Clinical and Genomic Characterization of Pancreatic Ductal Adenocarcinoma with Signet-Ring/Poorly Cohesive Cells

Signet-ring cell (SRC)/poorly cohesive cell carcinoma is an aggressive variant of pancreatic ductal adenocarcinoma (PDAC). This study aimed to clarify its clinicopathologic and molecular profiles based on a multi-institutional cohort of 20 cases. The molecular profiles were investigated using DNA and RNA sequencing. The clinicopathologic parameters and molecular alterations were analyzed based on survival indices and using a validation/comparative cohort of 480 conventional PDAC patients. The primary findings were as follows: (1) clinicopathologic features: SRC carcinomas are highly aggressive neoplasms with poor prognosis, and the lungs are elective metastatic sites; (2) survival analysis: a higher SRC component was indicative of poorer prognosis. In particular, the most clinically significant threshold of SRC was 80%, showing statistically significant differences in both disease-specific and disease-free survival; (3) genomic profiles: SRC carcinomas are similar to conventional PDAC with the most common alterations affecting the classic PDAC drivers KRAS (70% of cases), TP53 (55%), SMAD4 (25%), and CDKN2A (20%). EGFR alterations, RET::CCDC6 fusion gene, and microsatellite instability (3 different cases, 1 alteration per case) represent novel targets for precision oncology. The occurrence of SMAD4 mutations was associated with poorer prognosis; (4) pancreatic SRC carcinomas are genetically different from gastric SRC carcinomas: CDH1, the classic driver gene of gastric SRC carcinoma, is not altered in pancreatic SRC carcinoma; (5) transcriptome analysis: the cases clustered into 2 groups, one classical/exocrine-like, and the other squamous-like; and (6) SRC carcinoma-derived organoids can be successfully generated, and their cultures preserve the histologic and molecular features of parental SRC carcinoma. Although pancreatic SRC carcinoma shares similarities with conventional PDAC regarding the most important genetic drivers, it also exhibits important differences. A personalized approach for patients with this tumor type should consider the clinical relevance of histologic determination of the SRC component and the presence of potentially actionable molecular targets.

Extrahepatic Distal Cholangiocarcinoma vs. Pancreatic Ductal Adenocarcinoma: Histology and Molecular Profiling for Differential Diagnosis and Treatment

Pancreatic ductal adenocarcinoma (PDAC) and distal cholangiocarcinoma (dCCA) are very aggressive tumors with a high mortality rate. Pancreas and distal bile ducts share a common embryonic development. Hence, PDAC and dCCA exhibit similar histological features that make a differential diagnosis during routine diagnostic practice challenging. However, there are also significant differences, with potential clinical implications. Even if PDAC and dCCA are generally associated with poor survival, patients with dCCA seem to present a better prognosis. Moreover, although precision oncology-based approaches are still limited in both entities, their most important targets are different and include alterations affecting BRCA1/2 and related genes in PDAC, as well as HER2 amplification in dCCA. Along this line, microsatellite instability represents a potential contact point in terms of tailored treatments, but its prevalence is very low in both tumor types. This review aims at defining the most important similarities and differences in terms of clinicopathological and molecular features between these two entities, also discussing the main theranostic implications derived from this challenging differential diagnosis.

