Cdx2 gene expression in mucinous benign ovarian tumours of intestinal type [Espressione del gene cdx2 nei tumori ovarici mucinosi benigni di tipo intestinale]

Introduction: Cdx2 gene belongs to the homeobox caudal gene family and it is located, in humans, on the 13q12.3 chromosome; in particular it codifies for a specific nuclear transcription factor which induces intestinal epithelium development, differentiation and preservation. Cdx2 expression in the human embryo can be observed in the intestinal epithelium starting from the sixth week of gestation. In the foetus and in adults it is observed in the whole enteric tube from the duodenum to the anal canal. Because of its organ specificity, cdx2 is an important marker for metastatic neoplastic lesions. Cdx2 is expressed in intestinal metaplasia and it is focally positive in adenocarcinomas of intestinal type of the stomach, pancreas and gall bladder as well as in ovarian mucinous adenocarcinomas. Finality of the study: The aim of our study is to detect cdx2 positivity, with evaluation of its characteristics and expression, in ovarian mucinous cistoadenomas. Materials and Methods: We examined cdx2 expression in 50 ovarian mucinous cistoadenomas (mean age between 17 and 85), 19 of which were localised in the right ovary while 31 in the left one. Standard staining techniques (H&E), histochemistry (AB-PAS) ed immunohistochemistry with monoclonal antibodies against cdx2 (Biogenex/Menarini cdx2-88, batch MU3920402XS) were performed on formalin fixed and paraffin embedded material. For each case two samples were analised. Results: Morphological evaluation of the 50 benign mucinous tumours distinguished 47 of endocervical type and 3 of intestinal type. These data were also confirmed by characterisation of mucin profile by AB-PAS staining. Using anti-cdx2 antibodies tumours of endocervical type were negative, while 3 intestinal type tumours were positive. In particular 2 cases presented diffuse nuclear positivity, while in one positivity was only focal. Discussion: Until today only two studies deal with cdx2 expression in mucinous ovarian tumours: 5 and 14 cases strong respectively. In the former, cdx2 expression was positive in all cases (100% positivity - 5/5), in the latter cdx2 expression was positive in 64% of cases (9/14). In order to explain the lack of consistency in these data one must analyse ovarian mucinous tumours in detail. These neoplasms are divided into two subtypes: endocervical type and intestinal type. Distinction between these two types is near to impossible in malignant tumours, difficult in bordeline tumours while it becomes easy in benign ones. Among benign tumours, endocervical type tumours are the majority, while intestinal type are much more infrequent. Our 50 case strong casistic is sufficiently ample to include 3 cases of intestinal type, all of which are cdx2 positive, compared to a complete negativity in the remaining 47 tumours clearly of endocervical type. We believe that the lack of consistency between the afore mentioned studies is probably due to the fact that neither work contemplates the subdivision in intestinal and endocervical types. It is hence possible to hypothesise a selective and specific correlation between cdx2 positivity and the intestinal type epithelial component of ovarian tumours.