Innovative 19-minute rapid cytokeratin immunostaining of nonmelanoma skin cancer in Mohs micrographic surgery.

Background: Dense inflammation can obscure nonmelanoma skin cancer (NMSC) on frozen sections, prompting removal of additional layers to ensure negative margins. Cytokeratin (CK) immunostaining in Mohs micrographic surgery (MMS) has been examined and found to be useful but is limited by lengthy 1-hour processing.

Objective: Our objective was to develop an effective ultrarapid CK frozen section immunostain to be used during MMS in cases of NMSC with dense or perineural inflammation.

Methods: An ultrarapid immunostain with a mixture of AE1/AE3 monoclonal antibodies was performed in 21 MMS cases and compared with permanent sections prepared from the same material.

Results: The ultrarapid CK protocol stained all of the cells in each of the 21 examples of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) in frozen tissue in a way equivalent to immunostains being applied to permanent sections.

Conclusion: The 19-minute CK immunohistochemistry protocol in frozen tissue appears to be as effective at labeling tumor cells of SCC and BCC as methods requiring permanent sections. It is hopeful that this technique may prevent recurrences after MMS and limit the number of Mohs layers required to obtain free margins when inflammation is abundant. It also is effective in uncovering subtle perineural invasion.