The over diagnosis of diffuse mesothelioma: An analysis of 311 cases with recommendations for the avoidance of pitfalls

BACKGROUND

The diagnosis of mesothelioma may be challenging. We investigated a large database of cases in order to determine the frequency with which a diagnosis of mesothelioma was made incorrectly and the most frequent causes of error.

DESIGN

A database including more than 4000 consultation cases of histologically confirmed mesothelioma was examined to identify cases in which mesothelioma was diagnosed by at least one pathologist when the available information pointed towards a different diagnosis.

RESULTS

There were 311 cases misdiagnosed as mesothelioma. The most common category was metastatic carcinoma to the pleura or peritoneum (129 cases: 73 lung carcinomas, 15 renal cell carcinomas). The next most common category was primary lung cancer (111 cases: 55 sarcomatoid carcinoma, 56 pseudomesotheliomatous carcinoma). The third most common category was primary malignancies arising from or near the serosal membranes (33 cases). The fourth most common category was fibrous pleurisy (38 cases). The most common errors were failure to consider important radiographic information regarding the gross distribution of tumor, lack of awareness or consideration of another malignancy, overreliance on certain immunohistochemical results, and failure to perform certain diagnostic histochemical, immunohistochemical, or ultrastructural studies.

CONCLUSIONS

There are a number of diagnostic pitfalls that can lead to the over diagnosis of mesothelioma. Careful attention to clinical and radiographic information as well as performance of appropriate ancillary tests can help to prevent such misdiagnoses. Detailed examples will be presented to assist in the avoidance of these pitfalls with emphasis on the most commonly observed errors.

Anti-glioblastoma activity of monensin and its analogs in an organoid model of cancer

Glioblastoma (GBM) remains the most frequently diagnosed primary malignant brain cancer in adults. Despite recent progress in understanding the biology of GBM, the clinical outcome for patients remains poor, with a median survival of approximately one year after diagnosis. One factor contributing to failure in clinical trials is the fact that traditional models used in GBM drug discovery poorly recapitulate patient tumors. Previous studies have shown that monensin (MON) analogs, namely esters and amides on C-26 were potent towards various types of cancer cell lines. In the present study we have investigated the activity of these molecules in GBM organoids, as well as in a host:tumor organoid model. Using a mini-ring cell viability assay we have identified seven analogs (IC₅₀ = 91.5 ± 54.4–291.7 ± 68.8 nM) more potent than parent MON (IC₅₀ = 612.6 ± 184.4 nM). Five of these compounds induced substantial DNA fragmentation in GBM organoids, suggestive of apoptotic cell death. The most active analog, compound 1, significantly reduced GBM cell migration, induced PARP degradation, diminished phosphorylation of STAT3, Akt and GSK3β, increased ɣH2AX signaling and upregulated expression of the autophagy associated marker LC3-II. To investigate the activity of MON and compound 1 in a tumor microenvironment, we developed human cerebral organoids (COs) from human induced pluripotent stem cells (iPSCs). The COs showed features of early developing brain such as multiple neural rosettes with a proliferative zone of neural stem cells (Nestin+), neurons (TUJ1 +), primitive ventricular system (SOX2 +/Ki67 +), intermediate zone (TBR2 +) and cortical plate (MAP2 +). In order to generate host:tumor organoids, we co-cultured RFP-labeled U87MG cells with fully formed COs. Compound 1 and MON reduced U87MG tumor size in the COs after four days of treatment and induced a significant reduction of PARP expression. These findings highlight the therapeutic potential of MON analogs towards GBM and support the application of organoid models in anti-cancer drug discovery.

Fluorescent Immunohistochemistry

Immunofluorescence is an important immunochemical technique that utilizes fluorescence-labeled antibodies to detect specific target antigens. It is used widely in both scientific research and clinical laboratories. Immunofluorescence allows for excellent sensitivity and amplification of signal in comparison to immunohistochemistry. However, analysis of samples labeled with fluorescence-labeled antibodies has to be performed using a fluorescence microscope or other type of fluorescence imaging. There are two methods available: direct (primary) and indirect (secondary) immunofluorescence. Here, we describe the principle of immunofluorescence methods as well as the preparation of fresh-frozen and formalin-fixed, paraffin embedded tissues for both direct and indirect immunofluorescence labeling.