Genomic characterization of hepatoid tumors: context matters

Hepatoid tumors (HT) are rare neoplasms morphologically resembling hepatocellular carcinoma, which arise in several organs other than the liver. A comprehensive molecular profile of this group of neoplasms is still lacking. Genomic characterization of 19 HTs from different organs (three colon HTs, four esophagogastric HTs, four biliary HTs, six genitourinary HTs, two lung HTs) was performed using a multigene next-generation sequencing panel. NGS unraveled a composite molecular profile of HT. Their genetic alterations were clearly clustered by tumor site: (i) colorectal HT displayed microsatellite instability, high tumor mutational burden, mutations in ARID1A/B genes and NCOA4-RET gene fusion (2/3 cases); (ii) gastric HT had TP53 mutations (2/4); (iii) biliary HT displayed loss of CDKN2A (3/4) and loss of chromosome 18 (2/4); (iv) genital HT showed gain of chromosome 12 (3/6); (v) lung HT had STK11 somatic mutations (2/2). The only commonly mutated gene occurring in HT of different sites was TP53 (8/19 cases: colon 2, esophagogastric 2, biliary 2, genital 1, lungs 1). This study shows that most genetic alterations of HT were clustered by site, indicating that context matters. The novel potential targets for HT precision oncology are also clustered based on the anatomic origin. This study shed light on the biology of these rare cancers and may have important consequences for treatment decisions and clinical trial selection for HT patients.

Colorectal cancer with microsatellite instability: Right-sided location and signet ring cell histology are associated with nodal metastases, and extranodal extension influences disease-free survival

Colorectal cancer (CRC) with microsatellite instability (MSI) accounts for 15-18 % of all CRCs and represents the category with the best prognosis. This study aimed at determining any possible clinical/pathological features associated with a higher risk of nodal metastasization in MSI-CRC, and at defining any possible prognostic moderators in this setting. All surgically resected CRCs of the last 20 years (mono-institutional series) with a PCR-based diagnosis of MSI, with and without nodal metastasis, have been retrieved for histological review, which was performed following WHO guidelines. Furthermore, the most important prognostic moderators have been investigated with a survival analysis. The study of 33 cases of MSI-CRCs with nodal metastasis highlighted a high fidelity of histology maintenance between primary tumors and matched nodal metastases. At survival analysis, the strongest prognostic variable in MSI-CRCs with nodal metastasis was the extranodal extension (multivariate analysis, HR: 14.4, 95 %CI: 1.46-140.9, p = 0.022). Furthermore, through a comparison between nodal positive (33 cases) and nodal negative (71 cases) MSI-CRCs, right-sided location (p < 0.0001), pT4 stage (p = 0.0004) and signet-ring histology (p = 0.0089) emerged as parameters more commonly associated with nodal metastasization. These findings shed new light on the biology of MSI-CRC and can be of help for the prognostic stratification of MSI-CRC patients.

High Diagnostic Accuracy of RT-QuIC Assay in a Prospective Study of Patients with Suspected sCJD

The early and accurate in vivo diagnosis of sporadic Creutzfeldt–Jakob disease (sCJD) is essential in order to differentiate CJD from treatable rapidly progressive dementias. Diagnostic investigations supportive of clinical CJD diagnosis include magnetic resonance imaging (MRI), electroencephalogram (EEG), 14-3-3 protein detection, and/or real-time quaking-induced conversion (RT-QuIC) assay positivity in the cerebrospinal fluid (CSF) or in other tissues. The total CSF tau protein concentration has also been used in a clinical setting for improving the CJD diagnostic sensitivity and specificity. We analyzed 182 CSF samples and 42 olfactory mucosa (OM) brushings from patients suspected of having sCJD with rapidly progressive dementia (RPD), in order to determine the diagnostic accuracy of 14-3-3, the total tau protein, and the RT-QuIC assay. A probable and definite sCJD diagnosis was assessed in 102 patients. The RT-QuIC assay on the CSF samples showed a 100% specificity and a 96% sensitivity, significantly higher compared with 14-3-3 (84% sensitivity and 46% specificity) and tau (85% sensitivity and 70% specificity); however, the combination of RT-QuIC testing of the CSF and OM samples resulted in 100% sensitivity and specificity, proving a significantly higher accuracy of RT-QuIC compared with the surrogate biomarkers in the diagnostic setting of patients with RPD. Moreover, we showed that CSF blood contamination or high protein levels might interfere with RT-QuIC seeding. In conclusion, we provided further evidence that the inclusion of an RT-QuIC assay of the CSF and OM in the diagnostic criteria for sCJD has radically changed the clinical approach towards the diagnosis.

