Ted Rosen, MD
Dr. Rosen is Professor of Dermatology, Baylor College of Medicine, Houston, Texas.
Dr. Rosen reports no conflicts of interest in relation to this post.
It is uncommon for a virtual cascade of papers to simultaneously disclose potentially game-changing medical information, especially when physician authors practice in markedly disparate parts of the world. Nonetheless, 2012 brought 3 distinct papers that sharply call into question the accuracy of the standard punch biopsy in determining the subtype of basal cell carcinomas (BCCs). Published online on September 18 in the Journal of the European Academy of Dermatology and Venereology, an Iranian retrospective study of 333 cases disclosed a final pathologic concordance rate between a punch biopsy and subsequent excision specimen of only 72.3%. The authors also noted that in 39.1% (47/120) of aggressive tumors, the initial diagnostic punch biopsy failed to identify an aggressive component (micronodular, infiltrative, or morpheaform BCC).
Strikingly similar results were reported in an American retrospective study of 232 cases that was published in the Journal of the American Academy of Dermatology (2012;66:106-11). In this report, the concordance rate between a punch biopsy specimen and ultimate excisional histology was 72%, and in 40% of aggressive tumors, the punch biopsy failed to identify an aggressive component.
Although the data were reported in a somewhat different manner, another study published online on July 3 in the Journal of the European Academy of Dermatology and Venereology supported the findings of the other 2 citations. In this large Dutch retrospective analysis of 500 primary BCCs (2004-2009), the histopathologic accuracy rate for precise BCC subtype from punch biopsy specimens was calculated to be a scant 69%. Even for superficial BCCs, the punch biopsy was accurate in only 84% of cases, as some of these lesions eventually proved to possess an aggressive component when the entire lesion was subject to definitive excision.
What’s the issue?
Although we may continue to use a punch biopsy to verify the presence of a suspected BCC, taking these 3 recent publications from the Middle East, United States, and Europe together as a body of evidence we also should be reluctant to rely on this type of sampling technique to accurately classify the exact subtype of BCC.
If the punch biopsy demonstrates a low sensitivity and specificity to differentiate aggressive from nonaggressive subtypes of BCC, can we use this biopsy technique to make proper therapeutic decisions? For example, assume that a flat, red, scaly, 2×2-cm patch located on the shoulder is subject to a punch biopsy and the dermatopathologist’s reading is superficial BCC. Can we still treat this lesion with a nonsurgical approach such as photodynamic therapy or imiquimod cream 5%? How can we be sure that there is not an aggressive portion of the lesion that remains undetected and mandates more intensive therapeutic intervention? Consider a classic rodent ulcer subject to punch biopsy with a histologic diagnosis of nodular BCC. Can we be confident that the lesion does not possess a more aggressive component, such as morpheaform BCC, which strongly suggests that Mohs micrographic surgery might be preferable in lieu of simple excision? Even if we complement our clinical judgment with a punch biopsy, how can we best select a treatment option?