Limitations of an ex vivo breast cancer model for studying the mechanism of action of the anticancer drug paclitaxel

Paclitaxel is widely used in the treatment of breast, ovarian, lung, and other cancers. Its primary mechanism is to prevent microtubule depolymerization causing loss of dynamic instability crucial for normal microtubule function leading to mitotic arrest. Prolonged mitotic arrest results in cell death as a secondary response. The effects of paclitaxel are typically studied in cell lines which precludes assessment of the possible influence of tumor-associated cells. We therefore examined paclitaxel action ex vivo in fresh explant cultures of human breast tumors. Surprisingly, we found that paclitaxel failed to induce tumor cell death in explant culture, in contrast to several other cytotoxic agents including salinomycin and vincristine. The lack of effect was not due to defective drug uptake, and furthermore, analysis of H&E stained tumor slices indicated that paclitaxel treatment caused defective (granular) mitosis and chromosomal condensation in 5-10% of tumor cells after 72 h. These results suggest that while paclitaxel was able to penetrate into the tumor slice and disrupt mitosis in cycling tumor cells, any ensuing cell death likely occurred beyond the useful lifetime of the tumor slices. We conclude that explant culture systems may be inappropriate for the study of cytotoxic drugs where a delay exists between the drug's primary and secondary modes of action.

Carbamate derivatives of colchicine show potent activity towards primary acute lymphoblastic leukemia and primary breast cancer cells-in vitro and ex vivo study

Colchicine (COL) shows strong anticancer activity but due to its toxicity towards normal cells its wider application is limited. To address this issue, a library of 17 novel COL derivatives, namely N-carbamates of N-deacetyl-4-(bromo/chloro/iodo)thiocolchicine, has been tested against two types of primary cancer cells. These included acute lymphoblastic leukemia (ALL) and human breast cancer (BC) derived from two different tumor subtypes, ER+ invasive ductal carcinoma grade III (IDCG3) and metastatic carcinoma (MC). Four novel COL derivatives showed higher anti-proliferative activity than COL (IC₅₀  = 8.6 nM) towards primary ALL cells in cell viability assays (IC₅₀ range of 1.1-6.4 nM), and several were more potent towards primary IDCG3 (IC₅₀ range of 0.1 to 10.3 nM) or MC (IC₅₀ range of 2.3-9.1 nM) compared to COL (IC₅₀ of 11.1 and 11.7 nM, respectively). In addition, several derivatives were selectively active toward primary breast cancer cells compared to normal breast epithelial cells. The most promising derivatives were subsequently tested against the NCI panel of 60 human cancer cell lines and seven derivatives were more potent than COL against leukemia, non-small-cell lung, colon, CNS and prostate cancers. Finally, COL and two of the most active derivatives were shown to be effective in killing BC cells when tested ex vivo using fresh human breast tumor explants. The present findings indicate that the select COL derivatives constitute promising lead compounds targeting specific types of cancer.

Synthesis and Anticancer Activity of Tertiary Amides of Salinomycin and Their C20-oxo Analogues

The polyether ionophore salinomycin (SAL) has captured much interest because of its potent activity against cancer cells and cancer stem cells. Our previous studies have indicated that C1/C20 double-modification of SAL is a useful strategy to generate diverse agents with promising biological activity profiles. Thus, herein we describe the synthesis of a new class of SAL analogues that combine key modifications at the C1 and C20 positions. The activity of the obtained SAL derivatives was evaluated using primary acute lymphoblastic leukemia, human breast adenocarcinoma and normal mammary epithelial cells. One single- [N,N-dipropyl amide of salinomycin (5 a)] and two novel double-modified analogues [N,N-dipropyl amide of C20-oxosalinomycin (5 b) and piperazine amide of C20-oxosalinomycin (13 b)] were found to be more potent toward the MDA-MB-231 cell line than SAL or its C20-oxo analogue 2. When select analogues were tested against the NCI-60 human tumor cell line panel, 4 a [N,N-diethyl amide of salinomycin] showed particular activity toward the ovarian cancer cell line SK-OV-3. Additionally, both SAL and 2 were found to be potent ex vivo against human ER/PR⁺ , Her2^- invasive mammary carcinoma, with 2 showing minimal toxicity toward normal epithelial cells. The present findings highlight the therapeutic potential of SAL derivatives for select targeting of different cancer types.

