A composite score that includes histopathologic features of perineural invasion (PNI) can predict adverse outcomes in cutaneous squamous cell carcinoma (cSCC), according to a study published in the April issue of Dermatologic Surgery.

Mariam B. Totonchy, M.D., from the Yale School of Medicine in New Haven, Connecticut, and colleagues conducted a retrospective cohort study involving 45 patients with cSCC and PNI treated with surgical excision to identify histopathologic features that may be associated with adverse outcomes. Histopathologic slides were analyzed for largest affected nerve diameter, number of nerves affected, depth of nerve involvement, intratumoral versus extratumoral PNI, and focal versus circumferential PNI.

The researchers found that the median largest affected nerve diameter was 0.13 mm, and there were a median of four nerve structures involved. Six patients developed adverse outcomes after a median follow-up of 24 months, including two local recurrences, four metastases, and two tumor-related deaths. Nerve diameter and number of affected nerves were significantly associated with adverse outcomes in a univariate logistic regression analysis. The strongest predictor of adverse outcome was a composite PNI score, calculated from five histopathologic features.

"A larger, multicenter study to validate the five measures of PNI severity and the composite PNI scoring system will be helpful to refine cSCC prognosis and integrate this PNI score with current staging systems," the authors write.

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