Comparative microsatellite analysis in discerning origin of disseminated tumor: The case of a patient with malignant ascites and a history of multiple tumors

The origin of metastatic carcinoma is now always easily resolved on the bas is of conventional clinical and pathological parameters, particularly in pa tients with more than 1 primary tamer. When I of the tumors is a renal cell carcinoma, the clinical picture is further confounded by the tendency of t hese tamers to be locally silent, to metastasize to unusual sites, and to d isseminate long after removal of the primary tumor. We compared tumors for loss (ie, deletion) of loci on chromosomal arms 3p, 5q, 11q, and 18q in a p atient with a malignant ascites fluid, a remote history of renal and coloni c neoplasms, and a strong clinical suspicion of disseminated gastrointestin al adenocarcinoma. DNA from microdissected tumors and normal tissues was su bjected to polymerase chain reaction-based microsatellite analysis. Even th ough the clinical picture suggested a gastrointestinal origin, comparison o f genetic alterations clearly showed that the malignant ascites represented recurrence of the renal cell carcinoma. The malignant ascites and the prim ary renal cell carcinoma showed identical patterns of allelic loss at all l oci tested. In contrast, the malignant ascites and colonic adenoma showed d iscordant patterns of allelic loss, Comparative microsatellite analysis pro vides a rapid genetic approach for discerning the origin of metastatic tumo r spread. This may be a useful diagnostic adjunct when tamer origin is not clear on clinical or morphological grounds, In some instances, it may even provide a reasonable alternative to an extensive and costly conventional wo rk-up. HUM PATHOL 30:1111-1113. Copyright (C) 1999 by W.B. Saunders Company .