Genomic imbalance and onco-protein expression of ovarian endometrioid adenocarcinoma arisen in an endometriotic cyst.

BACKGROUND Malignant transformation in endometriosis is a rare but well known complication. However, detailed mechanisms of malignant transition and tumourigenesis in endometriosis remain unknown. We here describe the case of an endometrioid carcinoma arisen in endometriotic ovarian cyst fulfilling Sampson's criteria for malignant transformation of endometriosis. We compared genetic alterations and oncoprotein expression in the endometriotic ovarian cyst and the associated endometrioid adenocarcinoma. MATERIALS AND METHODS Genomic instability was evaluated by comparative genomic hybridization (CGH). Onco-protein expression was analysed by immunohistochemistry with antibodies against bcl-2, c-MYC, cyclin D1, p53, HER-2 and KIT protein. RESULTS CGH revealed a gain of 8q, including the locus of the oncogene c-MYC at 8q24. Immunohistochemistry disclosed a differing protein expression profile between the epithelia of the pre-existing cyst and adenocarcinoma. Apart from HER-2, all onco-proteins were more strongly expressed in epithelial cells of the adenocarcinoma than of the endometriotic cyst. CONCLUSION The solitary genomic imbalance of chromosome 8 possibly reflects the importance for initiation and/or progression of endometrioid carcinoma. Overexpression of onco-proteins then may occur subsequently in the malignant transformation of ovarian endometriosis. However, the exact mechanisms of malignant transition in ovarian endometriosis remain to be elucidated in future studies with a higher number of cases.