Expression of Circulating miR-17-92 Cluster and HDAC9 Gene in Atherosclerotic Patients with Unstable and Stable Carotid Plaques

AIMS

The miR-17-92 cluster and the HDAC9 gene are involved in inflammatory, apoptotic, and angiogenic processes that are activated in the vulnerable carotid plaque. The aim of this research was to determine whether expression of one or more of the miRs of the miR-17-92 cluster and/or HDAC9 expression could represent biomarkers for patients with unstable atherosclerotic carotid plaques.

MATERIALS AND METHODS

Plasma levels of miRs and HDAC9 expression in peripheral blood were analyzed by real-time PCR in patients with histologically classified stable or unstable plaques.

RESULTS

No differences were observed between the two groups.

DISCUSSION AND CONCLUSIONS

Levels of the miR-17-92 cluster in plasma and HDAC9 gene expression in peripheral blood cannot be considered appropriate biomarkers to identify patients with unstable plaques at risk of rupture.

Immunohistochemical detection of arginine methylated proteins (MeRP) in archival tissues

AIMS

To (i) determine whether methylarginine-specific antibodies can be employed for standard immunohistochemical analysis of paraffin-embedded tissues, (ii) analyse methylarginine expression in normal and neoplastic tissues and (iii) correlate methylarginine expression with that of protein arginine methyltransferase (PRMT1), the predominant cellular arginine methyltransferase.

METHODS AND RESULTS

Immunohistochemistry of normal and cancer tissues was performed utilizing three commercial polyclonal antibodies: anti-methylarginine-specific antibody (anti-mRG) raised against a methylarginine peptide, Control antibody (anti-RG), a control antiserum raised against a corresponding arginine peptide without any methylated residues and anti-PRMT1. Nuclear and/or cytoplasmic methylarginine expression was detected in all keratinized and non-keratinized epithelia. A preliminary survey of a series of thyroid, pancreatic, colonic and gastric cancers identified a different pattern of methylarginine expression in comparison with normal tissue. A correlation between methylarginine staining and PRMT1 expression was found in all normal and cancer tissues analysed.

CONCLUSION

Methylarginine-specific antibodies are capable of recognizing methylarginine proteins (MeRP) in paraffin-embedded tissues. Methylarginine proteins are expressed widely and show differences in subcellular localization in various organs and neoplastic conditions. The efficient detection of methylproteins by standard immunohistochemistry provides a new tool to investigate the role of methylarginine proteins (MeRP) in biological processes including carcinogenesis.

Expression of transmembrane protein tyrosine phosphatase gamma (PTPgamma) in normal and neoplastic human tissues

AIMS

To establish the conditions for protein tyrosine phosphatase gamma (PTPgamma) detection in paraffin tissues using two antibodies raised against its NH(2)- (anti-P4) and COOH-termini (gammaTL1); to analyse its expression in normal tissues and to perform an initial screening of neoplastic tissues.

METHODS AND RESULTS

Membranous and/or cytoplasmic PTPgamma expression was detected in the majority of epithelial cell types and in endocrine cells, with the highest expression in adrenal medulla, endocrine cells of the gastrointestinal tract and pancreatic islets. Both antibodies stained the thyroid follicular epithelium, but only anti-P4 antibody stained the colloid matrix, suggesting shedding/secretion of the PTPgamma extracellular domain. Marked loss of PTPgamma immunoreactivity was detected in subsets of ovarian (21%), breast (56%) and lung (80%) neoplasms. Conversely, cytoplasmic positivity was found in 37% of lymphomas, mainly of high-grade histotypes, while normal lymphocytes were negative. Brain tissue showed PTPgamma expression in a few neuronal and glial elements and PTPgamma was overexpressed in the majority of high-grade astrocytomas.

