PracticeUpdate Dermatology February 2019

EXPERT OPINION 24

Dermatopathology Reports About Basal Cell Carcinoma Margins Cannot Be Marginal By Warren R. Heymann MD

Dr. Heymann is Professor of Medicine and Pediatrics and Head of the Division of Dermatology at Cooper Medical School of Rowan University, and Clinical Professor of Dermatology at Perelman School of Medicine at the University of Pennsylvania in Philadelphia, Pennsylvania.

“The tumor appears to be completely excised on the sections studied.” I have written that comment thousands of times on my dermatopathology reports for biopsies of basal cell carcinomas (BCCs). When I read the article by Willard- son et al regarding the predictive value of negative margins of BCCs, 1 I gave pause. Do the clinicians understand what I mean by the qualifier “on the sections studied”? It is self-evident (to me) that skin biopsies only reveal up to 2% of a specimen, and, unless marginal assessment akin to the Mohs technique is performed, clinicians cannot be confident that a lesion has been excised. (Even Mohs surgery is not perfect.) What I mean by “on the sections studied” is predicated on the knowledge that, since so little of the specimen is being evaluated, I cannot be sure about the margins if other sections were obtained. What concerned me is that perhaps my comment is being misinterpreted as the lesion is definitely excised and that no further treatment is necessary.

they perform deeper sections if margin assessment is requested by the clinician. BCCs occur in an estimated 2 million Amer- icans annually. The lifetime risk in the US is estimated to be at least 20% and greater than 30% for Caucasians; this could be higher since these estimates are based on data from almost 20 years ago. The BCC cost burden continues to increase with ris- ing incidence. 3 No clinician wants to leave residual tumor behind, and 25% is a significant number. Alternatively, approximately 75% of BCCs were cleared by the biopsy alone. Peri- odically, I will simultaneously perform a shave biopsy immediately followed by destruction (usually electrodesiccation and curettage), especially for small lesions on elderly patients so they need not make a follow-up visit. Of course, reimbursement will only be for the biopsy (unless you wait for the report, and just charge for destruc- tion, if positive). Under such circumstances, whether or not the lesion goes to the mar- gin is moot. If that approach was taken in the majority of cases, imagine the cost sav- ings. (A busy clinician would not be losing very much – instead of scheduling a fol- low-up for local destruction, another patient will be seen instead). Clinicians are least satisfied with pathology laboratories that have poor communication of significantly abnormal results. 4 I will call the clinician directly when there is a potentially urgent diagnosis – melanoma, cutaneous metastasis, etc – but not for a superficial BCCextending to themargin. Regardless, we have to avoid the Cool Hand Luke scenario

150-μm intervals until exhausted. They col- lected 143 cases that met criteria; 34 (24%) were found to contain residual BCC in the corresponding excision, leading to an NPV of 76%; in 31 of 34 (91%) of these cases, the residual histologic subtype was super- ficial. The authors concluded that negative margins in a BCC biopsy are a poor predic- tor of residual disease in the patient. They recommended that clinicians treat these lesions and that pathologists who comment on margin status of BCC biopsies consider adding a caveat to reflect these findings, noting that judgment of definitive treatment should not be based solely on the biopsy. Similar findings were observed in the study of Schnelbelen et al. 2 They collected shave biopsies of squamous cell carcinomas (SCCs) and BCCs that appeared to have uninvolved margins on routine sign-out. They then obtained deeper levels on corresponding tissue blocks until blocks were exhausted and examined them for tumor at biopsy margins. In all, 47 consecutive caseswere collected, including 20 SCCs (43%) and 27 BCCs (57%). Of the 47 cases, 11 (23%) with negative margins at initial diagnosis demonstrated positive margins upon deeper-level examination. Margins of 8 of 27 BCCs and 3 of 20 SCCs were erroneously classified as “negative” on routine examination. The authors do not advocate for the exhaustion of all paraffin tissue blocks on shave biopsies of cutaneous carcinomas because “that exercise would be impractical.” The authors no longer report margin status routinely. For small tumors on which shave biopsies are performed, with curative intent,

Certainly, there is no question that, when a comment is rendered stating “the lesion extends to the margins of the specimen,” more work needs to be done. Additionally, there is no quandary about reporting mar- gins when the lesion has been submitted as an excision of a basal cell carcinoma (by standard excision, shave excision, or saucerization). Willardson et al collected BCC biopsies with negative margin readings that had subsequent excisions to determine the negative predictive value (NPV). 1 For exci- sions read as negative for residual BCC, the excision blocks were sectioned at

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