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Incidental perineural invasion in cutaneous SCC associated with poor prognosis

Although uncommon, incidental perineural invasion in cutaneous squamous cell carcinoma was associated with clinicopathological indicators of poor prognosis, according to recent study results.

Researchers conducted a multicenter prospective analysis of 653 patients with 753 cases of cutaneous squamous cell carcinoma (SCC) treated with Mohs micrographic surgery. Thirty-three patients (mean age, 78 years; 72.7% men) had incidental perineural invasion (PNI) in 35 cutaneous SCC cases (incidence, 4.6%), while 620 patients (mean age, 75 years; 71.3% men) showed no PNI in 718 cutaneous SCC cases.

Head and neck (P=.039) and scalp and temple (P=.018) tumors, larger tumor diameter (P<.001), presence of clinically palpable lymphadenopathy (P=.012) and recurrent and painful tumors (P<.001, both) were associated with PNI. Poor tumor differentiation; greater mean tumor thickness and Clark level V or greater; and higher number of Mohs stages and larger estimated maximum Mohs margin required for tumor clearance also were associated with PNI (P<.001, all).

Researchers said tumor thickness and degree of tumor differentiation were risk factors for aggressive cutaneous SCC, and incidental PNI was associated with both factors (P<.001).

Study limitations included the paucity of patients demonstrating incidental PNI.

“Although incidental PNI is an uncommon feature of [cutaneous] SCC, it was found to be associated with previously established markers of poor prognosis, including tumor size, tumor depth, clinical risk factors and significant subclinical extension,” the researchers concluded. “To this end, the association of incidental PNI with markers of poor prognosis suggests that it may be a covariable in the clinical course of [cutaneous] SCC.

“Our findings suggest that documenting incidental PNI in histologic specimens may serve as a marker to improve the prognostic assessment of patients for future studies and provide vital information regarding clinical settings one may expect to see PNI.”

Disclosure: The researchers report no relevant financial disclosures.