern of the four epidermal growth factor receptor (EGFR) family members as well as the phosphotyrosine kinase activity in breast tumour tissues.  

Methods and results

Fifty-three malignant breast tumours, four breast cancer cell lines, and 10 benign breast tumours were investigated. Fifty-three per cent (28/53) of the malignant tumours expressed EGFR protein, and the majority of these positive tumours were strongly positive. Eighty per cent (8/10) of the benign tumours also expressed EGFR protein, but all in a lower or moderate level. An association between EGFR expression and increasing malignancy grade was found in the group of infiltrating ductal carcinomas. Of the malignant tumours, 35.8% (19/53) expressed c-erbB-2 protein and 17% (9/53) c-erbB-3 protein, while no expression of c-erbB-2 and c-erbB-3 proteins was found in the benign tumours. Contrary to previous reports, we observed c-erbB-4 receptor protein to be less expressed in the malignant breast tumours. The 'normal' breast epithelial cells adjacent to the malignant tumours and the benign tumours demonstrated intensified membrane staining for c-erbB-4, while a number of the malignant tumours demonstrated a weak cytoplasmic staining or were negative. However, several malignant tumours with strong membrane staining for the c-erbB-4 protein were also found. No simple association between the expression of the four receptors and phosphotyrosine kinase activity was found.  

Conclusion

Our study has revealed a complex expression pattern of the EGFR family members in breast tumour cells. While the data about EGFR, c-erbB-2, c-erbB-3 and phosphotyrosine are largely in line with what has been reported, we found the c-erbB-4 protein expression to be decreased in the malignant tumours.     

Loss of basement membrane components laminin and type IV collagen parallels the progression of oral epithelial neoplasia

Aims : To determine the immunohistochemical localization of basement membrane components laminin and type IV collagen in premalignant and malignant lesions of the oral epithelium.  

Methods and results

Formalin-fixed tissue sections of 12 epithelial hyperplasias with no dysplasia and 30 dysplasias, clinically diagnosed as leukoplakia and/or erythroplakia, as well as 50 invasive squamous cell carcinomas, were stained with mouse monoclonal antibodies to human laminin and type IV collagen. Statistical analysis showed that there was a linear trend for discontinuous distribution of laminin from epithelial hyperplasia to epithelial dysplasia and invasive squamous cell carcinoma ( P  < 0.001). Laminin staining showed a linear trend for discontinuity with increasing grade of dysplasia ( P  < 0.05) and was more frequently discontinuous in areas of deep tumour invasion than in central or superficial areas ( P  < 0.05). Brush-shaped thickening and reduplication of the basement membrane were also identified.  

Conclusions

Alterations in the distribution of laminin and type IV collagen in oral premalignant and malignant lesions indicate that the loss of continuity of the subepithelial basement membrane parallels the progression of the neoplastic transformation process in oral epithelium.     

The extent of apoptosis is inversely associated with bcl-2 expression in premalignant and malignant breast lesions

 

Aims:

In this study we investigated the extent of apoptosis in benign, premalignant and malignant breast lesions and its association with the immunohistochemical expression of bcl-2 oncoprotein.  

Methods and results:

In order to detect apoptotic cells and bodies in tissue sections, the 3'-end DNA labelling method was used. Immunohistochemical staining was performed by using the avidin–biotin–peroxidase complex technique. A monoclonal antibody agains bcl-2 oncoprotein was used and the specificity of the antibody was confirmed by immunoblot analysis. According to the results the extent of apoptosis, as determined by the apoptotic index, was lowest in benign ductal hyperplasias and sclerosing adenoses (0.15% and 0.07%, respectively). It was moderately elevated in atypical hyperplasias and in-situ carcinomas (0.20% and 0.40%, respectively) and highest in invasive carcinomas (0.76%). In ductal invasive carcinomas, grade I lesions showed a lower apoptotic index (0.52%) than grade II (0.72%) and grade III (1.17%) carcinomas. The apoptotic index was not significantly lower in lobular (0.82%) than in ductal invasive carcinomas (0.85%). bcl-2 immunohistochemistry was inversely related to the apoptotic index. In all cases studied the inverse association was very strong ( P  = 0.0004) but it was also present when only carcinomas were analysed ( P  = 0.01). In benign and atypical hyperplasias, bcl-2 positivity was observed in all cases, but such cases were less frequent in in-situ lesions and in invasive carcinomas.  

Conclusions:

The results show that there is an inverse relationship between the extent of apoptosis and bcl-2 expression in breast lesions suggesting that its expression affects the regulation of apoptosis in them.     

