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Patients with acquired immunodeficiency syndrome (AIDS) are at increased risk of developing non Hodgkin's lymphomas (NHL). Current estimates indicate that 5-10% of HIV-infected individuals develop AIDS-related NHL (AIDS-NHL). AIDS-NHL share several clinical features, including frequent extranodal presentation, aggressive clinical course and poor outcome. However, AIDS-NHL are a heterogeneous group of malignancies. They traditionally included systemic and primary brain lymphomas, but nowadays their updated clinicopathologic spectrum also comprises two novel entities, namely primary effusion lymphoma and plasmablastic lymphoma of the oral cavity. In the last few years, several studies have shown that the pathologic heterogeneity of AIDS-NHL correlates with the heterogeneity of the molecular lesions associated with these lymphomas. However, despite their pathologic and molecular heterogeneity, AIDS-NHL have a common B-cell origin, although the precise stage of B-cell differentiation reflected by the different tumor types has not been clarified yet.

Six ovarian undifferentiated carcinomas (UCs) and 19 poorly differentiated serous (14 cases) and endometrioid (5 cases) carcinomas with areas of solid diffuse carcinomas have been considered for the study. Pathological findings were analyzed in conjunction with molecular analysis concerning the structure and expression of nm23-H1 gene. Differences in the frequency of loss of heterozigosity (LOH) of this gene have been observed between the two groups, UCs displaying lower percentage of LOH (1/5) as compared to poorly differentiated tumors (17/17). The remaining 3 cases (1 UC and 2 poorly differentiated carcinomas) were homozygotes, i.e., noninformative. UCs might occur as a consequence of cellular dedifferentiation, being at the end of the differentiation spectrum of epithelial ovarian tumors. Nevertheless, this study suggests that, in a fraction of cases, UCs could represent a distinct entity not involved in the malignant progression, associated with peculiar DNA anomalies, one possibly being that of the nm23-H1 deletion. In other words, a noticeable subset of UCs, not harboring nm23-H1 alterations, may be histologically uncommitted "ab initio". Moreover, nm23-H1 LOHs could be considered early events in the ovarian carcinogenesis, because similar molecular patterns were found both in primary and metastatic sites of the same tumor.

Cytogenetic analysis of Non-Hodgkin's Lymphomas (NHL) taken together with immunophenotypic and genotypic studies, may contribute to better define their morphologic classification. In this review the main cytogenetic data have been summarized, looking at a histopathologic NHL categorization that is related to a modern multiparametric approach. The correlation of non random chromosome abnormalities with NHL categories will augment information about their pathogenesis and tumor progression.