Minimally invasive resection of a right atrial mass in a cardiac transplant recipient: a case report.

Intracardiac thrombus formation usually occurs in the left-sided cavities of the heart, most frequently in the presence of atrial fibrillation or cardiomyopathy. We report the case of an initially unclear mass developing in the right atrium (RA) of a heart transplant recipient, which was subsequently resected via a minimally invasive surgical approach. Access via right anterior minithoracotomy using videoscopic assistance allowed for uncomplicated RA thrombectomy in the presented case, avoiding reentry sternotomy with the potential risk of cardiac injury and without aortic cross-clamping or cardioplegic arrest. The patient is doing fine with excellent graft function at the latest follow-up 4 months after minimally invasive thrombectomy and 30 months after cardiac transplantation. To the best of our knowledge, this is the first report describing minimally invasive resection of a right atrial thrombus in a heart transplant recipient.

Microsatellite Instability and hMLH1 and hMSH2 expression analysis in familial and sporadic colorectal cancer.

Immunohistochemical expression analysis of mismatch repair gene products has been suggested for the prediction of hereditary nonpolyposis colorectal cancer (HNPCC) carrier status in cancer families and the selection of microsatellite instability (MSI)-positive tumors in sporadic colorectal cancer. In this study, we aimed to evaluate hMSH2 and hMLH1 immunohistochemistry in familial and sporadic colorectal cancer. We found that immunohistochemistry allowed us to identify patients with germline mutations in hMSH2 and many cases with germline mutations in hMLH1. However, some missense and truncating mutations may be missed. In addition, hMLH1 promoter methylation, commonly occurring in familial and sporadic MSI-positive colorectal cancer, can complicate the interpretation of immunohistochemical expression analyses. Our results suggest that immunohistochemistry cannot replace testing for MSI to predict HNPCC carrier status or identify MSI-positive sporadic colorectal cancer.

Microsatellite instability analysis: a multicenter study for reliability and quality control.

The molecular biology section of the Hereditary Non-Polyposis Colorectal Cancer study group-Germany, instituted a multicenter study to test the reliability and quality of microsatellite instability (MSI) analysis. Eight laboratories compared MSI analyses performed on 10 matched pairs of normal and tumor DNA from patients with colorectal carcinomas. A variety of techniques were applied to the detection of microsatellite changes: (a) silver and ethidium bromide staining of polyacrylamide gels; (b) radioactive labeling; and (c) automated fluorescence detection. The identification of highly unstable tumors and tumors without MSI was achieved in high concordance. However, the interpretation of the band patterns resulted in divergent classifications at several microsatellite marker loci for a large fraction of this tumor/normal panel. The data on more than 30 primers per case suggest that the enlargement of the microsatellite panel to more than 10 loci does not influence the results. In this study, cases with MSI in less than 10% of loci were classified as microsatellite stable, whereas MSI was diagnosed in cases with more than 40% of all markers unstable. We propose that a panel of five microsatellite loci consisting of repeats with different lengths should be analyzed in an initial analysis. When less than two marker loci display shifts in the microsatellite bands from tumor DNA, the panel should be enlarged to include an additional set of five marker loci. The number of marker loci analyzed as well as the number of unstable marker loci found should always be identified. These criteria should result in reports of MSI that are more comparable between studies.