Mucoepidermoid carcinoma arising in Warthin's tumour of the parotid gland: report of two cases with histopathological, ultrastructural and immunohistochemical studies

Aims : Malignant transformation of Warthin's tumour (WT) is a rare event. We present two cases of mucoepidermoid carcinoma (MEC) arising in WT in the parotid gland.  

Methods and results

Two cases of MEC arising in WT, which were found in 185 cases of WT of the parotid gland, were investigated by light and electron microscopy, and immunohistochemistry. Both cases had largely similar macroscopic and histological features with some differences. Histologically, the tumours consisted mainly of WT with multilayered hyperplastic arrangements of oncocytic cells and focal squamous and goblet cell metaplasia. In the same tumour mass, however, the features of MEC were observed with invasion to adjacent adipose tissue. A transitional zone between WT and MEC was evident. Both patients were alive and well without evidence of recurrence 30 and 34 months after surgery, respectively. Electron microscopy revealed that cyst lining epithelial cells in WTs had abundant mitochondria whereas some of the MEC cells contained numerous tonofilaments and mucinous granules. Immunohistochemically, oncocytic cells of WTs were strongly positive for mitochondria and Salyl-Tn was extensively stained in MECs. The labelling index for Ki67 was obviously higher in the carcinoma cells than the epithelial cells of WT.  

Conclusions

Our cases confirmed the possibility of malignant transformation of the epithelial component in WT to MEC.     

Apoptosis occurs more frequently in intraductal carcinoma than in infiltrating duct carcinoma of human breast cancer and correlates with altered p53 expression: detected by terminal-deoxynucleotidyl-transferase-mediated dUTP-FITC nick end labelling (TUNEL)

 

Aims:

We examined the relationship between apoptosis and three different major stages of human breast carcinoma: intraductal carcinoma (DCIS), infiltrating duct carcinoma (IDC) and metastatic carcinoma in lymph nodes. We also determined the correlation between apoptosis and oestrogen receptor (ER), progesterone receptor (PR) and p53.  

Methods and results:

The study investigates the extent of apoptosis in 63 breast carcinomas by in-situ end-labelling, in formalin-fixed, paraffin-processed tissue sections. The 63 breast carcinomas, included 22 DCISs, 26 IDCs, three infiltrating lobular carcinomas (ILC) and 12 metastatic lymph nodes. The apoptotic labelling index was higher in DCIS than IDC and metastatic carcinoma ( P  < 0.001, P  < 0.007, respectively). By immunohistochemistry, we also analysed p53, ER and PR. Apoptosis correlated significantly with p53 ( r  = 0.748, P  = 0.0004) in IDC. Also, ER correlated significantly with PR ( r  = 0.629, P  = 0.00001). No apparent correlation was found between the apoptosis and ER or PR.  

Conclusion:

Our data suggest that not only does apoptosis differ between intraductal carcinoma and infiltrating carcinoma but also it might be regulated by altered p53 expression.     

Breast development gives insights into breast disease

Aims : Studies of developing human breasts are essential for understanding the organogenesis as well as molecular pathogenesis of benign and malignant breast diseases. In this study we have examined the distribution of TGF-α, TGF-β1, tenascin-C and collagen type IV with the aim of starting to build a picture of the profile of molecules that may be involved in the development of the human breast.  

Methods and results

Ten fetal breasts (16 to 23 weeks of gestation) and 45 infant breasts, ranging in age from newborn to 2 years, were used in this study. Paraffin sections from these samples were immunostained with antibodies for these proteins and for Ki67 to elucidate the level of proliferative activity in different stages of breast development. TGF-α immunoreactivity was observed both in the stromal and the epithelial cells within fetal and infant breasts up to 25 days. TGF-β1 immunoreactivity was localized in the extracellular matrix. Tenascin-C was found around the neck of the developing breast bud and in the extracellular matrix of the infant with peaks in the newborn at 6–12 weeks. The immunoreactivity for type IV collagen was more intense in the region of the breast bud neck in the fetal breasts and reduced around the tips of lobular and terminal-end buds within the infant breasts.  

Conclusions

The distribution of the growth factors and extracellular matrix proteins within the developing human breast indicates that they play a significant role in different cellular compartments during morphogenesis and provides insights into breast disease.     

Stereological estimates of the nuclear/cytoplasmic ratio and star volume on fibreoptic biopsies are of prognostic value for survival in a preliminary study of advanced squamous cell carcinoma of the lung

 

Aims:

This study evaluated the role of morphometric and clinical parameters in establishing the prognosis of patients submitted to radiotherapy for advanced squamous cell carcinoma of the lung.  

