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E-cadherin and calretinin: a useful combination of immunochemical markers for differentiation between mesothelioma and metastatic adenocarcinoma.

AIMS: To assess the diagnostic accuracy of combinations of antibodies in the differential diagnosis of metastatic carcinomas and mesotheliomas in pleural lesions. METHODS AND RESULTS: The specificity and sensitivity of the commercially available antibodies Ber-EP4, MOC-31, CEA, B72.3, CD15, E-cadherin and calretinin were evaluated using an indirect immunoperoxidase staining technique. This technique was applied to formalin-fixed, paraffin-embedded tissue blocks of pleural lesions. Twenty-one patients with metastatic carcinoma (MC) and 20 patients with malignant mesothelioma (MM) were included. The combination E-cadherin/calretinin had the highest specificity (MC 100% and MM 91%) and sensitivity (MM 100% and MC 91%) considering both categories of tumours. CONCLUSIONS: The combination of E-cadherin/calretinin appears to be a suitable panel for distinguishing metastatic carcinomas and mesotheliomas in pleural lesions. The additional value of other markers is limited.

Adenocarcinoma↗

Calretinin expression in ameloblastomas.

AIMS: Calretinin is a 29-kDa calcium-binding protein which is expressed in the central and peripheral nervous systems as well as in many other normal and pathological human tissues. The objective of this study was to determine whether calretinin was expressed in the epithelium of ameloblastomas. METHODS AND RESULTS: Twenty-seven cases of unicystic ameloblastoma and 31 cases of solid and multicystic ameloblastoma were studied. Five-micron sections were immunohistochemically stained using either antiserum 7696 from Swant, or antiserum 18-0211 from Zymed with a standard ABC method. The results were identical with the two antisera. Positive staining was seen in 22 cases (81.5%) of unicystic ameloblastomas. This generally consisted of diffuse, intense nuclear and cytoplasmic staining of several cell layers of the more superficial cells both in the characteristic and nondescript areas of the cyst linings. In the solid and multicystic ameloblastomas, staining occurred in 29 (93. 5%) of the cases. The staining was almost always restricted to the stellate reticulum-like epithelium, was generally intense and diffuse in distribution. Areas of squamous metaplasia stained particularly intensely as did the cells surrounding micro- and macro-cysts. In both groups of lesions, most of the cases that did not stain were intensely inflamed. CONCLUSIONS: The biological significance of calretinin expression in ameloblastomas is not known and its use as a distinctive, specific immunohistochemical marker for ameloblastic tissues remains to be confirmed. However, the results of this study raise the possibility that calretinin may be an important diagnostic aid in the differential diagnosis of cystic and solid ameloblastic tumours.

Ameloblastoma↗

Primary malignant gonadal mesotheliomas and asbestos.

AIMS: The clinicopathological, immunohistochemical and aetiological aspects, with respect to asbestos, of seven primary gonadal mesotheliomas (three intratesticular, four ovarian) are described and compared. These tumours are extremely rare, poorly described and the knowledge of their natural history is very limited. METHODS AND RESULTS: The cases were collated from the UK Health and Safety Executive Mesothelioma Register over a 24-year period (1968-91). Primary mesotheliomas of the tunica vaginalis and ovary comprised 0. 09% (10 cases) and 0.03% (three cases) of mesothelioma deaths, respectively. No primary intratesticular (non-tunica vaginalis) malignant mesotheliomas have been described. In this study, we present seven (three intratesticular, four ovarian) primary malignant gonadal mesotheliomas. In both genders the tumours show a similar age distribution (with median onset in the sixth decade), a similar association with asbestos (in approximately 50% cases), a diverse histological spectrum (with predominantly tubulopapillary epithelial subtype tumours) and an immunophenotype that is comparable with malignant pleural and peritoneal mesothelioma. The clinical course appears variable (mean, 26 months; range, 9-50 months). All tumours in the study presented as localized masses and their prognosis appeared more favourable than that of diffuse pleural and peritoneal cases. CONCLUSIONS: An awareness of the existence of these rare forms of malignant mesothelioma is important to prevent misdiagnosis. Immunohistochemistry has an important role in confirmation of the diagnosis. The accurate diagnosis of primary gonadal mesothelioma has potentially important medicolegal compensation considerations as a significant proportion of these cases are associated with asbestos.

Adult↗

Anti-mesothelial markers in sarcomatoid mesothelioma and other spindle cell neoplasms.

