Upgrade to more aggressive subtype common in Mohs surgery patients

Patients undergoing Mohs micrographic surgery for aggressive subtypes of nonmelanoma skin cancer were frequently upgraded to a more aggressive subtype before the procedure, according to findings presented at the American Society for Dermatologic Surgery Annual Meeting.

Rachel Braden, MD, a dermatologist at Barnes-Jewish Hospital in St. Louis, and colleagues conducted a prospective study that included 150 patients who underwent Mohs micrographic surgery for nonmelanoma skin cancers. Eligible participants underwent procedures at Barnes-Jewish Hospital between July 2016 and July 2017, and had higher-grade cancer on frozen section at the time of the procedure.

Tumor location and size data underwent independent review, as did the number of Mohs stages to clearance and pathologic features.

Tumors in area H comprised 63% of the malignancies, while 33% were in area M and 4% were in area L.

Infiltrative tumors accounted for 80% of the malignancies with a diagnosis of basal cell carcinoma before the procedure. Of the other basal cell tumors, 44% had metatypical features and 10% were micronodular, according to the results.

Clinicians upgraded 12 squamous cell carcinoma tumors from well-differentiated to moderately or poorly differentiated, while nine squamous cell carcinomas were upgraded from in-situ to invasive.

An increase in tumor size from 1 cm (standard deviation [SD], 0.7) preoperatively to 2.3 cm (SD, 1.2 cm) postoperatively was reported. Patients required 2.1 (SD, 0.7) stages to clearance on average, according to the findings.

Of the three patients with histologically aggressive squamous cell carcinoma who underwent postoperative imaging, two patients subsequently received a diagnosis of metastatic disease.

“A significant portion of cases referred for [Mohs micrographic surgery] at our institution were upgraded to a more aggressive subtype at the time of surgery,” the researchers concluded. “This has important implications for primary dermatologists’ referral practices and Mohs appropriate use criteria guidelines.” – by Rob Volansky

Reference:

Braden R, et al. Histopathologic upgrading of non-melanoma skin cancers at the time of Mohs micrographic surgery: A prospective review. Presented at: American Society for Dermatologic Surgery Annual Meeting; Oct. 5-8, 2017; Chicago.

Disclosures: The authors report no relevant financial disclosures.