Methods and results:

Morphometric studies were performed by point counting techniques. Forty patients were included in this study. Group 1 patients ( n  = 22) were those with survival equal to or less than 6 months; group 2 ( n  = 10) patients had a survival of 7 to 12 months; and group 3 ( n  = 8) included patients with survival greater than 12 months. To characterize these three groups of patients, models combining categorical and continuous variables were constructed by means of discriminant analysis. Weight loss, histological grade, nuclear/cytoplasmic ratio and star volume of the nuclei were selected during the backward procedure as relevant variables to characterize the three groups of patients. The overall sensitivity of the model was 90%.  

Conclusions:

Our results indicate that histopathological data may help to predict prognosis in patients with advanced squamous cell lung carcinoma, and encourage the use of morphometric procedures in histopathological analysis of this type of lung tumour.     

bcl-2 and p53 immunophenotypes in pre-invasive, early and advanced oesophageal squamous cancer

 

Aims:

An inverse correlation between bcl-2 and p53 expression has been reported in several types of epithelial tumour. The role of bcl-2 and p53 in the development of oesophageal squamous carcinoma has yet to be established. The expression of bcl-2 and p53 proteins has been evaluated in the multistage oesophageal tumorigenesis, which progresses from normal mucosa to dysplasia (squamous intraepithelial lesion, SIL), to invasive early and advanced oesophageal squamous cancer.  

Methods and results:

Sixty-four cases of squamous oesophageal cancer, coexisting with SIL in 18 cases, were immunohistochemically analysed for any overexpression of bcl-2 and p53 proteins. Any association of bcl-2 and p53 protein expression with patient survival was also analysed. We observed bcl-2 expression that decreased significantly during the progression of oesophageal carcinogenesis. A decreasing frequency in the expression of bcl-2 in advanced oesophageal squamous cancer coincided with frequent p53 overexpression. bcl-2 expression was correlated with patient survival by univariate analysis. The association disappeared after adjusting for tumour stage. p53 overexpression showed no association with patient survival by either univariate or multivariate analysis.  

Conclusions:

The down-regulation of bcl-2 and up-regulation of p53 in advanced oesophageal squamous cancer suggest that bcl-2 and p53 proteins may interact in the progression of oesophageal squamous cancer.     

Expression of c-Met correlates with grade of malignancy in human astrocytic tumours: an immunohistochemical study

 

Aims:

Recent studies suggest the involvement of hepatocyte growth factor/scatter factor (HGF/SF) in glioma cell invasion and tumour progression. We investigated the distribution and rate of tumour cells that express c-Met protein, which is the cell-surface receptor for HGF/SF, in astrocytic tumours. The type of cells that express c-Met in tumour tissues was also identified.  

Methods and results:

c-Met expression was screened immunohistochemically in a total of 43 astrocytic tumours, including 14 low-grade astrocytomas (A), 13 anaplastic astrocytomas (AA) and 16 glioblastoma multiforme (GBM). c-Met reactivity was demonstrated predominantly in the cytoplasm of tumour cells. Bizarre large tumour cells tended to stain intensely. Higher c-Met expression levels (≥ 2 +, more than 25% cells were positive) were noted in 21.4% of (A) vs. 53.8% in (AA) and 87.5% in (GBM) ( P  < 0.001), indicating a clear relationship between c-Met protein staining and higher grade astrocytic tumours. Moreover, c-Met immunoreactivity was also shown in tumour microvasculature, reactive astrocytes, and neurones in the cortex infiltrated by glioma cells. In 85.7% of cases containing infiltrated cortex, neurones were positive vs. no neurones in non-neoplastic regions ( P  < 0.002).  

Conclusions:

This evidence suggests that c-Met expression in the brain could be associated with astrocytoma progression and also reactive process. Immunohistochemical determination of c-Met-expressing cell types helps to understand possible roles of c-Met in tumour tissues.     

Apoptosis is associated with atypical or malignant change in meningiomas. An in situ labelling and immunohistochemical study

Aims : Although necrosis is an important phenomenon with implications for grading and prognostication in meningiomas, the alternate form of cell death, apoptosis, has not been extensively studied. In this series, we aimed to determine whether apoptosis in meningiomas correlated with histological types and grading. We also looked for a relationship between expression of apoptosis-related genes bcl-2 , p53 , c-myc and apoptosis in meningiomas.  