AIMS: To undertake a comparative evaluation of three antimesothelial markers (thrombomodulin, cytokeratin 5/6 and calretinin) with broad spectrum cytokeratin (AE1/AE3) in differentiating between sarcomatoid mesothelioma and a spectrum of spindle cell neoplasms. METHODS AND RESULTS: Thirty-one malignant sarcomatoid mesotheliomas were studied. Calretinin expression was focally identified in 12 (39%) tumours and thrombomodulin and cytokeratin 5/6 immunoreactivity was seen in nine (29%) cases. In comparison there was strong diffuse cytoplasmic reactivity with the broad spectrum cytokeratin (AE1/AE3) in 24 of 31 (77%) tumours. Thirty mixed spindle cells neoplasms were studied. No calretinin expression was identified in any case. Thrombomodulin immunoreactivity was identified in four (16%) cases (two angiosarcomas, two high-grade sarcomas, not otherwise specified). Cytokeratin 5/6 expression was seen in one high-grade pulmonary sarcoma originally termed malignant fibrous histiocytoma. None of the antimesothelial markers was expressed in the four spindle cell carcinomas studied. In contrast, broad spectrum cytokeratin was diffusely expressed in all four spindle cell carcinomas (three pulmonary, one renal), both synovial sarcomas, both malignant mixed Müllerian tumours, one of three pulmonary leiomyosarcomas and two of nine sarcomas, not otherwise specified. CONCLUSIONS: Immunohistochemistry has a more limited role in the diagnosis and distinction of sarcomatoid mesothelioma from other spindle cell neoplasms. The combination of a broad spectrum cytokeratin with calretinin combines both high sensitivity (77% for AE1/AE3) with high specificity (100% for calretinin) for sarcomatoid mesothelioma and can be diagnostically useful. The mesothelial markers, thrombomodulin and cytokeratin 5/6, are not useful alone in the diagnosis of sarcomatoid mesothelioma as each shows insufficient antibody sensitivity, although together they complement calretinin.

Biomarkers, Tumor↗

Use of calretinin in the differential diagnosis of unicystic ameloblastomas.

AIMS: Calretinin, a 29-kDa calcium-binding protein is expressed widely in normal human tissues and tumours including both unicystic and solid and multicystic ameloblastomas. The histological distinction between unicystic ameloblastomas and certain non-neoplastic odontogenic cysts can be problematic. The objective of this study was to determine whether calretinin was expressed in the lining epithelium of odontogenic keratocysts, residual and dentigerous cysts and to determine whether this calcium-binding protein could be used to distinguish these cysts from the unicystic ameloblastoma. METHODS AND RESULTS: The lining epithelium in 22 cases of odontogenic keratocyst, 26 cases of residual cyst and 20 cases of dentigerous cyst were examined for the expression of calretinin. No positive epithelial staining was observed in any of these cystic lesions. In comparison, however, 81.5% of cases of unicystic ameloblastoma showed a coarse dark brown staining of the more superficial epithelial cell layers. Scattered positive stromal and epithelial cells were present; these were interpreted as mast cells. CONCLUSIONS: Calretinin appears to be a specific immunohistochemical marker for neoplastic ameloblastic epithelium and we suggest that it may be an important diagnostic aid in the differential diagnosis of cystic odontogenic lesions and ameloblastic tumours.

Ameloblastoma↗

Immunohistochemical staining for calretinin is useful in the diagnosis of ovarian sex cord-stromal tumours.

AIMS: Ovarian sex cord-stromal tumours are a heterogeneous group of neoplasms which may be confused morphologically with a wide variety of tumours. Calretinin positivity has previously been demonstrated in a small number of ovarian sex cord-stromal tumours. The aim of this study was to investigate calretinin staining in a series of these tumours and their histological mimics in order to determine the value of calretinin staining in a diagnostic setting. METHODS AND RESULTS: Seventy-two neoplasms, including 37 ovarian sex cord-stromal tumours and 35 miscellaneous neoplasms which may enter into the differential diagnosis, were stained with a commercially available polyclonal antibody against calretinin. All sex cord-stromal tumours exhibited positivity except for a single fibrothecoma. In this group of tumours staining was generally diffuse and strong. Small numbers of the miscellaneous group of neoplasms exhibited positivity but this tended to be focal and weak, although this was not always the case. There was consistent strong positive staining of granulosa cells in follicular cysts and corpora lutea. There was also positive staining of luteinized stromal cells in two cases of ovarian stromal hyperplasia and hyperthecosis. CONCLUSIONS: Calretinin is a sensitive immunohistochemical marker of ovarian sex cord-stromal tumours and may be useful in a diagnostic setting. However, the value is somewhat limited since occasional neoplasms which enter into the morphological differential diagnosis may be positive. Be that as it may, calretinin positivity may be of value in the diagnosis of an ovarian sex cord-stromal tumour and its differentiation from other neoplasms. In this regard, calretinin should always be used as part of a larger panel.