CONCLUSIONS

We have analysed PTPgamma expression in archival paraffin-embedded tissues for the first time, demonstrating particularly high expression in endocrine cells and both down- and up-regulation in neoplasia, the latter possibly reflecting the undifferentiated state of the neoplastic cells, suggesting a complex role for this phosphatase.

Quantitative study of breast cancer progression: different pathways for various in situ cancers

The chromatin pattern in nuclei from breast ductal proliferative lesions was quantitatively evaluated with the objective of deriving measures of tumor progression. A total of 110 cases were analyzed. There were 38 cases of normal tissue or benign proliferative lesions, 41 cases of ductal carcinoma in situ (DCIS), and 31 cases of microinfiltrating DCIS and of infiltrating cancer. A total of 9424 nuclei were analyzed. High-resolution images were digitally recorded. For each nucleus, 93 karyometric features descriptive of the spatial and statistical distribution of the nuclear chromatin were computed. Data analysis included establishing a profile of relative deviations of each feature from "normal," called the nuclear signature, and of lesion signatures as well as of trends of lesion progression. Two trends of evolution could be discerned: one from normal to hyperplasia, atypical hyperplasia, and comedo DCIS as representative of high-grade lesions; and the other from normal to hyperplasia to cribriform DCIS, solid DCIS, and infiltrating cancer, representing lower grade lesions. The nuclei in microinfiltrating foci are distinctly different from nuclei in high-grade comedo DCIS. The nuclei in microinfiltrating foci have a statistically significantly lower nuclear abnormality. They may represent outgrowing clones.

Quantitative study of ductal breast cancer progression: nuclear signatures for evaluation of progression grade

The evaluation of progressive morphological changes, with 93 morphometric parameters in tissue lesions representative of ductal breast cancer progression, has been performed in order to define in great detail the profile of chromatin texture (nuclear signature) changes. A gradual, distinctive increase in nuclear signature alterations from hyperplasia to infiltrating carcinoma has been found. The nuclear signatures' analysis of microinfiltrating foci in comedo DCIS showed sharp differences compared with those of comedo DCIS they derived from: these foci consist of cells with smaller and also more homogeneous nuclei. Opposite to the prominent heterogeneity of those of comedo DCIS: they appear to express a reduced clonality in the new, more progressed, cell population. Digital analysis of chromatin patterns seems to be useful, beyond mere extraction of individual features of value, in getting objective data for individual grading and prognosis of breast cancer.

Relapse of low-grade gastric MALT lymphoma after Helicobacter pylori eradication: true relapse or persistence? Long-term post-treatment follow-up of a multicenter trial in the north-east of Italy and evaluation of the diagnostic protocol's adequacy

The effect of eradication of Helicobacter pylori on early stage gastric low-grade MALT lymphoma in 76 patients with follow-up of at least 1 year (12-63 months, mean 28) is reported. No regression was found in five cases after 12-48 months. In one case surgical resection detected the involvement of perigastric lymph nodes overlooked by endoscopic ultrasonography (EUS). Neither progression of the disease nor a high-grade component was documented by repeated gastric mappings, EUS and complete stagings in the other four cases. After histological remission five relapses of low-grade and one relapse of high-grade MALT lymphoma were found 12-48 months after eradication. Subsequent histological remission, without any additional therapy, was found in three relapsed cases. A rapid and persistent histological remission was obtained in 56 patients (73%). A late remission was observed in six cases. Monoclonal remission was found in half of the patients and was frequently delayed. Persistent monoclonality was associated with histological remission in the vast majority of patients. Our data confirm H. pylori eradication as the first choice therapy for early stage gastric low-grade MALT lymphoma and recommend extensive bioptic mapping and endoscopic sonography both in the local staging and in the regression evaluation. The rare cases of late remission encourage us to wait for at least 1 year after eradication of H. pylori. Longer follow-up studies will clarify the meaning of histological relapse/persistence and late remission. The study of non-responder cases could show us a step in lymphomagenesis.