Methods and results

Fifty-one meningiomas of diverse histological subtypes and grades were investigated with in-situ end-labelling of DNA fragments as well as immunohistochemical analysis of three apoptosis-related genes: p53 , bcl-2 and c-myc . Our results showed that the apoptosis index was significantly higher in high-grade meningiomas (0.12%, n  = 12) in than the benign meningiomas (0.023%, n  = 39) ( P  = 0.001) but there was no difference among the different histological subtypes of the benign meningiomas ( P  = 0.125). There is no obvious relationship between p53, bcl-2 and c-myc staining and apoptosis index in this group of meningiomas.  

Conclusion

We conclude that apoptosis is an important phenomenon in meningiomas and that it is associated with atypical or malignant changes in meningiomas. Apoptosis in meningiomas has no clearcut relationship with expression of p53 , bcl-2 and c-myc .     

Down-regulation of CD95 (Fas/Apo-1) in the epithelia of adenovirus-infected appendices

 

Aims:

Adenoviral inclusions are commonly seen in appendices from infants with intussusception. They are associated with focal epithelial budding and less frequently with epithelial shedding. These morphological changes could depend on the opposing effects of adenoviral gene products on CD95-mediated apoptosis.  

Methods and results:

Appendices from intussusceptions with viral inclusions ( n  = 4) and normal appendices ( n  = 10) were studied by immunochemistry with anti-adenovirus, anti-CD95 and anti-HLA-DR antibodies. Apoptosis was studied by the TUNEL method. The mucosa of normal appendices contained no adenoviral protein. CD95 was present in all epithelial cells except Paneth cells. HLA-DR was absent in epithelial cells and apoptosis was seen only in germinal centres and in a few surface epithelial cells. The epithelium of appendices from intussusceptions contained nuclear inclusions labelled with anti-adenovirus antibody, always found in the epithelial buds. The epithelial CD95 pattern was drastically altered in adenovirus-infected appendices. CD95 was absent from the budding foci. In these foci, HLA-DR was overexpressed. There was also increased epithelial apoptosis in areas remote from those lacking CD95 antigen.  

Conclusions:

The appearance of epithelial budding or shedding in appendices from intussusception could be due to focal in situ differences in the expression of adenoviral genes.     

Mammary epidermoid inclusion cysts after wide-core needle biopsies

 

Aims:

To investigate the prevalence of squamous epidermoid inclusion cysts after wide-core needle biopsy.  

Methods and results:

Epidermoid inclusion cysts were found in five of 17 surgical excisions (29%) after preliminary wide-core needle biopsies in a 7-month period. Thereafter they were not seen in 26 subsequent postwide-core surgical excisions in a period of 6 months.  

Conclusions:

The cysts appear to be an iatrogenic complication of wide-core biopsy, and need morphological recognition in order to avoid confusion with spontaneous squamous metaplasia of benign or malignant breast epithelium. Longer term implications are unknown.     

Carcinosarcoma of the oesophagus showing neuroendocrine, squamous and glandular differentiation

 

Aim:

A case of oesophageal carcinosarcoma occurring in a previously fit, 64-year-old man is reported.  

Case summary:

The carcinomatous component displayed neuroendocrine, squamous and glandular differentiation; the sarcomatous component showed no specific features of differentiation. In-situ squamous carcinoma was present in the adjacent squamous mucosa. The most superficial part of the invasive tumour consisted of carcinosarcoma with a predominant neuroendocrine epithelial component. Squamous carcinoma without an accompanying sarcomatous component occupied most of the deeper part of the tumour, suggesting outgrowth of this tumour type by a selective growth advantage.  

Conclusion:

We speculate that further tumour growth might have led to complete replacement of the tumour by pure squamous carcinoma, and that other advanced oesophageal squamous carcinomas might have had their origin in a short-lived carcinosarcomatous phase.     

Multinucleated stromal giant cells of testis

 

Aims:

This study documents the frequency of multinucleated stromal giant cells within the interstitium of the testis and looks for possible aetiological reasons for this occurrence.  

Materials and methods:

We examined sections of testes from 150 unselected autopsy cases finding stromal giant cells in 43%. An aetiological association between the occurrence of multinucleated stromal giant cells in this site and hormonal or other pathogenetic influences could not be established.  

Conclusions:

In many instances, this occurrence appears to be an age related phenomenon.     

Intravascular lymphomatosis: a clinicopathological study of two cases presenting as an interstitial lung disease

 

Aims:

Intravascular lymphomatosis is an uncommon type of non-Hodgkin's lymphoma characterized by intravascular proliferation of neoplastic lymphoid cells. Although the tumour is basically a systemic disease, eventually involving multiple organs, primary presentation in the lung is rare.  