The response of phyllodes tumor of the breast to anticancer therapy: An in vitro and ex vivo study

Phyllodes tumors of the breast (PTB) are uncommon stromal-epithelial neoplasms, with the main recommended treatment being surgical removal. However, even with adequate resection, the risk of recurrence in the malignant form remains as high as 40%, and there is no recognized consensus on the most effective drugs for PTB. In the present study, an ex vivo model of malignant phyllodes and derived primary cell cultures were used to evaluate the effectiveness of a panel of different drugs, including the Bcl-2/Bcl-xL inhibitor ABT-263, salinomycin (SAL), doxorubicin (DOX), paclitaxel (TAX), vincristine (VCR), colchicine (COL) and cisplatin (CIS). ABT-263, SAL and DOX were highly effective towards phyllodes spindle cells when assessed in the ex vivo model, contributing to ~98% tumor cell death. Furthermore, ABT-263 was highly selective for tumor cells in this system, and exhibited little toxic effect on adjacent normal epithelial cells. Furthermore, consistent with findings in the ex vivo model, ABT-263 was significantly less toxic towards MCF 10A non-tumorigenic breast epithelial cells compared with SAL and DOX. A conditional reprogramming strategy was subsequently used, involving Rho kinase inhibition, to successfully generate primary phyllodes tumor cells that could be cultured for several passages. The primary cells were sensitive to DOX with an IC₅₀ of 0.40±0.07 µM in a standard viability assay and the preliminary results were obtained indicating sensitivity to ABT-263 and SAL. The present study demonstrated the feasibility of using explants and primary cells for drug discovery, selectively targeting PTB cells.

Human Polyomavirus JCPyV and Its Role in Progressive Multifocal Leukoencephalopathy and Oncogenesis

The human neurotropic virus JCPyV, a member of the Polyomaviridiae family, is the opportunistic infectious agent of Progressive Multifocal Leukoencephalopathy (PML), a fatal disease seen in severe immunosuppressive conditions and, during the last decade, in patients undergoing immunotherapy. JCPyV is a ubiquitous pathogen with up to 85% of the adult population word-wide exhibiting antibodies against it. Early experiments demonstrated that direct inoculation of JCPyV into the brain of different species resulted in the development of brain tumors and other neuroectodermal-derived neoplasias. Later, several reports showed the detection of viral sequences in medulloblastomas and glial tumors, as well as expression of the viral protein T-Antigen. Few oncogenic viruses, however, have caused so much controversy regarding their role in the pathogenesis of brain tumors, but the discovery of new Polyomaviruses that cause Merkel cell carcinomas in humans and brain tumors in racoons, in addition to the role of JCPyV in colon cancer and multiple mechanistic studies have shed much needed light on the role of JCPyV in cancer. The pathways affected by the viral protein T-Antigen include cell cycle regulators, like p53 and pRb, and transcription factors that activate pro-proliferative genes, like c-Myc. In addition, infection with JCPyV causes chromosomal damage and T-Antigen inhibits homologous recombination, and activates anti-apoptotic proteins, such as Survivin. Here we review the different aspects of the biology and physiopathology of JCPyV.

Human Colors-The Rainbow Garden of Pathology: What Gives Normal and Pathologic Tissues Their Color?

CONTEXT

- Colors are important to all living organisms because they are crucial for camouflage and protection, metabolism, sexual behavior, and communication. Human organs obviously have color, but the underlying biologic processes that dictate the specific colors of organs and tissues are not completely understood. A literature search on the determinants of color in human organs yielded scant information.

OBJECTIVES

- To address 2 specific questions: (1) why do human organs have color, and (2) what gives normal and pathologic tissues their distinctive colors?

DATA SOURCES

- Endogenous colors are the result of complex biochemical reactions that produce biologic pigments: red-brown cytochromes and porphyrins (blood, liver, spleen, kidneys, striated muscle), brown-black melanins (skin, appendages, brain nuclei), dark-brown lipochromes (aging organs), and colors that result from tissue structure (tendons, aponeurosis, muscles). Yellow-orange carotenes that deposit in lipid-rich tissues are only produced by plants and are acquired from the diet. However, there is lack of information about the cause of color in other organs, such as the gray and white matter, neuroendocrine organs, and white tissues (epithelia, soft tissues). Neoplastic tissues usually retain the color of their nonneoplastic counterpart.

