Grading of Non-Melanoma Skin Cancers: Mohs Micrographic Surgery vs. Initial Biopsy
Posted: Thursday, September 5, 2019
Diagnosis of aggressive non-melanoma skin cancers can be missed on initial biopsy results, according to a study by Rachel L. Kyllo, MD, and colleagues, of the Washington University School of Medicine, St. Louis. Published in the Journal of the American Academy of Dermatology, the study’s findings suggest that the depth and type of biopsy, in addition to patient characteristics, should be considered prior to definitive treatment.
In this prospective, single-center, cross-sectional study, tumor specimens that had been graded after superficial shave (98% of cases), punch, excisional, or curette biopsy were referred for frozen section pathology analysis via Mohs micrographic surgery. Tumors belonged to patients who were on average 71 years of age, predominantly men (59%), with fair skin (mostly skin types 1 or 2). Two fellowship-trained surgeons interpreted all frozen sections according to standard practices.
Both providers consistently upgraded about 10% of the 2,578 tumors referred in this study, from a less-aggressive subtype determined during initial biopsy. A total of 15% of the 1,563 basal cell carcinomas were upgraded, as well as about 3% of the 351 squamous cell carcinomas in the study. Moreover, in two cases, the diagnosis based on initial biopsy was incorrect: a basal cell carcinoma was diagnosed as a squamous cell carcinoma, and vice versa. Upgraded tumors required extensive surgery and were larger than nonupgraded tumors, with a larger degree of size change after operation. Lastly, 11% of tumors that were upgraded belonged to patients who were immunosuppressed.
“Dermatologists should consider the limitations of superficial biopsies for detecting aggressive histology when weighing treatment options,” concluded the authors.
Disclosure: The study authors reported no conflicts of interest.