Quantitative study of ductal breast cancer progression: signatures of nuclei in proliferating breast lesions and in situ cancer

AIMS

The objective of this study is to derive highly specific nuclear signatures (NS's) for the characterization of nuclei of ductal breast epithelium in proliferative lesions and in situ cancers in order to evaluate if nuclear structural changes are able to describe the main events of ductal cancer progression and if the method can be used for objective grading.

METHODS

A total of 82 different features descriptive of the nuclear chromatin patterns were computed in nuclei from normal glandular breast tissue, florid hyperplasia, and ductal carcinoma in situ (DCIS) and of DCIS with microinfiltration. The feature values were arranged to form a profile or signature. Measures of difference to a standard profile derived from normal glandular breast tissue were defined. One may then compute a standardized distance measure for a nucleus from "normal". Lesions can be characterized in the same manner, on the basis of the mean profile for all of their nuclei, and on the basis of the distribution of distances of their constituent nuclei from normal.

RESULTS

The selected histopathologic patterns on which the diagnostic categories for DCIS are based were found to have corresponding distinctive patterns in the chromatin of the lesion's nuclei. A monotonic trend of ductal neoplastic progression was found. In addition, lesions histologically assessed as belonging to the same diagnostic category were found to offer substantially different distribution patterns.

CONCLUSIONS

The full utilization of nuclear texture features allows the derivation of highly specific signatures for nuclei so that a reproducible grading can be performed for prognostic purposes.

Hypoplastic left heart syndrome with restrictive atrial septal defect and congenital pulmonary lymphangiectasis

The presence of a restrictive atrial septal defect in hypoplastic left heart syndrome represents a surgical emergency and may negatively affect survival after operation. A neonate with such a disease association, requiring septectomy upon birth developed intractable respiratory failure due to congenital pulmonary lymphangiectasis. The therapeutic implications of this rare pathologic condition are discussed.

Quantitative study of ductal breast cancer--patient targeted prognosis: an exploration of case base reasoning

Current analytic methodologies allow the extraction, even from small tumor masses, of extensive information on the biologic characteristics of malignant lesions, such as tumor aggressivity, metastatic potential, drug resistance, and host interactions. Clinical practice now offers a wide range of therapeutic strategies. Information technological advances offer the opportunity to refer to very large data bases of patient anamnestic data, response to treatment and clinical outcome. There is a need to formulate therapy and prognosis for each individual case. Case based reasoning is a knowledge based methodology where the outcome for complex situations can be predicted by referring to a large data base of cases of known outcomes. The preliminary data obtained from this study suggest that case based reasoning may offer a promising approach to individual targeted prognosis.

Renal cell carcinoma: Pathological prognostic criteria

– Pathological criteria so far employed in the prognosis of renal cell carcinoma provide no clinically useful information. This paper emphasises the possibilities offered by histopathology today for tackling this clinical problem more effectively. Nuclear analysis, with objective and quantitative evaluation of the degree of distortion, may provide extremely useful information. The authors correctly classified 90% of the 50 cases of renal cell carcinoma considered and whose follow-up at 5 years was known.

Quantitative study of ductal breast cancer progression. A progression index (P.I.) for premalignant lesions and in situ carcinoma

The diagnostic subjective assessment of ductal premalignant proliferative lesions and in situ carcinoma of the breast produces unsatisfactory results. Since the phenotypical cell changes in tumour progression toward infiltrating cancer constitute a continuum, a grading on a continuous scale of values produces a more reliable and reproducible characterization. The diagnostic assessment for any individual patient may be expressed by a progression index (P.I.): its numerical values are based on the cellular changes measured in the individual cases. In this study, the progression index is based on two morphometric features, nuclear size and nucleolar area. In addition, the method presented may produce a ratio, stating the relative likelihood that each case represents one of the conventional diagnostic categories. Such a likelihood ratio may be obtained from the bivariate distribution of nuclear size and nucleolar area for the conventional diagnostic categories.