Adolescent↗

Prichard's structures of the fossa ovalis are not histogenetically related to cardiac myxoma.

AIMS: Cardiac myxomas are neoplasms of unknown histogenesis. They are thought to arise from hypothetical subendothelial vasoformative reserve cells or from primitive cells which reside in the fossa ovalis and surrounding endocardium. In 1951 Prichard described a kind of microscopic endocardial structure with a predilection for the interatrial septum, which were suggested to be related to cardiac myxomas. To confirm the existence of Prichard's structures and to clarify their role in the genesis of cardiac myxomas, we examined histologically the fossa ovalis and we performed an immunohistochemical study of the endocardial abnormalities that were found. METHODS AND RESULTS: A prospective histological study of 100 interatrial septa and an immunohistochemical study of three out of the 12 endocardial abnormalities that were detected, as well as of four conventional cardiac myxomas were accomplished. Antibodies were used to vimentin, CD31, CD34, alpha-smooth muscle actin, S100 protein, thrombomodulin, calretinin and c-kit (CD117), a tyrosine kinase growth factor receptor for stem cell factor usually expressed by embryonic/fetal endothelium. Structures similar to the ones described by Prichard were found in 12% of septa, most of them in the left side of the fossa ovalis. The hearts with these structures were from patients 10 years older than the ones without them (72 +/- 10 versus 62 +/- 16 years, P=0.006). Immunohistochemically the cells comprising Prichard's structures were positive for vimentin, CD31, CD34 and thrombomodulin, and negative for alpha-smooth muscle actin, S100 protein, calretinin and c-kit. Therefore these cells seem to be mature endothelial cells, but not primitive multipotential mesenchymal cells. Furthermore, these cells were not found in the atrial tissue from the bases of any of the conventional cardiac myxomas. CONCLUSIONS: Our study suggests that there is no apparent relation between Prichard's structures and cardiac myxomas, and that Prichard's minute endocardial deformities are age-related phenomena.

Actins↗

Malignant epithelioid mesothelioma: anti-mesothelial marker expression correlates with histological pattern.

AIMS: Malignant epithelioid mesothelioma shows marked cytoarchitectural diversity. The aim of the study was to evaluate how immunoreactivity with mesothelial markers related to histological pattern. METHODS AND RESULTS: Ninety-two cases of malignant epithelioid mesothelioma (60 pleural, 32 peritoneal) were examined and classified as exhibiting tubulopapillary, adenomatoid, solid, small cell or pleomorphic patterns. All cases were immunohistochemically stained with thrombomodulin, calretinin, CD44H, and cytokeratin 5/6. Cases of malignant mesothelioma exhibited a number of different histological forms. Immunohistochemical expression of each mesothelial marker tested was not homogeneous across different histological patterns of malignant epithelioid mesothelioma, even within the same tumour section. Calretinin (with nuclear expression) was identified to show the highest overall sensitivity and lowest range variation in staining (67% sensitivity in small cell areas to 100% expression in pleomorphic areas). Cytokeratin 5/6 and thrombomodulin yielded similar overall sensitivity. Thrombomodulin appeared to demonstrate higher sensitivity for small cell variant tumour (83% sensitivity). A notable advantage with cytokeratin 5/6 was that expression was more diffuse in nature rather than the focal membranous elaboration seen in thrombomodulin. The widest range of staining was seen in small cell mesothelioma (83% sensitivity with thrombomodulin to 17% sensitivity with cytokeratin 5/6) and in tubulopapillary areas (90% sensitivity with calretinin to 38% sensitivity with CD44H). CONCLUSIONS: Calretinin appears most useful and shows the highest overall sensitivity for malignant epithelioid mesothelioma, with good expression in areas displaying a tubulopapillary, adenomatoid, solid and pleomorphic pattern. For small cell mesothelioma, thrombomodulin appears to confer higher sensitivity and is advocated, in this setting, as the first line mesothelial marker. Cytokeratin 5/6 is a useful and easily interpretable mesothelial marker. CD44H is not of particular use in the diagnosis of malignant epithelioid mesothelioma. Accurate interpretation of immunohistochemistry in mesothelioma requires an awareness of the immunophenotypic heterogeneity identified in different histological forms of the tumour, and this is of particular importance in small biopsies.

