Figure 5: VR-SIM image of the posterior surface of Case 14, with a pathologically-confirmed positive surgical margin with perineural invasion.

(a) Full surface image of the posterior side, with orientation provided by the directional arrows. Areas of interest on the right and central posterior surface are indicated by the dashed yellow boxes. (b,c) Areas of perineural invasion observed on the VR-SIM image. Small dense cancer glands (yellow arrows) are observed tracking along a prominent nerve (white arrows). (d) Histological cross-section from the right posterior quadrant, indicating the presence of malignant glands touching the inked surgical margin, as well as the presence of perineural invasion (glands wrapping around a nerve). (e) Large area of perineural invasion observed on VR-SIM, with small, dense, highly cellular glands (yellow arrows) tracking along nerve fibers (red asterisks). (f) Small, rounded and elliptical glands with malignant appearance (yellow arrows) on the VR-SIM image and (g) histological section of malignant glands at the inked surgical margin (black arrows), but not associated with nerve tissue.