Quantitative study of ductal breast cancer progression. Morphometric evaluation of phenotypical changes occurring in benign and preinvasive epithelial lesions

Fifty-nine cases of Breast Epithelial Proliferative Lesions (BEPL) and Ductal Carcinoma in Situ (DCIS), were studied by image analysis, to evaluate the nuclear changes occurring in the conventional diagnostic categories of ductal hyperplasia, atypical ductal hyperplasia and DCIS with quantitative methods. Diagnosis reproducibility is the main practical problem of these breast lesions. In fact, with subjective methods, the reproducibility appears to be very low and precarious especially for clinical demands. The objective, quantitative evaluation of cell phenotypical changes should be the method for both practical diagnostic problems and study of ductal cancer progression. The distribution pattern of the data in the feature, obtained with quantitative analysis, strongly suggests a continuum of changes, indicating an evolutionary process of Breast Ductal Carcinoma (BDC) progression in its preinvasive stage. Each observed case may be characterised by its own cellular, objective alterations and a progressive trend toward BDC can be stated. Since the actual changes of the proliferative phenotypes can be measured, and the values are reproducible, karyometric measurement may allow an objective grading of individual cases.

Breast solitary schwannoma: fine-needle aspiration biopsy and immunocytochemical analysis

A case of intramammary solitary schwannoma (SS) (benign neurilemoma) diagnosed by fine-needle aspiration biopsy (FNAB) and supported by immunocytochemical study is reported. The tumor arose in the right breast of an 18-yr-old woman and was clinically and radiologically considered a fibroadenoma. The smears obtained by FNAB of the lump showed clusters of spindle-shaped cells and suggested a benign mesenchymal neoplasm. The presence of some structures reminiscent of Verocay bodies and the immunocytochemical reactivity for S-100 protein antiserum demonstrated the schwannian nature of the tumor and suggested the diagnosis of SS. The final histologic examination confirmed the cytologic diagnosis.

Neoplastic epithelial cells in a subset of human thymomas express the B cell-associated CD20 antigen

A series of 36 human thymomas have been immunohistochemically analyzed using a panel of antibodies recognizing B-cell markers including CD20. Most thymomas exhibiting the cortical pattern, according to the criteria of Marino and Muller-Hermelink, were characterized by areas of medullary differentiation containing variable numbers of CD20+ B lymphocytes, thus mimicking the medulla of normal thymus. On the other hand, B cells were absent or rare in thymomas recognized as mixed using the same morphological criteria. Surprisingly, we observed in most mixed thymomas variable numbers of CD20+ spindle cells, characterized by long slender processes. Using double-marker analysis we could demonstrate the epithelial nature of these cells (expression of keratin and lack of lymphoid and B-cell-related markers). The immunoreactivity of thymoma epithelial cells with L26, an antibody widely used in the characterization of B-cell lymphomas, can represent a drawback of practical relevance in the differential diagnosis of mediastinal tumors.

Suppurative granulomatous lymphadenitis. Immunohistochemical evidence for a B-cell-associated granuloma

The cellular composition of suppurative granulomas was investigated by the application of monoclonal and polyclonal antibodies to paraffin sections and compared with nonsuppurative, hypersensitivity-type granulomas. Macrophages, T cells, and dendritic cells showed a similar distribution in both types of granulomas. In addition to the presence of granulocytes, a major difference between suppurative granulomas and hypersensitive-type granulomas concerned their relationship with B lymphocytes. Hypersensitive-type granulomas were surrounded by small mantle B cells, but they did not contain any B lymphocytes. In contrast, variable numbers of B cells were found either at the periphery or in the center of suppurative granulomas. In view of their morphology (medium size, pale cytoplasm, irregular nuclear shape) and phenotype (L26 +/LN1 -/MB2 +/MT2 +) these B lymphocytes closely resembled monocytoid B cells. The monocytoid B cells might have a role in the recruitment of polymorphonuclear granulocytes and in the development of the necrosis, which occur within suppurative granulomas.

