Histopathological discrepancy between biopsy and Mohs micrographic surgery in keratinocyte carcinoma: A 464 case...

Therapeutic approaches to keratinocyte carcinoma rely on the accuracy of the biopsy to correctly identify, grade or subtype the tumour. Several studies have investigated the frequency and nature of histopathological discordance between the biopsy and final excision specimen. We analysed information extracted from an Australian Mohs micrographic surgery (MMS) database and compared similar studies.

An Australian MMS database was retrospectively reviewed for a period of one year. Correlation was made between the preoperative lesion diagnosis based on the formal pathology report and the histopathological results reported at the time of MMS. A systematic PubMed review of similar articles was also performed.

A total of 464 cancers (406 BCC and 58 SCC) in 399 patients were included. The overall discrepancy rate in the histopathological classification of keratinocyte carcinoma in our study (42.2%) and the proportion of cases in which the biopsy underestimated the aggressiveness of the tumour (12.9%) were consistent with those found in similar studies. The percentage of biopsies that failed to identify an aggressive BCC subtype (31.6%), and that of biopsy-proven superficial BCC that demonstrated an invasive component in MMS (79.3%), were higher in our study than in comparable studies. The high prevalence of mixed histopathological subtypes, especially amongst BCC with discordant histopathological results, appeared as an important contributing factor.

Despite subtle differences, the results from this Australian study support the results from similar studies and highlight that the biopsy report should be carefully interpreted in combination with the clinical findings.