Methods and results:

We describe the clinicopathological features of two patients with intravascular lymphomatosis presenting in the lung. One patient complained of fever, headache and chest pain; the other, of dyspnoea on exertion and headache. Both patients showed reticulonodular density on chest radiography and decreased diffusion capacity. Lung biopsy showed features characteristic of intravascular lymphomatosis. Malignant lymphoid cells were CD30 positive T-cells of anaplastic large cell type in one patient and B-cells of large cell type in the other. There was a poor response to chemotherapy and both patients died of the disease within 3 months of diagnosis.  

Conclusions:

These cases and 10 previous reports illustrate the need to include intravascular lymphomatosis in the differential diagnosis of interstitial lung disease.     

Lesions of 13q may occur independently of deletion of 16q in spindle cell/pleomorphic lipomas

 

Aims:

Very recent multidisciplinary investigations have allowed for the definition among lipomas of a clinical and histological subtype called spindle cell and/or pleomorphic lipoma, possibly associated with partial monosomy 16 and anomalies of chromosome 13. In order to get nearer to the underlying critical molecular changes further multidisciplinary pathological and genetic research is indicated, to identify which chromosome(s) anomalies are crucial in the development of these tumours.  

Methods and results:

In an ongoing multidisciplinary study of lipomatous tumours, including clinical findings, morphology, histochemistry and cytogenetics, two instances were found of spindle cell lipoma with clonal chromosome changes. In both cases chromosome 13 was involved, whereas only one showed a partial monosomy 16.  

Conclusions:

Partial monosomy 16 is a characteristic lesion in spindle cell lipoma, usually associated with anomalies of chromosome 13. The present report confirming a previous single observation indicates, however, that lesions of 13 may occur independently from lesions of 16, suggesting different underlying molecular lesions in these otherwise very similar lipomas.     

Nasal T/NK cell lymphomas commonly express perforin and Fas ligand: important mediators of tissue damage

 

Aims:

Two molecular mechanisms of T/natural killer (NK) cell-mediated cytotoxicity, one perforin based and the other Fas based, have been demonstrated, and both systems induce cytotoxicity in the target cells. The Fas-based mechanism involves the transducing molecule Fas and its ligand (FasL). In addition, perforin and/or FasL are also expressed in the cytotoxic T/NK cells. This study was thus designed to investigate the Fas and perforin pathways of the cytotoxic T/NK lymphoma cells in the nasal cavity.  

Methods and results:

Eight patients with nasal lymphoma were analysed using immunohistochemical staining methods. Two cases were CD3+ CD56+ (T/NK cell) type, and six were CD3− CD56+ (NK cell) type. All cases showed Epstein–Barr virus genomes by in-situ hybridization. In addition, all cases showed the expression of TIA-1 (GMP-17), which is a marker of cytotoxic T and NK cells. FasL was expressed in the majority of the lymphoma cells and some histiocytes, while Fas was found in lymphoma cells and many non-neoplastic cells. In addition, the expression of perforin was detected in almost all lymphoma cells. In the double stainings, lymphoma cells expressed both FasL and perforin. Based on these findings, both the perforin- and Fas-based pathway of the cytotoxic T/NK lymphoma cells are thus considered to play an important role in the clinical features.  

Conclusions:

Tissue damage is a common morphological feature in nasal T/NK cell lymphoma. The above findings therefore support the theory that tissue damage is due to both the cytotoxicity of T/NK lymphoma cells as well as to angiocentricity.     

Synovial sarcoma of the pleura and its differentiation from other primary pleural tumours: a clinicopathological and immunohistochemical review of three cases

Aims : Synovial sarcomas are rare tumours occasionally arising in the pleural cavity, a site where their histological characteristics may be mistaken for those of malignant mesothelioma. We examined three cases of primary pleural synovial sarcoma in order to look for clinicopathological features that may help in distinguishing them from both mesotheliomas and other sarcomas that may arise in the pleura.  

Methods and results

All three patients were male, aged 42, 28 and 42, respectively, and had no known exposure to asbestos. One biphasic tumour contained neutral mucin in focal epithelial elements that also stained positively for BerEP4 and AUA1. All three tumours showed focal positivity for either keratin or EMA in the sarcomatous elements, and they also stained positively for bcl-2 protein and MIC2 gene product (CD99).  

Conclusions

Our results emphasize the importance of being aware of synovial sarcoma as a possible primary pleural malignancy, especially in a young patient with a localized mass. In addition, the presence of bcl-2 protein perhaps represents a useful marker in distinguishing synovial sarcoma, especially monophasic variants, from mesothelioma within a panel of antibodies.