Squamous cell carcinoma arising in mature cystic teratoma of the ovary: report of two cases with molecular analysis.

Mature cystic teratoma (MCT) is the most frequent ovarian tumor and it is generally composed of well-differentiated elements which, nevertheless, have the potential for malignant transformation. The authors report two cases of squamous cell carcinoma (SCC) arising on ovarian MCT. In the present study, no mutation of the CDKN2A gene, whose impairment may deeply affect either the p16(CDKN2A)-CyclinD1-pRb cascade or the p14(CDKN2A)-mdm2-p53 cascade, was observed in tumour tissues from our cases' collection. This suggests that changes in the protein levels for the above-described candidate effectors may be somehow due to epigenetic alterations into the mechanisms controlling their expression. Analogously, no genetic modification among the two main genes (EGFR and KRAS) upstream the MAPK signalling pathway, which has been widely reported to play a major role in both development and progression of vast majority of malignant tumours, was detected in this series. Additional genes and pathways should be therefore investigated in order to identify genomic impairments underlying the MCT malignant transformation.