SAN DIEGO – Evidence of chronic inflammation noted during Mohs surgery is a telltale sign of perineural invasion.
"If you see chronic inflammatory infiltrate within or proximal to a neurovascular bundle, look for perineural tumor," said Dr. Alexander Miller, a dermatologic surgeon in private practice in Yorba Linda, Calif. Histologically, that means abundant lymphocytes and perhaps histiocytes.
2002 The University of Texas M. D. Anderson Cancer Center
Perineural invasion in squamous cell carcinoma of the lip.
An abundance of neutrophils, however, is likely indicative of an acute inflammatory response. Perhaps even a response resulting from electrocautery during a Mohs procedure.
Neutrophils might also be present if a keratinizing tumor has ruptured into stroma, generating a microabscess. "But then it’s pretty darned obvious what you have," said Dr. Miller at a meeting sponsored by the American Society for Mohs Surgery.
Finding perineural tumor cells within a cluster of inflammatory cells can be like hunting for the proverbial needle in a haystack. A low-power view might miss them, he said. On medium or higher power views, tumor cells may appear as minute dots, a tiny stripe, or a sliver along one edge of a nerve.
To demonstrate, Dr. Miller displayed a slide depicting voluminous chronic inflammation surrounding an artery, vessel, and nerve.
"No tumor," he said.
"But if one looks carefully, two sections down, same slide, same patient, lo and behold there’s the tumor. Complacency should not be had here. One has to ensure that particularly when there’s inflammation, one needs to look very carefully at all sections of the slide."
Dr. Miller reported having no financial disclosures relevant to his talk.