Biomarkers↗

Value of mesothelial and epithelial antibodies in distinguishing diffuse peritoneal mesothelioma in females from serous papillary carcinoma of the ovary and peritoneum.

AIMS: To evaluate the role of mesothelial markers (calretinin, thrombomodulin, cytokeratin 5/6, and CD44H) and carcinoma markers (polyclonal and monoclonal carcinoembryonic antigen, Leu-M1, CA-125 and Ber-EP4) in distinguishing diffuse peritoneal malignant mesothelioma from primary serous papillary adenocarcinoma of the ovary and peritoneum. METHODS AND RESULTS: Paraffin-embedded formalin-fixed blocks from 32 diffuse peritoneal mesotheliomas of epithelial subtype (all females), 20 serous papillary ovarian carcinomas and three primary peritoneal serous papillary carcinomas were studied. Calretinin and Ber-EP4 appeared to be the best positive mesothelial and carcinoma marker, respectively. Nuclear calretinin expression was identified in 28 of 32 malignant mesotheliomas with no nuclear immunoreactivity in the cohorts of serous papillary ovarian and peritoneal carcinomas, thus yielding 88% sensitivity and 100% specificity. Ber-EP4 showed 95% sensitivity and 91% specificity for serous papillary ovarian carcinoma. Thrombomodulin, cytokeratin 5/6 and CD44H immunoreactivities were seen in 18 (56%), 17 (53%) and 15 (47%) of peritoneal mesotheliomas, respectively, and in six (30%), five (25%) and five (25%) of the ovarian tumours, respectively. None of the three primary peritoneal serous papillary carcinomas expressed calretinin, thrombomodulin, cytokeratin 5/6 or CD44H. Polyclonal and monoclonal CEA, and Leu-M1 were expressed by two (10%), one (5%) and seven (35%) serous papillary ovarian carcinomas, respectively. None of the serous papillary peritoneal carcinomas expressed polyclonal CEA, monoclonal CEA or Leu-M1. CA-125 was positive in 19 (95%) and two (67%) ovarian and peritoneal carcinomas, respectively, and in eight (25%) peritoneal mesotheliomas. CONCLUSIONS: Calretinin and Ber-EP4 are useful discriminant markers in distinguishing peritoneal mesothelioma in women from serous papillary ovarian and peritoneal carcinoma. The other mesothelial markers (thrombomodulin, cytokeratin 5/6, and CD44H) and carcinoma markers (polyclonal and monoclonal CEA, and Leu-M1) yielded a too low sensitivity for practical use.

Antigens, Neoplasm↗

Malignant deciduoid mesothelioma of the pleura: report of two cases with long survival.

AIMS: To present two rare cases of malignant mesotheliomas with deciduoid features arising in the pleura, both with long survival. METHODS AND RESULTS: These two cases of deciduoid mesotheliomas were observed in adult patients (one 73-year-old male and one 23-year-old female). Only the male had a history of occupational asbestos exposure, whereas the woman had a history of familial mesothelioma. A deciduoid morphology was predominant and focal areas with tubular-papillary features were noted. The tumour cells were positive for cytokeratins, HMBE-1, calretinin, EMA and mitochondrion antibodies. The follow-up data did not suggest a particularly poor prognosis; the mean survival observed was 23 months (17 and 39 months, respectively). CONCLUSIONS: This deciduoid mesothelioma histological subtype does not appear to represent an unfavourable prognostic category.

Adult↗

Primary thymic epithelial tumours of the pleura mimicking malignant mesothelioma.

