CD30+ cells in regressing keratoacanthoma and in non-keratoacanthomatous squamous cell carcinoma

In a previous report, we demonstrated how a percentage of CD30+ cells was nearly constant in the inflammatory infiltrate that accompanies keratoacanthoma (KA), but we saw a lack of CD30 cells when KA was regressing. In the current study we investigated the presence of CD30+ cells in the inflammatory infiltrate of regressing KA as well as in well-differentiated squamous cell carcinomas of non-keratoacanthomatous type. We examined 80 keratoacanthomas from our archives, and selected those with the pattern of advanced regression. We also examined 14 well-differentiated non-KA type SCCs from our archives. In all the cases, we performed a immunohistochemical study for CD30. Of the 80 KAs, 6 cases (7.5%) showed the pattern of regression. While the mean of the percentages of CD30+ cells in the infiltrate was 0.58 for the regressing KAs, it was 1.77 for SCCs. While cells with the paranuclear-dot pattern of immunostaining plus membranous pattern of immunostaining could be easily found in SCC cases, cells only with membranous expression of the marker were the rule in KA. We conclude that CD30 positive cells might play a role in KA regression (Tab. 2, Fig. 4, Ref. 24).