Depth of Invasion of Aggressive and Nonaggressive Basal Cell Carcinoma

Objective: Dermal invasion is characteristic of more aggressive basal cell carcinoma (BCC) tumors. However, reporting the depth of invasion of BCC is not currently a standard or recommended practice. The purpose of this study was to document the depth of invasion of BCC. Design: Original hematoxylin and eosin-stained slides of biopsied BCCs (N=500) were reviewed. The depth of invasion was measured for each case. Each case was also determined to be aggressive or nonaggressive based on the presence of additional histologic features. Setting: Biopsy specimens from a large private practice were reviewed. Measurements: Descriptive statistics were calculated for all cases. To compare the average depth of invasion of cases with aggressive features versus cases with nonaggressive features, two-tailed, independent t-tests were computed. Results: The overall median depth of invasion was 0.68mm (range: 0.10-5.49). The median depth of invasion of aggressive cases (n=68) was 1.04mm, while the median depth of invasion of nonaggressive cases (n=432) was 0.62mm. The difference between median depth of invasion of aggressive and nonaggressive cases was found to be significant (p<0.0001). This significant difference (p<0.0001) was maintained even with transection, which was present in the majority of cases (n=347; 69.4%). Conclusions: Dermal invasion depths of all subtypes of BCC have not been previously reported. The median dermal invasion of histologically aggressive BCC is greater than nonaggressive tumors. These findings might help clinicians in determining the depth of biopsy and choice of treatment.