AIMS: To illustrate the macroscopic, light microscopic and immunophenotypic similarities that exist between primary pleural thymic epithelial tumours and diffuse malignant mesothelioma. To investigate the expression of the mesothelial markers, cytokeratin (CK) 5/6, calretinin and thrombomodulin in a series of mediastinal thymic epithelial tumours. METHODS AND RESULTS: Over a 10-year period, 64 diffuse pleural tumours of non-mesothelial histogenesis were identified in the files of referrals to the South Wales regional thoracic centre (Llandough Hospital, Cardiff). Of these, five pleural tumours were diagnosed as primary pleural thymic epithelial neoplasms. From the files of the Mesopath group, Caen, three additional cases of thymic epithelial tumours with pleural involvement were identified. The study group comprised eight cases (four males, four females) with median age at presentation of 56 years (range 19-75 years). In one case there was a history of asbestos exposure. Macroscopically, seven tumours formed diffuse pleural masses. No mediastinal abnormality or intraparenchymal lesions were seen in five cases. By light microscopy, seven thymic epithelial neoplasms showed a lobulated architecture, one appeared extensively cystic. The tumours were of varied morphological subtypes: one medullary (WHO Type A), two mixed (WHO Type AB), three predominantly cortical (WHO Type B1) and two cortical (WHO Type B1). The subtypes morphologically mimicked sarcomatoid, biphasic, lymphohistiocytoid variant and epithelioid mesothelioma. The pleural thymic epithelial tumours showed immunoreactivity with broad spectrum cytokeratin AE1/AE3 (8/8; 100%), CK5/6 (8/8; 100%), and 1/8 (13%) expressed thrombomodulin. Calretinin showed variable nuclear and cytoplasmic expression in all cases, but equivocally in the thymic epithelial cell component. In 7/8 (88%) the thymic epithelial cells exhibited focal aberrant expression of CD20. Epithelial membrane antigen (EMA) showed focal expression in the perivascular and organoid areas in 6/8 (75%) cases. Carcinoembryonic antigen (CEA) and CD34 were uniformly negative. In 4/8 (50%) cases the lymphoid cell component was of immature phenotype expressing CD99, terminal deoxynucleotidyl transferase (TdT) and lymphoid precursors had a high proliferation fraction with Ki67. In the series of 20 primary mediastinal thymic epithelial tumours tested, mesothelial marker expression revealed CK5/6 (20/20), thrombomodulin (3/20; 15%) and calretinin (0/20; 0%). Varying amounts of calretinin-positive stromal cells were present. CONCLUSION: Primary pleural thymic epithelial tumours are rare but may mimic malignant mesothelioma by forming diffuse serosal-based masses. In addition, both tumours may show morphological diversity (with epithelial, spindled and mixed components present). An awareness that thymic epithelial tumours may variably express the mesothelial markers CK5/6, calretinin and thrombomodulin prevents misdiagnosis. In the distinction from malignant mesothelioma a lobulated architecture and organoid features favour a thymic epithelial neoplasm. The presence of aberrant CD20 expression in a cytokeratin-positive epithelial neoplasm and/or the presence of an immature lymphoid population (by demonstration of CD1a, CD2, CD99 and TdT) indicates a thymic epithelial neoplasm. In contrast, nuclear calretinin expression favours malignant mesothelioma.

Adult↗

'Pseudomesotheliomatous' carcinomas of the pleura: a 10-year analysis of cases from the Environmental Lung Disease Research Group, Cardiff.

AIMS: To undertake a clinicopathological study of diffuse serosal neoplasms of epithelial histogenesis which clinically and pathologically mimic malignant pleural mesothelioma. METHODS AND RESULTS: Over a 10-year (1990-2000) study period 53 carcinomas mimicking diffuse pleural mesothelioma ('pseudomesotheliomatous' carcinoma) were identified. The study group comprised 50 men and three females, age range 33-77 (median 68) years. In 46 (87%) cases there was a history of smoking and in 40 (76%) cases a history of asbestos exposure. Histologically the pleural 'pseudomesotheliomatous' carcinomas could be divided into two broad groups: primary pulmonary carcinomas with florid pleurotropic growth (n = 47), of which 34 (70%) were adenocarcinomas; and diffuse carcinomatous involvement of the pleura by metastatic tumour (n = 6). This latter group comprised two transitional cell carcinomas of bladder, one renal (clear) cell carcinoma, one ductal pancreatic adenocarcinoma, one prostatic adenocarcinoma and one squamous cell carcinoma of parotid gland origin. Follow-up data were available in 35 cases. Regardless of tumour type, survival was poor (median 8 months) and comparable to diffuse pleural mesothelioma. CONCLUSIONS: Pleural 'pseudomesotheliomatous' carcinomas are uncommon (comprising 6% of referrals), pathologically heterogeneous tumours with poor prognosis. Tissue diagnosis should be obtained in all cases of suspected diffuse pleural neoplasia. By light microscopy and immunophenotype many of the tumours mimicked malignant mesothelioma. In particular, an awareness that all neoplasms exhibiting squamous differentiation may express cytokeratin 5/6 and thrombomodulin is important to prevent misinterpretation. In this respect, calretinin is regarded as the most specific and sensitive mesothelial marker. Misdiagnosis may have medico-legal implications in asbestos-related compensation claims.

