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Nonmelanoma skin cancers may be more aggressive than initial biopsy suggests

A significant proportion of nonmelanoma skin cancer cases referred for Mohs micrographic surgery showed histologic features of aggressive cancers that were not apparent on the initial biopsy, according to research in Journal of the American Academy of Dermatology.

“Clinicians should consider the importance of sampling an adequate amount of tissue to enable accurate diagnosis when one of these aggressive subtypes, which are associated with increased risk for recurrence, are suspected,” Rachel L. Kyllo, MD, from the division of dermatology at Washington University School of Medicine, St. Louis, and colleagues wrote.

Nonmelanoma skin cancer (NMSC) tumors that have been upgraded in subtype require significantly more stages and specimens for tumor clearance, they wrote.

Patients from the Center for Dermatologic and Cosmetic Surgery at Washington University from July 2016 through June 2017 underwent Mohs micrographic surgery (MMS) for basal cell carcinoma (BCC), squamous cell carcinoma (SCC) or SCC in situ. Of 2,578 tumors treated during the study period, 265 tumors (10.3%) from 253 patients were upgraded on frozen-section analysis during MMS to a more aggressive subtype, the study said.

Seven percent of upgraded cancers were recurrent tumors, according to the study. The average delay from biopsy to MMS was 111 days, and 98% of the biopsies were performed using a shave method.

“There is ... substantial variation in surgical technique within a shave biopsy, and deeper saucerization biopsies are probably more accurate than superficial shave biopsies at identifying aggressive histologic subtypes of NMSC,” the researchers wrote.

In BCCs, 230 of 1,563 cases (15%) were upgraded to a more aggressive subtype. Infiltrative and metatypical were the most common subtypes, and many tumors contained more than one subtype. The upgrade rate was 3% for SCC and SCC in situ.

In upgraded lesions, the postoperative defect size was significantly larger at 2.4 cm compared with nonupgraded lesions at 1.7 cm for BCC and 2.5 cm vs 1.8 cm for SCC in situ.

Researchers found no significant differences in tumor location in BCC. SCC had a tendency toward a higher proportion of upgraded tumors on the head and neck.

A complicated surgery was classified as one necessitating flap or graft repair; 40% of upgraded tumors required a complicated repair compared with 15% of nonupgraded tumors.

Immunosuppressed patients with SCC have an increased risk for recurrence and nodal metastasis, which should be considered when determining treatment options in these patients, the researchers added.

One of the study limitations was that the results represent the experience from one academic center over a 1-year period, which may be influenced by referral bias and surgical referral practice patterns. – by Abigail Sutton

Disclosures: The authors report no relevant financial disclosures.