CONCLUSIONS

- Most available information on the function of pigments comes from studies in plants, microorganisms, cephalopods, and vertebrates, not humans. Biologic pigments have antioxidant and cytoprotective properties and should be considered as potential future therapies for disease and cancer. We discuss the bioproducts that may be responsible for organ coloration and invite pathologists and pathology residents to look at a "routine grossing day" with a different perspective.

Flat pattern of nephrogenic adenoma: previously unrecognized pattern unveiled using PAX2 and PAX8 immunohistochemistry

Nephrogenic adenoma is a benign lesion of the urinary tract, particularly the urinary bladder. It is a gross and microscopic mimicker of urothelial neoplasm or metastatic carcinoma. Several histological patterns (tubular, tubulocystic, polypoid, papillary, fibromyxoid) have been recognized, but a flat pattern has not been described. Histologically, nephrogenic adenoma consists of tubules, cysts or papillae lined by flat to polygonal cells with frequent hobnail appearance. The stroma is often edematous or has a granulation tissue-like appearance with acute or chronic inflammation. By immunohistochemistry, nephrogenic adenomas are positive for renal epithelial markers CK7, CD10 and alpha-methylacyl-coenzyme A racemase, and negative for bladder urothelium or prostate markers. Recent studies have shown that nephrogenic adenomas are positive for PAX2 and PAX8. We encountered an interesting case of tubular nephrogenic adenoma with adjacent areas suspicious of flat urothelial atypia. Immunohistochemistry for PAX2 and PAX8 were positive in these areas, unveiling a flat pattern of nephrogenic adenoma. This case prompted us to study 15 cases of nephrogenic adenoma to determine additional instances of flat pattern and to assess the value of PAX2 and PAX8 immunoreactivity to diagnose nephrogenic adenoma. PAX2 and PAX8 immunostaining was positive in 14/15 and 15/15 cases, respectively. The flat pattern was present at least focally adjacent to tubular, polypoid and papillary areas, in 8/15 cases of nephrogenic adenoma. In conclusion, the flat pattern is a common finding in nephrogenic adenomas, but easily under recognized by morphologic examination and may be confused with flat urothelial lesions with atypia. Immunostains for PAX2 and PAX8 are useful in the detection of nephrogenic adenomas and particularly unveil those nephrogenic adenomas with flat pattern.

Follicular adenoma with extensive extracellular mucin deposition: report on two cases

We report two cases of follicular adenoma of the thyroid with extensive extracellular mucin deposition. Fine needle aspiration in Case 1 showed singly discohesive polygonal cells in a granular mucinous background. They contained abundant eosinophilic cytoplasm, nuclear irregularities, and frequent nuclear inclusions with occasional bizarre mitoses. A right lobectomy was done. In Case 2, a 47-year-old Caucasian woman with multinodular goiter had total thyroidectomy and a yellow-tan nodule was found within the right lobe. Both tumors were well-encapsulated masses with thick capsules. Each was characterized by microfollicles without papillae in a mucinous stroma. Tumor cells were positive for thyroglobulin and negative for calcitonin, CEA, galectin-3, HBME-1, and CK19. The extracellular mucin stained with Alcian-blue and colloidal iron but not with mucicarmine and D-PAS. No BRAF gene mutation was detected. Because there were neither capsular nor vascular invasions, both cases were diagnosed as follicular adenomas of the thyroid with extensive extracellular mucin deposition, which as proposed by the WHO classification can be categorized as a mucinous variant of follicular adenoma. Retrospectively, frequent nuclear inclusions and the absence of nuclear grooves in the mucin-containing background of cytologic smears and histologic sections were shared by those of mucin-producing papillary carcinoma. It is unclear whether it belongs to an existing category of thyroid neoplasm with mucin production or whether it is truly a new tumor variant. Furthermore, pathologists should pay attention to avoid misdiagnosis of this variant of follicular neoplasm that shows an overlapping cytology with that of papillary carcinoma.