Adenocarcinoma↗

CD10 and calretinin staining of endocervical glandular lesions, endocervical stroma and endometrioid adenocarcinomas of the uterine corpus: CD10 positivity is characteristic of, but not specific for, mesonephric lesions and is not specific for endometrial stroma.

AIMS: In the female genital tract CD10 has been used to assist in the evaluation of mesenchymal tumours of the uterus and in determining whether endometrial stroma is present. CD10 positivity has also been shown in cervical mesonephric remnants and this antibody has been suggested as a useful immunohistochemical marker of mesonephric lesions in the female genital tract. Calretinin has also been shown to be positive in mesonephric lesions. In this study the specificity of these two antibodies in evaluating cervical and uterine glandular lesions and the value of CD10 in determining whether stroma is endometriotic or not were investigated. METHODS AND RESULTS: Cases of cervical tubo-endometrial metaplasia (TEM) (n = 11), microglandular hyperplasia (MGH) (n = 10), endometriosis (n = 8), mesonephric remnants/hyperplasia (n = 12), endocervical adenocarcinoma, usual type (n = 15), mucinous variant of minimal deviation adenocarcinoma (MDA) (n = 7) and mesonephric adenocarcinoma (n = 3) were stained with antibodies against CD10 and calretinin. Nine cases of endometrial adenocarcinoma of endometrioid type were also stained. In all the cervical cases normal endocervical glands were negative with both antibodies except for one case with strong positive luminal staining with CD10. All cases of TEM, MGH and endometriosis were negative with CD10 and calretinin except for focal staining with CD10 in one case each of MGH (cytoplasmic staining) and endometriosis (luminal staining). Most usual endocervical adenocarcinomas were negative with both antibodies, although one exhibited focal cytoplasmic staining with calretinin and five exhibited limited luminal positivity with CD10. All MDAs were negative with both antibodies. Ten of 12 mesonephric remnants/hyperplasia showed luminal positivity with CD10 and one exhibited cytoplasmic and nuclear staining with calretinin. Two of three mesonephric adenocarcinomas showed luminal positivity with CD10 and nuclear and cytoplasmic positivity with calretinin. Seven of nine endometrial adenocarcinomas were positive with CD10 (four cytoplasmic, two membranous and cytoplasmic, one luminal and cytoplasmic) and three with calretinin (two cytoplasmic, one nuclear and cytoplasmic). Positive staining of endometriotic stroma with CD10 was present in all endometriosis cases but normal cervical stroma was also strongly positive, especially around glands. Endometriotic stroma and cervical stroma were negative with calretinin. CONCLUSIONS: We conclude that most endocervical glandular lesions, including mesonephric remnants/ hyperplasia, are negative with calretinin. However, the focal nuclear and cytoplasmic positivity with calretinin in two of three mesonephric adenocarcinomas suggests that this may be a useful indicator of a mesonephric origin of a cervical adenocarcinoma. Most mesonephric remnants/hyperplasias exhibit luminal positivity with CD10, although this is not invariable and staining is usually focal. Positive luminal staining of a benign endocervical glandular lesion with CD10 may help confirm mesonephric remnants. Although positive staining with CD10 was found in two of three mesonephric adenocarcinomas, the observed immunoreactivity of several conventional cervical adenocarcinomas limits the diagnostic value of CD10 in confirming a mesonephric origin for an adenocarcinoma. Since all cervical MDAs were negative with CD10, positivity with this antibody may be of value in distinguishing mesonephric hyperplasia from MDA, although this distinction rarely necessitates immunohistochemistry. Most endometrial adenocarcinomas of endometrioid type stain with CD10 and thus positivity with this antibody is not specific for a mesonephric origin of an endometrial adenocarcinoma. Positivity of normal cervical stroma limits the value of CD10 staining in confirming a diagnosis of cervical endometriosis.

Biomarkers, Tumor↗

Correlation of electrophysiology, neurochemistry and axonal projections of guinea-pig sphincter of Oddi neurones.

