_:vb50953651 . _:vb50953651 "A gastrointestinal system benign neoplasm that derives_from smooth muscle cells and that is located_in the anus."^^ . _:vb50953651 . _:vb50953651 . _:vb50953651 "url:https://www.ncbi.nlm.nih.gov/pubmed/9187805"^^ . _:vb50953651 . _:vb50953651 .