PALM DESERT, CALIF.An immunoperoxidase stain for cytokeratin 7 can be extremely helpful for reducing recurrences when performing Mohs surgery on patients with extramammary Paget's disease, Dr. John Zitelli said at the annual meeting of the American Society for Dermatologic Surgery.
"Although I don't have enough patients in the last 2 years to give you long-term follow-up, there is no doubt in my mind that this is the way to go," Dr. Zitelli said.
Without the stain, a review that included his own patients treated over a period of 20 years showed a recurrence rate of about 20%, said Dr. Zitelli, a former president of the American College of Mohs Micrographic Surgery and Cutaneous Oncology who practices in Pittsburgh.
Although all of the patients who had recurrences did well eventually, the recurrence rate probably indicates that he was missing individual Paget cells around the nests of tumor of the main lesion. The stain makes those individual cells in a frozen section easy to see without extra magnification, he said.
Cytokeratin 7 is a filament protein expressed by cancers in the epithelia.
"My kids could see it," he said of stained, individual cells in a section.
The staining technique using the cytokeratin 7 stain requires only 1 hour, so a case requiring multiple stages can be done in a single day, he added.
To remove Paget's disease using the Mohs technique, Dr. Zitelli uses the exact same method he helped develop for MART(melanoma antigen recognized by T cells)-1 staining of melanoma (Dermatol. Surg. 2004;30:4038).
He also uses a "strip technique" in part because the lesions tend to be rather large (2030 mm in diameter), which can make them difficult to section. With this technique, he outlines the lesion before cutting. His first stage is to take the margin around where he has marked. Once the margins are clear, he goes back and takes the central island of tissue, and all tissue is taken down to the fat.