Sphincter of Oddi (SO) ganglia are comprised of two main types of neurones based either on their electrical or neurochemical properties. This study investigated whether any correlation exists between the electrical and neurochemical properties of these cells. SO neurones were characterized electrically as either Tonic or Phasic cells, labelled with neurobiotin, fixed, and processed for beta-nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-DA) staining and choline acetyltransferase immuno-reactivity to identify whether electrically characterized neurones were nitrergic or cholinergic. A total of 119 cells were analysed in this manner; 45% of cells were Tonic and 37% were Phasic. An equivalent number of Tonic (58.1%, 18/31) and Phasic cells (60%, 21/35) were choline acetyltransferase (ChAT) positive. Three of 34 Phasic cells were NADPH-DA positive, whereas 11/33 Tonic cells were NADPH-DA positive. In none of the preparations was ChAT immunoreactivity and NADPH-DA reactivity ever observed in the same neurone. Calretinin immunoreactivity was present in a subpopulation of both Tonic and Phasic neurones. No correlation was observed between the direction of axon projections and the electrophysiological or neurochemical properties of the cell. These results suggest that there is a lack of correlation between the electrical properties and the neurochemical content of SO neurones. Various explanations for these findings are discussed.

Animals↗

Expression of genes coding for proteoglycans and Wilms' tumour susceptibility gene 1 (WT1) by variously differentiated benign human mesothelial cells.

Mesothelial cells are of mesenchymal origin, although they also have epithelial characteristics. Such cells obtained from benign effusions are not terminally differentiated and can be kept in short-term cultures. These cultures grow with an either epithelial or fibroblast-like phenotype, a pattern which is stable through the early passages. Several factors have been associated with mesothelial differentiation. The Wilms' tumour susceptibility gene 1 (WT1) is expressed during transitions of mesenchyme to epithelial tissues, as in the embryonic kidney, and it has been suggested as a marker for the mesothelial lineage. The proteoglycans (PGs) and hyaluronan are also differentially synthesised by epithelial and fibroblastic malignant mesothelioma cells and the cell surface PGs seem to indicate phenotypic differentiation even in epithelial tumours. To investigate how the epithelial and fibroblast-like differentiation of benign mesothelial cells was correlated to WT1, PGs and hyaluronan synthase, we studied their expression by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) analyses. The expressions of these genes were all associated with a variation in phenotypic differentiation. Cell lines with epithelial morphology expressed more mRNA coding for WT1 and cell surface PGs than did the fibroblastic ones, the difference being greatest for syndecan-4 and glypican. The increase in WT1-associated mRNA was about as great as that of syndecans. Fibroblast-like cells, on the other hand, expressed substantially more of the matrix PGs versican and biglycan, while decorin expression was detected in only trace amounts in both morphological phenotypes. Hyaluronan synthase varied individually between the cell lines, although epithelial cells often expressed higher levels. The results indicate that the regulation of mesothelial differentiation is multifactorial and also involves WT1 and several PGs.

Actins↗

Synaptic loss reflected by secretoneurin-like immunoreactivity in the human hippocampus in Alzheimer's disease.

Secretoneurin is a recently described peptide derived by endoproteolytic processing from secretogranin II, previously named chromogranin C. In this study, we have investigated the distribution of secretoneurin-like immunoreactivity in the human hippocampus in controls and in Alzheimer's disease patients, and compared the staining pattern to that of calretinin. Secretoneurin-like immunoreactivity is present throughout the hippocampal formation. At the border of the dentate molecular layer and the granule cell layer, a band of dense secretoneurin immunostaining appeared. In this part, as in the area of the CA2 sector, the high density of secretoneurin-immunoreactivity coincided with calretinin-like immunoreactivity. The mossy fibre system displayed a moderate density of secretoneurin-immunoreactivity. In the entorhinal cortex, a particularly high density of secretoneurin-immunoreactivity was observed. The density of secretoneurin-like immunoreactivity was significantly reduced in the innermost part of the molecular layer and in the outer molecular layer of the dentate gyrus in Alzheimer's disease. For calretinin-like immunoreactivity, a less pronounced decrease was found in the innermost part of the molecular layer. About 40-60% of neuritic plaques were secretoneurin-immunopositive. This study shows that secretoneurin is distinctly distributed in the human hippocampus and that significant changes of secretoneurin-like immunoreactivity occur in Alzheimer's disease, reflecting synaptic loss.

Aged↗