Basal cell carcinoma characteristics as predictors of depth of invasion

Background: Pretreatment risk stratification of basal cell carcinoma (BCC) is largely based on histologic subtype reported from biopsy specimens. Objective: We sought to determine the degree of concordance between characteristics identified on biopsy specimen and excision and to determine if histologic characteristics other than subtype correlated with depth of invasion. Methods: Histologic specimens of 100 BCC biopsy specimens and corresponding excisions were reviewed. Anatomic site, histologic subtype, maximum depth of extension, contour of the lobules at the leading edge, elastosis characteristics, presence of necrosis, calcification, and ulceration were recorded. Concordance between biopsy specimens and their excisions with relation to depth of tumor lobules was analyzed. Results: The concordance between the subtype of biopsy specimen and excision was 62%. Micronodular tumors had the greatest mean depth, followed by infiltrative, nodular, and superficial subtypes. Subtype reported from biopsy specimen (P =.0002) and excision (P <.0001) correlated to depth and was superior to age, contours of excision specimens, the presence of necrosis, and the extent of excisional solar elastosis. Gender, anatomic site, contours of biopsy specimens, elastosis color, elastosis type, the presence of ulceration, and calcification did not correlate with depth. Limitations: Selection bias is present as only standard excisions were included; BCCs treated by other methods were not examined. Conclusions: BCC subtype identified on biopsy specimen may not correlate with subtype identified on excision. Morphologic subtype has the highest correlation with depth and reporting should reflect the highest risk growth pattern if a biopsy specimen contains more than one pattern. Consideration should be given to reporting necrosis and degree of solar elastosis.