Gastric cancers of the microsatellite mutator phenotype display characteristic genetic and clinical features.

BACKGROUND & AIMS: Colon cancer of the microsatellite mutator phenotype (MMP) exhibits significant genotype differences from cancer without the MMP. Twenty-nine MMP-positive gastric cancers were analyzed to clarify if these genotype differences were also associated with distinctive clinicopathologic features. METHODS: Alterations of p53, beta2-microglobulin (beta2M ), hMLH1, and hMSH2 genes were analyzed by using polymerase chain reaction, single-strand conformational polymorphism, sequencing, microallelotyping, hypermethylation assays, and immunostaining. The results were contrasted with mutations in BAX, hMSH3, and hMSH6, genes target for the MMP. RESULTS: Tumors with the MMP had a significantly lower incidence of p53 gene mutations than the other tumors and often contained beta2M gene somatic mutations. Many tumors contained concomitant genetic and epigenetic alterations in DNA mismatch repair genes, hMLH1, hMSH2, hMSH3, and hMSH6. Gastric cancer of the MMP was associated with well/moderate differentiation, distal location, and better survival. CONCLUSIONS: Analysis of somatic alterations in microsatellite sequences and in cancer genes target for the MMP is useful for the classification of groups of gastric cancers with different prognosis. The results further support the concept that (gastric) cancer of the MMP represents a distinctive oncogenic pathway because the mutated cancer genes are usually different from those found in tumors without the MMP.

expression patterns of cyclins D1 and E in condyloma acuminatum in comparison with psoriatic proliferative lesions.

Human papillomavirus (HPV) is able to subvert the host cell replication machinery so as to foster viral reproduction. Specifically, HPV infection is known to induce expression of proliferation antigens such as Ki67 and proliferative cell nuclear antigen (PCNA) in differentiated keratinocytes which have ceased to replicate. In order to determine whether cyclin D1 or cyclin E deregulation is also a feature of HPV infection, an immunohistochemical investigation of cyclin D1, cyclin E, Ki67, and PCNA expression has been carried out in 38 cases of HPV 6/11-related condyloma acuminatum (CA). Results were compared with those obtained from 15 psoriatic proliferative lesions. Whereas 35 (92.1 per cent) CA samples exhibited positive nuclear immunostaining for cyclin E, no cyclin D1 immunoreaction was detected in any of the CA samples studied. All psoriatic lesions showed immunostaining for both cyclins. All CA cases revealed a positive immunoreaction for Ki67 and 33 for PCNA, both in the parabasal and in the differentiated upper epithelial layers. Parabasal keratinocytes of psoriatic lesions were always positive for both Ki67 and PCNA. These results indicate that in the onslaught of HPV 6/11 upon the keratinocyte replication machinery, cyclin E, PCNA, and Ki67 are amongst the targeted cell cycle modulators, whereas cyclin D1 is spared the main effects of virus-cell interplay. In contrast, both cyclins seem to be induced in psoriasis, a non-viral proliferative skin condition.

Cyclin D1 overexpression in non-small cell lung carcinoma: correlation with Ki67 labelling index and poor cytoplasmic differentiation.

Cyclin D1 is part of the molecular system regulating the cell cycle G1 to S transition point. Its overexpression, a common finding in carcinomas of the breast, oesophagus, and head and neck, has also been demonstrated in a high percentage of non-small cell lung carcinomas (NSCLCs). The role of cyclin D1 in NSCLC has been studied by correlating its immunoreactivity with the Ki67 labelling index in paraffin-embedded, autoclaved surgical samples of 56 NSCLC cases. In addition, flow cytometric determination of ploidy and cell cycle status was carried out on 172 fresh tumour samples from the same cases. Twenty-four (42.8 per cent) NSCLCs showed positive cyclin D1 immunostaining, a finding which showed no relationship to ploidy pattern, cell cycle phase, histological subtype, or lymph node metastasis, but was significantly associated with the Ki67 labelling index (P = 0.03) and with poor cytoplasmic differentiation (P = 0.01). Cyclin D1-positive nuclei were abundant in poorly differentiated zones and absent in the best differentiated areas, particularly in heavily keratinized fields. These data indicate that in NSCLC, cyclin D1 overexpression is not only associated with a high cell proliferation rate, but also seems to play a role in the process of tumour differentiation.

[Lymphoma of the marginal zone of the spleen. A case study]. / Linfoma de la zona marginal del bazo. Estudio de un caso.

Lymphomas of the marginal spleen zone are an entity recently considered as separate by the International Lymphoma Study Group. There are B-cell non Hodgkin's lymphomas (NHL) of low grade malignancy with a characteristic phenotype that allows to differentiate from mantle lymphomas and other B-cell lymphoproliferative syndromes. The case of a 69-year-old female patient admitted for abdominal pain due to large splenomegaly is reported. Pancytopenia and the presence of atypical large-sized lymphocytes with extensive cytoplasm and a rounded nucleus with indentations, reticulated appearing chromatin and one or several nucleoli were of note in the hemogram. Microscopic examination of the bone marrow demonstrated moderate-degree lymphocytary infiltration with grade I reticulin fibrosis. Laparotomy with splenectomy was performed. White pulp invasion with multifocal infiltration of the red pulp by lymphocytes of the same characteristics as those observed in the peripheral blood and bone marrow were observed on microscopic bone marrow examination. Immunophenotypic study of these lymphocytes was positive for CD19, CD20 and CD22 while being negative for CD5, CD10, CD23, CD25, CD11c and FMC7, the phenotype belonging to the lymphocytes of marginal spleen zone. Following splenectomy the patient recovered hemoperipheral counts and did not undergo additional treatment. The patient died due to septic shock of respiratory origin 4 months later. The clinical, morphologic and immunophenotypic features of marginal spleen zone lymphomas are reported with emphasis on the differences with other B-cell non Hodgkin's lymphomas of low malignancy.

Massive haemoptysis complicating prosthetic patch pulmonary embolism after atrial septal defect repair.

A case is presented of a 43 year old woman with massive haemotypsis secondary to non-thrombotic pulmonary embolism complicating atrial septal defect repair with a prosthetic patch. Non-thrombotic embolus must be considered in the differential diagnosis of massive haemoptysis.

p53 and proliferating cell nuclear antigen expression in JC virus-infected cells of progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML), a demyelinating disease of the central nervous system (CNS) caused by infection with JC papova virus (JCV), is characterized by marked atypical changes in the glial cells. The JCV T protein binds cellular p53 (a tumor suppressor gene product), which as a result loses its normal down regulating influence on the cell cycle. We hypothesized that this binding would stabilize p53 and prolong its half life, leading to its immunohistochemical detection. To prove our theory combined JCV DNA:DNA in situ hybridization (ISH) and glial fibrillary acidic protein (GFAP) immunohistochemistry (IHC) as well as p53/GFAP double IHC were performed on routinely processed sections of five brains obtained at autopsy and two cerebral biopsy specimens from seven patients with PML. All specimens showed JCV infected oligodendrocytes and bizarre looking astrocytes that immunostained strongly for p53. In addition, because loss of p53 function results in proliferating cell nuclear antigen (PCNA) overexpression PCNA/GFAP double IHC was carried out, and a positive immunoreaction was obtained in JCV infected cells in the two biopsy specimens. The evidence of p53 immunoreactivity in JCV harboring glial cells seems to indicate a link between the JCV induced stabilization/inactivation of p53 and the striking tumorlike glial changes seen in PML. Proliferating cell nuclear antigen overexpression in these cells further supports this pathogenetic construct.