Transbronchial biopsy in sarcoidosis: the role of immunohistochemical analysis for granuloma detection

In this study 27 transbronchial biopsy specimens obtained from patients with clinical and/or laboratory features suggestive for sarcoidosis were analysed with conventional morphology and immunohistochemistry comparing the sensitivity and reproducibility of the two methods. A limited panel of monoclonal antibodies recognizing epitopes resistant to conventional fixation and embedment procedures were used (CD45R0, CD68, anti-cheratin, anti-collagen IV). All specimens were independently observed by two different pathologists. On the basis of the recognition of bona-fide noncaseating granulomas, 9 cases were uniformly judged as positive, 10 cases as negative, but 8 cases were considered doubtful. Immunohistochemical analysis reliably demonstrated the presence of epithelioid cells in 3 of these cases and absence in 5. These data suggest that the use of a limited immunohistochemical analysis can significantly improve histological diagnosis of sarcoidosis on small transbronchial biopsies using conventional routine material.

Detection of calbindin-D immunoreactivity in human follicular dendritic cells

The calcium-binding protein calbindin-D (28 kD) has been analysed immunohistochemically in different human lymphoid tissues. Combined immunohistochemical staining showed that calbindin-D (28 kD) is expressed by only a proportion of dendritic cells within the light zone of germinal centres, where antigens in the form of immune complexes are trapped and presented to B lymphocytes. All other cell types including macrophages, interdigitating cells, and various lymphocyte populations were negative. The expression of calbindin-D in this functionally relevant subset of follicular dendritic cells could have a role in the regulation of proliferation and selection of memory B-cells by modulating the concentration of calcium ions. Calbindin-D may be a useful marker for analysing in situ the phases of follicular development in different physiological and pathological conditions.

Melanocyte-marker-HMB-45 is regularly expressed in angiomyolipoma of the kidney

HMB-45 (melanocytic cell-specific monoclonal antibody) immunoreactivity was investigated in 10 cases of angiomyolipoma (AML) (1 with massive regional lymph node involvement) of the kidney and detected in all of them. No HMB-45 immunoreactivity was found in other tumors of the region which can occasionally be confused with AML, such as renal cell carcinoma, Wilms' tumor, and retroperitoneal sarcoma (leiomyosarcoma and liposarcoma). These findings indicate that HMB-45 is not a melanocyte-restricted marker and suggest that its expression might be useful in distinguishing AML from other tumors of the kidney and retroperitoneum.

False-positive immunostaining of normal epithelia and carcinomas with ascites fluid preparations of antimelanoma monoclonal antibody HMB45

HMB45 is a melanoma-specific monoclonal antibody that has found widespread use in diagnostic pathology. Recent reports, however, have suggested that this antibody may cross-react with a small number of carcinomas and other epithelial cells. The authors tested the hypothesis that these latter reports represent examples of false-positive immunostaining by comparing the immunostaining on breast, salivary gland, and lung tumors with the following: (1) a commercial ascites preparation of this monoclonal antibody; (2) a protein A-purified antibody preparation derived from ascites fluid; and (3) supernatant fluid obtained from the hybridoma cell line. The authors found that all examples of nonmelanoma immunostaining in the carcinomas tested were eliminated with the nonascites fluid preparations, whereas strong immunostaining of melanomas was retained. The authors conclude that contaminated commercial ascites fluid preparations of HMB45 may account for most, if not all, of the reports of nonmelanoma immunostaining with HMB45.

