Basal cell carcinoma with perineural invasion: A prospective study examining subtype, tumor surface diameter, invasion depth, and anatomic site in 3005 consecutive cases.

Background: Basal cell carcinoma (BCC) may present with or without perineural invasion (PNI). We reviewed BCC for PNI by subtype, microscopic tumor surface diameter, invasion depth, and anatomic site.

Method: Consecutive excisions were prospectively collected in an Australian center 2016-2018.

Results: Total cases were 3005 including 40 with PNI: 28 in males, 12 in females. Superficial and nodular subtypes had no PNI. As the percentage tumor mass of infiltrative BCC increased beyond 90% the presence of PNI substantially escalated (OR7.0). Comparing PNI absent or present the respective maximum mean tumor microscopic surface diameters ranged from (95%CI [9.6-10.0] P < .001) to 11.2 mm (95%CI [9.4-13.0] P = .59). Respective maximum mean invasion depths were from 1.0 mm (95%CI [0.98-1.05] P < .001) to 2.3 mm (95%CI [1.8-2.7] P < .001). Respective maximum mean invasion depths were from 1.0 mm (95%CI [0.98-1.05] P < .001) to 2.3 mm (95%CI [1.8-2.7] P < .001) to 2.3 mm (95%CI[1.8-2.7] P < .001). Males recorded most PNI on the scalp, followed by cheek and chin. Patients with more than two BCC cases had a greater proportional PNI risk (OR3.7). Mean PNI nerve diameters were 0.06 mm (males) and 0.03 mm (females).

Conclusion: Increases in percentage infiltrative subtype within the tumor mass, microscopic tumor diameter, tumor invasion depth, and BCC cases per patient all recorded more PNI. Minimum invasion depths with PNI were 1.0 mm on males (nose) and 1.0 mm females (forehead).