Chiara Minacci

Origin of Microsatellite Instability in Gastric Cancer

Microsatellite instability (MSI) is observed in 13-44% of gastric carcinoma. The etiology of MSI in gastric carcinoma has not been clearly defined. To assess the role of mismatch repair in the development of MSI in gastric cancer, expression of hMSH2 and hMLH1 was explored. We examined 117 gastric carcinomas for MSI and observed instability at one or more loci in 19 (16%) of these tumors. Of the 19 tumors with MSI, nine exhibited low-rate MSI (MSI-L) with instability at <17% of loci, whereas the remaining 10 exhibited high-rate MSI (MSI-H) with instability at >33% of loci examined. Immunohistochemical staining for hMLH1 and hMSH2 was performed on eight of the tumors with MSI-H, five with MSI-L, and 15 tumors without MSI. All eight tumors with MSI-H showed loss of staining for either hMLH1 (n = 5) or hMSH2 (n = 3). In contrast, tumors with MSI-L or without MSI all showed normal hMSH2 and hMLH1 protein expression patterns. Moreover, all eight of the tumors with MSI-H also showed instability at BAT-26, whereas none of the MSI-L tumors or tumors without instability showed instability at BAT-26. These findings suggest that the majority of high-level MSI in gastric cancer is associated with defects of the mismatch repair pathway. Although larger studies are needed, BAT-26 appears to be a sensitive and specific marker for the MSI-H phenotype in gastric carcinoma.

Pathogenesis of posterior capsular opacification Part II: Histopathological and in vitro culture findings

ABSTRACT The most interesting sources of information about the pathogenesis of posterior capsular opacification seem to be histopathological studies and in vitro tissue cultures. Since our surgical technique is extracapsular cataract extraction, the explants we used for tissue culture consisted of the anterior capsule epithelial sheet without the equatorial germinative zone. We successfully overcame several problems by using the autologous plasma clot culture method. This medium, considered the optimal one for this type of culture, allowed us to study the heterogeneous behavior of the epithelial cells in culture. Using the plasma clot culture method, we were able to demonstrate in vitro fibroblastic transformation of the epithelial cells. Histopathological findings of particular cases of posterior capsule opacification and immunohistochemistry of the human lens are also reported.

Neoplastic cells of Hodgkin's disease show differences in EBV expression between Kenya and Italy

The Epstein‐Barr Virus (EBV) has been implicated in the pathogenesis of Hodgkins disease (HD). However, the association of EBV with this disease varies greatly from series to series and from country to country. Epidemiological studies have shown differences in HD occurring in different parts of the world. In particular, it has been reported that HD in developing countries differs from HD in Western countries in terms of epidemiological, pathological and clinical characteristics. These discrepancies among populations suggest an interaction with environmental factors and a direct role of different etiological agents. At present, there are no data on the frequency of association of EBV with HD in equatorial Africa. In this study, a large series of HD cases have been collected at the University of Nairobi, Kenya, and at the Universities of Bologna and Siena, Italy. The cases have been reviewed and classified according to the REAL Classification and the presence of EBV has been assessed by in situ hybridization (ISH). A statistical difference in EBV expression was found between HD from Kenya and HD from Italy. EBV‐positive neoplastic cells were detected in 92% of Kenyan cases, whereas only 48% of Italian cases showed EBER1/2 positivity in the neoplastic cells. Our results suggest that, in Kenya, EBV plays a more direct role in the pathogenesis of HD, as it does for endemic Burkitt lymphoma.

Stage-related differences of mitotic and apoptotic indices, and bcl-2 protein expression in diffusely growing non-Hodgkin's lymphomas

The present study examined whether growth characteristics of diffusely growing non‐Hodgkins lymphomas (NHL) may differ as a function of stage. Among 105 NHL of various types and sub‐types (REAL [Revised European‐American Lymphoma] classification), localized (Ann Arbor pathologic stages I + II) lymphomas exhibited clearly higher indices for mitotic activity, apoptosis and cell turnover, as well as a significantly lower percentage of cells containing immunohistochemically detectable bcl‐2 protein, than disseminated (stages III + IV) NHL. A similar pattern emerged when high‐grade (Kiel classification) lymphomas only were evaluated. Low‐grade NHL showed analogous, but less marked, stage‐dependent characteristics, with the exception of median percentages of bcl‐2+ cells, which remained comparable in all stages. Our findings are consistent with the notion that dissemination of diffusely growing NHL is usually associated with reduced cell turnover and, in high‐grade lymphomas, with the generation of longer‐lived cells.

A case of orbital granular cell tumor (Abrikossof)

Granular cell tumor (Abrikossof tumor) is a rare orbital neoplasm. Its histogenesis is unclear: the cell origin has been proposed from skeletal muscle, histiocytes, fibroblasts, mesenchymal cells, Schwann cells. The authors observed a 58-year-old woman with monolateral exophthalmos and diplopia, caused by a supero-medial orbital granular cell tumor. Tho years after the complete excision, she had no recurrences or metastases. The immunohistochemical findings (negativity to muscular, epithelial, glial, histiocytic and neuronal markers; positivity to S-100 protein and vimentin) confirm the hypothesis of an origin from Schwann cells.

Transitional cell carcinoma of residual kidney after partial nephrectomy for renal adenocarcinoma

Transitional cell carcinoma of the superior calyces was found 1 year after ipsilateral partial nephrectomy for renal adenocarcinoma. The main special features of the case are the rare occurrence of two primary tumours in the same kidney and the previous conservative surgery. A review of the literature has revealed no earlier case of this type.