Synchronous clear cell renal cell carcinoma and tubulocystic carcinoma: genetic evidence of independent ontogenesis and implications of chromosomal imbalances in tumor progression

Seven percent of renal cell carcinoma (RCC) cases are diagnosed as "unclassified" RCC by morphology. Genetic profiling of RCCs helps define renal tumor subtypes, especially in cases where morphologic diagnosis is inconclusive. This report describes a patient with synchronous clear cell RCC (ccRCC) and a tubulocystic renal carcinoma (TCRC) in the same kidney, and discusses the pathologic features and genetic profile of both tumors. A 67 year-old male underwent CT scans for an unrelated medical event. Two incidental renal lesions were found and ultimately removed by radical nephrectomy. The smaller lesion had multiple small cystic spaces lined by hobnail cells with high nuclear grade separated by fibrous stroma. This morphology and the expression of proximal (CD10, AMACR) and distal tubule cell (CK19) markers by immunohistochemistry supported the diagnosis of TCRC. The larger lesion was a typical ccRCC, with Fuhrman's nuclear grade 3 and confined to the kidney. Molecular characterization of both neoplasms using virtual karyotyping was performed to assess relatedness of these tumors. Low grade areas (Fuhrman grade 2) of the ccRCC showed loss of 3p and gains in chromosomes 5 and 7, whereas oncocytic areas displayed additional gain of 2p and loss of 10q; the high grade areas (Fuhrman grade 3) showed several additional imbalances. In contrast, the TCRC demonstrated a distinct profile with gains of chromosomes 8 and 17 and loss of 9. In conclusion, ccRCC and TCRC show distinct genomic copy number profiles and chromosomal imbalances in TCRC might be implicated in the pathogenesis of this tumor. Second, the presence of a ccRCC with varying degrees of differentiation exemplifies the sequence of chromosomal imbalances acquired during tumor progression.

CCL8/MCP-2 is a target for mir-146a in HIV-1-infected human microglial cells

MicroRNA-mediated regulation of gene expression appears to be involved in a variety of cellular processes, including development, differentiation, proliferation, and apoptosis. Mir-146a is thought to be involved in the regulation of the innate immune response, and its expression is increased in tissues associated with chronic inflammation. Among the predicted gene targets for mir-146a, the chemokine CCL8/MCP-2 is a ligand for the CCR5 chemokine receptor and a potent inhibitor of CD4/CCR5-mediated HIV-1 entry and replication. In the present study, we have analyzed changes in the expression of mir-146a in primary human fetal microglial cells upon infection with HIV-1 and found increased expression of mir-146a. We further show that CCL8/MCP-2 is a target for mir-146a in HIV-1 infected microglia, as overexpression of mir-146a prevented HIV-induced secretion of MCP-2 chemokine. The clinical relevance of our findings was evaluated in HIV-encephalitis (HIVE) brain samples in which decreased levels of MCP-2 and increased levels of mir-146a were observed, suggesting a role for mir-146a in the maintenance of HIV-mediated chronic inflammation of the brain.

Bone marrow-derived mesenchymal stem cells undergo JCV T-antigen mediated transformation and generate tumors with neuroectodermal characteristics

There is now accumulating evidence showing that some tumors may arise from transformed stem cells. In this study we demonstrate that adult bone marrow- derived mesenchymal stem cells (MSCs) undergo neoplastic transformation induced by the human polyomavirus JCV, early protein, T-antigen, and are tumorigenic when transplanted into the flanks of Nude mice as compared to non-transformed MSCs. Histologically, the tumors are heterogeneous with mesenchymal and neural crest characteristics as evidenced by expression of the neural crest markers p75, SOX-10, and S-100, with populations of tumor cells exhibiting characteristics of primitive neuroectodermal cells. In addition, a subset of T-antigen positive tumor cells exhibit a high proliferation index as detected by Ki-67 labeling, and co-express CD133, a marker which is expressed on cancer stem cells. These results show that tumors with neuroectodermal characteristics may arise from transformation of MSCs, a globally accessible adult stem cell with multipotent differentiation capacity. In light of earlier reports on the association of JCV with a broad variety of human tumors, our data suggests that T-antigen transformation of adult stem cells with a multipotent capacity can serve as a possible common origin for some of these cancers, and offers a novel model for oncogenesis.

