Verrucous carcinoma (VC) is a variant of squamous cell carcinoma (SCC), characterised by its inability to metastasize. In contrast, hybrid carcinomas, composed of VC and foci of conventional SCC, harbour a metastatic potential. Correct pathohistological diagnosis is therefore crucial for the choice of treatment. There is mounting evidence that desmosomes are involved in several aspects of carcinogenesis. Previous studies have shown an altered expression of desmosomal components in conventional SCC, which was associated with tumour behaviour, but no data have been found on desmosomes in VC. We therefore analysed the expression of desmosomal components in biopsy samples of 21 cases of VC and 5 cases of hybrid carcinoma of the head and neck in comparison to 23 cases of conventional SCC and 47 samples of normal squamous epithelium of similar localisation, using immunohistochemistry and real-time reverse-transcription polymerase chain reaction. We found that the expression patterns of desmosomal components in VC were fairly similar to those in normal epithelium but differed significantly from those in conventional SCC. Immunohistochemical reactions against desmosomal components disclosed the foci of SCC in hybrid carcinomas. In conclusion, we believe that expression patterns of desmosomal components in VC are consistent with its less aggressive behaviour. Differential expression of desmosomal components between VC and SCC makes some desmosomal components potentially useful in the diagnostics of VC, especially for the detection of hybrid carcinoma.
