Oral variant of acantholytic squamous cell carcinoma-Histochemical and immunohistochemical features

Acantholytic squamous cell carcinoma (ASCC) is an uncommon variant of squamous cell carcinoma (SCC). It is characterized by a combination of typical SCC and pseudoglandular structures, dyskeratotic cells and prominent acantholysis. The purpose of this study was to analyze the histochemical and immunohistochemical characteristics of the intraoral variant of ASCC. Cases of intraoral ASCC were retrieved from the English language literature. Four new cases from our files were added. In total, 35 cases were included and analyzed in this study. The mean age of the patients was 61.5 + 13 years (age range 38-92 years), with a male-to-female ratio of 1.7:1. According to the available data, histochemical and immunohistochemical stains for mucins were found to be consistently negative. E- cadherin, a marker of adherens junctions, was usually reported to be expressed in areas of "typical" (non acantholytic) SCC, but reduced in the acantholytic areas. We examined for the first time the expression of claudin 1, a marker of tight junctions, and found it to be reduced in the acantholytic areas, similar to E-cadherin. Several cases of oral ASCC also expressed vimentin and cytokeratin (CK) 19, markers associated with epithelial-mesenchymal transition. A wide range of non-epithelial markers yielded negative immunoreactions. In conclusion, ASCC is an uncommon variant of squamous cell carcinoma. The acantholytic process appears to involve reduced expression of molecular components of both adherens junctions and tight junctions. These findings could suggest a relation to the epithelial mesenchymal transition process and therefore further studies are needed in order to establish such a link and the subsequent possible impact on the clinical outcome of the patients.