Mohs frozen tissue sections in comparison to similar paraffin-embedded tissue sections in identifying perineural tumor invasion in cutaneous squamous cell carcinoma.

Background: Perineural invasion (PNInv) in cutaneous squamous cell carcinoma (cSCC) increases the risk of recurrence, possibly because of suboptimal identification on frozen or paraffin-embedded tissue sections. Perineural inflammation (PNInf) may portend PNInv.

Objective: We sought to correlate identification of PNInv and PNInf in hematoxylin-eosin-stained Mohs frozen sections with PNInv and PNInf identified in similarly oriented paraffin-embedded sections obtained in cases of cSCC.

Keloid formation occurring in the distribution of a congenital vascular malformation.

A 35-year-old African American man presented with complaints of malodorous drainage from hypertrophic lesions on his occipital scalp (Figure 1, inset). The patient had no family history of keloid formation and no other keloids on his body. The hypertrophic mass on his scalp had been present for 10 years and had not been a result of any type of mechanical, surgical, or laser treatment.