Intrathoracic sporadic desmoid tumor with the beta-catenin gene mutation in exon 3 and activated cyclin D1

We report a case of intrathoracic desmoid tumor without familial adenomatous polyposis and demonstrate betacatenin mutation of exon 3. A 15-year-old male presented with a desmoid tumor after having sustained an assault. In an examination for a mutation of the beta-catenin gene, an activating mutation from ACC ( Thr) to GCC ( Ala) at codon 41 was found. Immunohistochemical staining showed that accumulated beta-catenin protein was predominantly localized in the nuclei of desmoid cells, and cyclin D1 protein was also overexpressed. These findings might suggest that an activating mutation of the beta-catenin gene affected regulation of the cyclin D1 gene, resulting in the generation of intrathoracic sporadic desmoid tumor, which arose at the site of posttraumatic injury. Copyright (C) 2006 S. Karger AG, Basel.