Table 2.
Distinguishing features between CC and its important differential diagnoses
Microscopic features |
Carcinoma cuniculatum | Verrucous carcinoma | Conventional Squamous cell carcinoma | Pseudoepitheliomatous hyperplasia |
---|---|---|---|---|
Architecture | Well differentiated squamous lined keratin-filled, burrowing crypts | Mixed exophytic and endophytic growth pattern. Verruciform exophytic component | Solid, irregular nests/islands, squamous pearls may be present | Markedly acanthotic irregular squamous epithelium |
Invading front | Deeply located cohesive squamous nests and cryptsa | Broad “pushing” infiltration | Aggressive stromal invasion with desmoplastic response | Tongue-like projections of squamous epithelium. Absence of stromal desmoplasia |
Lymphovascular invasion | Not present | Not present | Possible | Not present |
Cytologic atypia | Absent to mildb | Absent to mildb | Mild to severe | Absent to mildb |
Mitotic activity | Variableb | Variableb | Frequent and atypical | Variable, non atypical |
aMay have superimposed pseudoepitheliomatous hyperplasia, displaying a reticulated network of tongue-like epithelial protrusions resulting in a jagged tumor–stromal interface mimicking aggressive stromal invasion
bThe degree of cytologic atypia and basally confined mitotic activity may be increased in acutely inflamed areas