cSCC tumors upgraded during Mohs micrographic surgery often more challenging

Cutaneous squamous cell carcinomas that were upgraded during Mohs micrographic surgery were more likely to present clinical challenges, according to a study.

“Initial biopsies of cutaneous squamous cell carcinomas (cSCC) may not reveal aggressive histologic features, which would otherwise inform appropriate surgical management and patient education,” Esther Chung, MD, of the division of dermatology at Washington University School of Medicine, St. Louis, and colleagues wrote.

In the retrospective cohort study, the researchers assessed the incidence of and risk factors for histopathologic “upgrading” of cSCC in 1,558 tumors treated with Mohs micrographic surgery (MMS). Upgrading was defined as “a lesser degree of differentiation (poor or moderate) and/or bony or perineural invasion identified during MMS that was not reported in histopathologic evaluation of the initial biopsy.”

Eligible participants had invasive cSCCs treated between 2017 and 2019 at a single academic institution.

Results showed that 115 (7.4%) of the eligible tumors were upgraded during surgical intervention.

Using multivariable analysis that controlled for surgeon differences, among other variables, the researchers found that tumor upgrading was significantly predicted by male sex (OR = 1.82; 95% CI, 1.10-3.01; P = .020), prior field treatment (OR = 2.02; 95% CI, 1.22-3.36; P = .007), rapid growth of cSCC (OR = 2.49; 95% CI, 1.23-5.05; P = .012) and location on the ear or lip (OR = 2.31; 95% CI, 1.24-4.28; P = .008). Tumor diameter also affected likelihood of upgrading, with risk elevated in those 2 cm or greater and less than 4 cm (OR = 4.77; 95% CI, 2.99-7.63; P < .001) and those 4 cm or greater (OR = 5.97; 95% CI, 1.64-21.71; P = .007).

Other findings showed that upgraded tumors had an increased likelihood of “subclinical spread,” which the researchers defined as requiring three or more Mohs surgical stages to clear (OR = 3.12; 95% CI, 1.77-5.49; P < .001). Moreover, larger differences between pre- and postoperative areas also were observed in upgraded tumors (OR = 1.21; 95% CI, 1.15-1.28; P < .001).

Complicated closure procedures were also required for upgraded tumors, including flap or graft or referral to another specialty for outside repairs, according to the findings.

The study was limited by its single-center, retrospective nature, along with interrater variability.

“A significant proportion of cutaneous squamous cell carcinomas are histopathologically upgraded from the initial biopsy during Mohs micrographic surgery,” the researchers wrote, noting that these tumors can be more challenging to manage. “Dermatologists may use patient and tumor characteristics to identify high-risk patients for tumor upgrading, plan appropriate surgery and provide optimal patient counseling.”