Background: Adenoid cystic carcinoma (AdCC) displays morphological diversity within its characteristic tumor cell nests, which are primarily classified into tubular, cribriform, and solid patterns. Such histological diversity should result from the proportional proliferation between neoplastic myoepithelial cells (NMC)/basal cells and ductal epithelial cells. The aim of this study was to clarify the relationship between this morphological diversity and the development of AdCC in the salivary gland using double immunostaining with monoclonal antibodies to p16 and p63 gene products. Methods: We examined 10 samples of formalin-fixed, paraffin-embedded AdCC tissues. Results: In the normal salivary gland, p16 protein (P16) was not expressed in any cells, whereas p63 protein (P63)-positivities were observed in ductal basal cells and in acinar myoepithelial cells. In AdCC foci showing the tubular pattern, P16 expression was localized in the inner cells of the ductal structure, while P63 was localized in the outer NMC of them within the same sections. In tumor foci with the cribriform pattern, P16 was expressed in several cells forming pseudocysts and in some of the inner cells. P63 was expressed in many cells in the cancer nests. In those with the solid pattern, P16 and P63 were intermixed within the same foci. Conclusions: Thus, the double immunohistochemistry for P16 and P63 was useful for observing the morphological diversity of AdCC cells within the same foci on the same tissue section. These data suggest that P16 and P63 may play important roles in the morphological diversity and development of AdCC tissue architectures.
Read full abstract