Abstract

This report describes a tumour in the ileum with clinical features initially suggestive of a gastrointestinal stromal tumour (GIST). Histopathological examination revealed a biphasic tumour in which the spindle cell component showed immunohistochemical evidence of smooth muscle differentiation but without the characteristic profile of a GIST. A well-differentiated epithelial component was also present, comprising glandular structures with immunohistochemical features suggestive of Mullerian differentiation. Similar glandular differentiation has been described in uterine leiomyomas but not, to our knowledge, in tumours associated with the small bowel. None of the characteristic mutations of GISTs were identified in this case. There were no overt features of malignancy but, because of the unusual nature of the case, we assessed the biological behaviour as uncertain.