SMAD4 and rectosigmoid junction neoplasm: Sequencing of 4 primary LGSC samples (including 2 from the pelvic tumor, 1 from the rectosigmoid tumor and 1 from a peri-aortic tumor nodule) and 2 recurrent LGSC samples (both from the abdominal wall tumor) revealed somatic non-synonymous mutations in both BRAF (chr7:140,453,136A > T, V600E) and SMAD4 (chr18:48,591,918C > G, R361G).