Leptin and its receptor are overexpressed in brain tumors and correlate with the degree of malignancy

Although leptin and its receptor (ObR) have emerged as important cancer biomarkers, the role of the leptin system in brain tumor development remains unknown. We screened 87 human brain tumor biopsies using immunohistochemistry and detected leptin and ObR in 55.2% and 60.9% cases, respectively. In contrast, leptin and ObR were absent in 14 samples of normal brain tissue. The presence of leptin correlated with ObR with overall concordance 80.5%. The leptin/ObR system was highly expressed in glioblastomas and anaplastic astrocytomas, while lower expression of both markers was noted in low-grade astrocytomas and gangliogliomas. The association between leptin/ObR and the degree of tumor malignancy was highly significant (P < 0.001). Using double immunofluorescence of glioblastoma tissues, we found co-expression of leptin with ObR and with the proliferation marker Ki-67 in 87% and 64% of cells, respectively. The leptin/ObR-positive tissues also expressed activated forms of STAT3 and Akt. In line with this finding, ObR-positive glioblastoma cells responded to leptin with cell growth and induction of the STAT3 and Akt pathways as well as inactivation of the cell cycle suppressor Rb. In summary, our data demonstrate that the leptin/ObR system is expressed in malignant brain tumors and might be involved in tumor progression.

Hypoxia inducible factor-1 alpha activation of the JCV promoter: role in the pathogenesis of progressive multifocal leukoencephalopathy

Activation of viral promoter transcription is a crucial event in the life cycle of several viruses. Hypoxia inducible factor-1 alpha (HIF-1alpha) is an inducible transcription factor whose activity is dependent on environmental conditions, most notably oxygen levels and cellular stress. HIF-1alpha has been implicated in the pathogenesis of several viruses, including HIV-1, HHV-8 and RSV. Under hypoxic conditions or oxidative stress, HIF-1alpha becomes stable and translocates to the nucleus, where it modulates gene transcription. The objective of the present study was to investigate a possible role for HIF-1alpha in the activation of JCV. Glial cell cultures infected with JCV demonstrated a significant increase in the levels of HIF-1alpha, in where it is located to the nucleus. Immunohistochemical studies corroborated upregulation of HIF-1alpha in JCV infected oligodendrocytes and astrocytes in clinical samples of PML compared with normal glial cells from the same samples in which HIF-1alpha expression is weak. CAT assays performed in co-transfected glial cells demonstrated activation of the JCV early promoter in the presence of HIF-1alpha. This activation was potentiated in the presence of Smad3 and Smad4. Finally, chromatin immunoprecipitation assays demonstrated the binding of HIF-1alpha to the JCV control region. These results suggest a role for HIF-1alpha in the activation of JCV; understanding of this pathway may lead to the development of more effective therapies for PML, thus far an incurable disease.

Immunohistochemical characterization of Renaut bodies in superficial digital nerves: further evidence supporting their perineurial cell origin

Renaut bodies are well-demarcated cylindrical (circular in cross section) hyaline structures attached to the inner layer of the perineurium that can be found in normal and pathological nerves of various animals and humans. They are composed of spidery fibroblasts and perineurial cells immersed in an extracellular matrix that contains randomly oriented collagen fibers and elastin precursors but not axons or Schwann cells. Frequently, they are associated with thickened subperineurial capillaries. As Renaut bodies are mainly located at sites of nerve compression, it is hypothesized they may act as 'protective cushions' for endoneurial components, and that they may be formed as a secondary reaction to trauma. Herein, we report the presence of Renaut bodies within numerous small dermal nerve trunks in an amputated finger. By immunohistochemistry, Renaut bodies expressed markers identical to those of perineurial cells (epithelial membrane antigen, Glut-1, and claudin-1), supporting the concept of a closely associated perineurial but not endoneurial origin. In addition, expression of hypoxia-inducible factor 1 alpha (which has been shown to increase Glut-1 transcription), neurofibromatosis 1 gene related product and NF-2, were also detected in these peripheral nerve structures.