Multimarker immunohistochemical staining of calgranulins, chloroacetate esterase, and S100 for simultaneous demonstration of inflammatory cells on paraffin sections

Mac387 monoclonal antibody (MAb) recognizes two calcium binding, myeloid-associated proteins, now termed calgranulins, expressed at high levels by neutrophils and monocytes. Calgranulins are related to migration inhibitory factor (MIF) and are lost in a few days from monocytes differentiated in vitro. This marker is therefore potentially useful to analyze macrophage heterogeneity and turnover in tissue sections. In this study, we developed an immunohistochemical multimarker technique, including calgranulin demonstration, suitable for analyzing different inflammatory cells on paraffin-embedded material. The technique was carried out in subsequent steps demonstrating (a) naphthol AS-D chloroacetate esterase (CAE); (b) S100 immunoreactivity using a rabbit antibody in peroxidase-antiperoxidase (PAP) staining; and (c) Mac387 immunoreactivity using the alkaline phosphatase-anti-alkaline phosphatase (APAAP) technique. CAE staining was introduced in this method to distinguish Mac387+/CAE- macrophages from Mac387+/CAE+ neutrophils, and Mac387-/CAE+ mast cells. S100 protein is strongly expressed within lymphoid tissues by dendritic accessory cells and was then applied to distinguish these cells from S100-macrophages. We have also verified the possibility of reducing the staining time for this time-consuming procedure by use of microwave irradiation. The technique was applied to a representative variety of normal and pathological samples to assess its usefulness for study of cell heterogeneity. Our results showed the multimarker technique to be highly informative in the study of inflammatory lesions (e.g., rheumatoid arthritis, sarcoid and cat-scratch granulomas, dermathopathic lymphadenopathy), and is of wide potential value as an aid to histopathological diagnosis of several diseases.

Peripheral giant cell granuloma: evidence for osteoclastic differentiation

Nine cases of peripheral giant cell granuloma of the oral cavity have been immunohistochemically analyzed to assess the nature of the giant cells. Giant cells were unreactive when tested with antibodies recognizing myelomonocytic and macrophage markers (lysozyme, MAC 387, HAM 56) but showed strong immunoreactivity with MB1, an antibody reactive with osteoclasts. It is concluded that giant cells characterizing giant cell granuloma exhibit a phenotype distinct from other giant cells found in sites of chronic inflammation and may be true osteoclasts.

Immunohistochemical differentiation of follicular lymphoma from florid reactive follicular hyperplasia with monoclonal antibodies reactive on paraffin sections

In this study monoclonal antibodies which recognize lymphoid-associated antigens on paraffin sections (LN1, MB2, L26, MT2, UCHL1) have been evaluated to assess their usefulness in the distinction between reactive and neoplastic lesions of lymphoid follicles. Thirty-three follicular lymphoma samples and 36 reactive samples (lymph nodes and tonsils) were analyzed. MT2 appeared as the most valuable immunophenotypic marker as emerged from a comprehensive quantitative evaluation of 2329 reactive follicles and 2288 neoplastic follicles performed on MT2 immunostained sections. MT2-positive follicles were found in all lymphoma samples but one. Overall 1908 of 2288 neoplastic follicles were judged as positive whereas no follicles with comparable strong MT2 immunoreactivity could be found in non neoplastic samples. These latter showed weak MT2 positivity only in about 10% (224/2329) of reactive follicles. This study confirms that MT2 follicular positivity can be considered a reliable marker of follicular neoplasia, although negative results ought to be considered with caution. The detection of centrofollicular cells outside the germinal centers, which is considered a reliable criterion of follicular neoplasia, was highly improved by LN1 immunostaining. On the other hand pan-B antibodies such as L26 and MB2 were less informative because of the large number of B-lymphocytes observed in interfollicular areas of nonneoplastic samples.

Breast carcinoma with positive results for melanoma marker (HMB-45). HMB-45 immunoreactivity in normal and neoplastic breast

HMB-45 (melanocytic cell-specific monoclonal antibody) immunoreactivity has been detected by the immunoperoxidase technique in the cytoplasm of 2 of 100 breast carcinomas. In addition, normal breast lobules and ducts were occasionally found to have positive results in 6 of 100 cases. These findings indicate the need to exercise caution in the interpretation of HMB-45 immunoreactivity for immunohistochemical characterization of neoplasms.