Histopathological Concordance Rate between Punch Biopsy and Excision in Basal Cell Carcinoma

Background: Accuracy in histological subtyping of basal cell carcinoma (BCC) is crucial for determining the appropriate treatment modality. Previous studies have assessed the concordance rateof punch biopsy and excision in subtyping BCC however, they did not calculate this rate according to the BCC location or in Asian populations. Objective: This study compared the concordance rate of punch biopsy and excision for each BCC location. Methods: This study included 192 patients who underwent both punch biopsy and excision. BCC subtypes identified by punch biopsy and excision were compared to calculate the concordance rate. The differences in the rates of misdiagnosis according to the BCC location were also determined. Results: The overall concordance rate of punch biopsy and excision was 78.1% (150/192). The proportion of aggressive type was higher for excision than for punch biopsy. The false-positive rate, defined as the rate of misidentified nonaggressive type, was 19.7% (26/132) and was highest for nodular-type BCC. Additionally, most discrepancies occurred in BCCs located in the face, especially in the H-zone. Conclusion: Owing to the inconsistencies in the results of punch biopsy and excision and the high false-positive rate of punch biopsy, dermatologists should be aware of the possibility of an aggressive type BCC even if it is identified as anonaggressive type in punch biopsy. Moreover, more aggressive treatment should be considered in cases of BCCslocated on the face, especially in the H-zone, as the discrepancy rate is higher. (Korean J Dermatol 2020;58(2):97∼101)