CD4+/CD56+ hematodermic neoplasm: presentation of 2 cases and review of the concept of an uncommon tumor originated in plasmacytoid dendritic cells expressing CD123 (IL-3 receptor alpha)

CD4/CD56 hematodermic neoplasm is a rare neoplasm presenting with cutaneous nodules, lymphadenopathy, bone marrow infiltration, and an aggressive clinical course. Recently, the plasmacytoid dendritic cell origin of this neoplasm has been demonstrated. Plasmacytoid dendritic cell is a hematopoietic-derived cell implicated in the regulation of innate and adaptive cell immunity and in the production of certain regulatory cytokines. Recently it has been demonstrated that these cells express cell surface markers such as IL-3 receptor alpha (CD123). In the present report, we describe the clinical, histologic, and immunohistochemical characteristics of 2 cases of CD4/CD56 hematodermic neoplasm. Both patients were male and the age at the time of diagnosis was 36 and 75 years, respectively. Clinical findings were limited to the skin and consisted of multiple cutaneous nodules located in the thorax and extremities, some of them ulcerated. Histologically, the tumors were characterized by a nonepidermotropic, dermal and subdermal infiltration of homogeneous medium-sized cells resembling lymphoblasts or myeloblasts. Immunohistochemical characterization of the tumors showed expression of CD4, CD56, CD43, and CD123, whereas CD8, CD20, and MPO were negative. Immunoreactivity for CD3, which has been described in rare occasions, was found only in one of the cases. This characteristic profile in addition to the expression of CD123, which was detected in both cases, can be used as valuable tools in the diagnosis of this rare neoplasm.

[Diagnosis of early gastric marginal zone lymphoma (MALT lymphoma) in endoscopic biopsies. Report of a case that demonstrates the utility of immunohistochemistry and the molecular analysis.]

MALT lymphomas are a subtype of low grade lymphomas that represent 7-8% of all B-cell lymphomas originated in extranodal sites. Nearly 50% of the cases present as primary gastric lymphomas.They arise from the acquired MALT developed during the course of H. pylori chronic infection. Microscopically,the presence of lymphoid follicles with follicular colonization, marginal zone ("centrocytoid")cells and lymphoepithelial lesions is characteristic.Histopathological diagnosis may result difficult in superficial endoscopic biopsies showing a typical lymphoid infiltrates. Using Wotherspoon criteria along with molecular analyses is useful in borderline lesions. We present the case of a 62 years old female with chronic gastritis. A small endoscopic biopsy was performed and the presence of a heterogeneous lymphoid infiltrate in the lamina propia was observed. Immuno histochemical profile showed focal co expression of CD20 andCD43 and kappa light chain restriction. The diagnosis of an atypical lymphoid infiltrate highly suspicious of MALT lymphoma was established. PCR molecular analysis corroborated the monoclonal pattern of the lymphoid cells and the diagnosis of lymphoma. Immunohistochemical and molecular analyses in cases of lymphoid infiltrates suspicious of malignancy (Wotherspoon 3 and 4) will aid in the adequate diagnosis between chronic gastritis and MALT lymphoma, which is crucial for prognosis,treatment and patient's outcome.Key words: Chronic reactive gastritis, marginal zone lymphoma, MALT lymphoma, gastriclym.

Effects of JC virus infection on anti-apoptotic protein survivin in progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease of the central nervous system resulting from the productive infection of oligodendrocytes by the opportunistic polyomavirus JC virus (JCV). Apoptosis is a host defense mechanism to dispose of damaged cells; however, certain viruses have the ability to deregulate apoptotic pathways to complete their life cycles. One such pathway involves survivin, a member of the inhibitor of apoptosis family, which is abundantly expressed during development in proliferating tissues but should be absent in normal, terminally differentiated cells. Immunohistochemistry performed in 20 cases of PML revealed the presence of survivin in JCV-infected oligodendrocytes and bizarre astrocytes within demyelinated plaques. Survivin up-regulation was also found in oligodendroglial and astrocytic cultures infected with JCV. Cell cycle analysis and DNA laddering demonstrated a significantly lower number of cells undergoing apoptosis on JCV infection compared with noninfected cultures; small interfering RNA inhibition of survivin resulted in a dramatic increase in apoptotic cells in JCV-infected cultures. This is the first report describing the activation of survivin by JCV infection in vitro and in PML clinical cases. These observations provide new insights into the anti-apoptotic mechanisms used by JCV to complete its lytic cycle and may suggest new therapeutic targets for PML.

