Basal cell carcinoma characteristics as predictors of depth of invasion

This article is in press in JAAD. I believe it highlights two points, firstly that concordance between biopsies and excisions in only 62% and, secondly, that subtype was best predictor of depth.

regards

Ian

 

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.

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  1. #1 by Tony Dicker on May 10, 2012 - 1:17 am

    The concordance is the interesting part of this article. Of 82 lesions classified on biopsy as superficial or nodular on biopsy, 26% were reclassified as micronodular or invasive on excision. Not good for Aldara on superficial BCCs, if it isn’t truly superficial

  2. #2 by Paul O'Brien on May 10, 2012 - 4:11 am

    I agree with Tony. It is one reason I tend to excise most BCC even if superficial on initial biopsy. I have noticed myself how often the subtype indicates an invasive BCC when the biopsy indicates superficial. Not only is it a problem for Imiquimod but also ablative techniques.

  3. #3 by John Pyne on May 12, 2012 - 8:49 am

    100 random BCC would not contain may micronodular subtypes.

    The dermoscopy of micronodular BCC may be a confounder. They are often pale and may not be as obvious as other subtypes – so presenting later as deeper tumours.

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