The differentiation of pseudoepitheliomatous hyperplasia from invasive squamous cell carcinoma is a difficult and frequently encountered distinction, especially in biopsy specimens from head and neck mucosa. The problem is compounded by inflamed and often poorly oriented tissue sections.
To distinguish pseudoepitheliomatous hyperplasia from invasive squamous cell carcinoma, utilizing a panel of antibodies to various epithelial and stromal elements (p53, matrix metalloproteinase 1, E-cadherin, and collagen IV) that has been shown to be useful in differentiating intestinal adenomas with invasive adenocarcinoma from displaced adenomatous epithelium.
Thirty-three archival specimens (16 squamous cell carcinoma [12 with invasion and 4 with microinvasion] and 17 pseudoepitheliomatous hyperplasia) from head and neck mucosal locations were immunostained and examined by the authors.
We found increased nuclear staining of the invasive tumor cells with p53. There was decreased staining within invasive tumor nests with E-cadherin. There was highly significant increased staining within tumor cells and adjacent stroma with matrix metalloproteinase 1 (P < .001). The only antibody in our panel that did not show a reliable staining pattern was collagen IV. It appeared fragmented in benign inflamed and malignant areas and therefore was not useful.
p53, matrix metalloproteinase 1, and E-cadherin showed significant staining trends independent of inflammation and suboptimal tissue orientation. Although a properly oriented hematoxylin-eosin-stained section was our gold standard, we found this immunoperoxidase panel useful as a diagnostic adjunct in difficult cases.