[Historical development and current concepts on B-cell lymphomas of the marginal extraganglionar site of lymphoid tissue associated with MALT lymphoma. A tribute to Dennis H Wright and Peter G Isaacson]

Significant advances in the understanding of marginal zone lymphoma since the first description in 1983 by Peter Isaacson and Dennis Wright have been noted. MALT lymphomas are a subgroup of low-grade B-cell lymphomas that arise from extranodal sites, comprising 7-8% of all B-cell lymphomas and displaying distinct clinicopathological characteristics. MALT lymphomas remain localized in the primary site for long periods of time and seldom disseminate unto other organs. These type of lymphomas infrequently arise in native MALT, but instead arise in MALT acquired in the course of chronic inflammatory disorders, such as Sjögren's syndrome and Helicobacter pylori infection. Eradication of H. pylori produces a clinical regression of the lymphoma in about 75% of cases. The histological hallmarks of MALT lymphoma include neoplastic centrocyte-like B cells, cells resembling monocytoid cells and the presence of lymphoepithelial lesions. The gastrointestinal tract, particularly the stomach, include two-thirds of cases; however MALT lymphomas also occur in other organs such as salivary glands, lung, thyroid, ocular adnexa, breast and skin. Genetic studies have identified three chromosomal translocations specifically associated with MALT lymphomas that include: t(1l:18)(q21;q21), t(1;14)(p22;q32), and t(14;18)(q32;q21). Although these translocations involve different genes, they appear to share a common oncogenic pathway involving NFkappaB.

Glioblastoma multiforme with small cell neuronal-like component: association with human neurotropic JC virus

The human polyomavirus JCV, the etiological agent of progressive multifocal leukoencephalopathy, has been associated with primitive neuroectodermal tumors and various glial-derived tumors, including glioblastoma multiforme (GBM). Here we describe the unique clinical case of a 54-year-old man who presented with headaches, hemiparesis and drowsiness. T1 and T2 magnetic resonance images revealed a large solid tumor with a cystic component located in the right temporal lobe, with extension into the parietal lobe. Histologically, the tumor was composed of two areas, a main area of large neoplastic cells with pleomorphic atypical nuclei and abundant cytoplasm, which by immunohistochemistry was reactive for glial fibrillary acidic protein, mixed with several foci of poorly differentiated tumoral cells with elongated nuclei and scant cytoplasm, negative for GFAP, but robustly immunoreactive for synaptophysin and phosphoneurofilaments. Results from PCR in laser capture microdissected cells from both areas of the tumor revealed the presence of DNA sequences corresponding to the early, late and control regions (CR) of the JCV genome and expression of JCV proteins T-antigen and Agnoprotein in both phenotypes. No evidence for capsid protein was observed, excluding productive viral infection. Sequencing demonstrated the presence of the JCV Mad-1 strain with distinct point mutations in the CR of isolates from both, GBM and small cell architectural areas. The presence of JCV DNA sequences and expression of viral proteins further reinforces the role of the widely spread human neurotropic virus in early transformation and in the development of brain tumors.

HIV disorders of the brain: pathology and pathogenesis

Infection with HIV-1 has spread exponentially in recent years to reach alarming proportions. It is estimated than more than 33 million adults and 1.3 million children are infected worldwide. Approximately 16,000 new cases are diagnosed every day and almost 3 million people die every year from AIDS, making it the fourth leading cause of death in the world. Since the introduction of highly active anti-retroviral therapy (HAART) in the mid 1990s, the morbidity and mortality associated with HIV-1 infection has significantly decreased and AIDS has become a chronic disorder. However, neuropathological conditions associated with AIDS are still present in approximately 70 to 90% of patients and can be the result of HIV itself or of opportunistic infections. Here we briefly review the pathology and pathophysiology of AIDS-Encephalopathy, of some of the significant opportunistic infections affecting the brain in the context of AIDS, including Progressive Multifocal Leukoencephalopathy (PML) a demyelinating disease caused by the human neurotropic JC virus, Toxoplasmosis, Cryptococcosis and of primary CNS lymphoma, a brain malignancy frequently associated with HIV-1 infection, all of them considered AIDS defining conditions.