Characteristics of Superficial Basal Cell Carcinomas Containing More Aggressive Subtypes on Final Histopathologic Diagnosis

August 2021 | Volume 20 | Issue 8 | Original Article | 874 | Copyright © August 2021


Published online July 23, 2021

doi:10.36849/JDD.5838

Grace K. Sohn MD,a* Karen Keniston BS,a* Swati Kannan MD,b Brian Hinds MD,a Shang I Brian Jiang MDa

aUniversity of California San Diego, San Diego, CA
bKaiser Permanente, Riverside Medical Center, Riverside, CA

*Co-first authors with equal contributions.

Abstract
Background: The prognosis and treatment of basal cell carcinoma (BCC) are largely dependent on tumor subtype, which is typically determined by punch or shave biopsy. Data regarding concordance between BCC subtype on initial biopsy and final histopathology for Mohs micrographic surgery (MMS) or excision with frozen sections (EFS) are limited.
Objectives: To determine the concordance between initial biopsy and final MMS or EFS subtyping of BCC. We aim to investigate the incidence and clinical characteristics of lesions initially diagnosed as superficial BCC (sBCC) that are later found to have a nodular, micronodular, or infiltrative component.
Methods: We conducted a retrospective review of all MMS or EFS cases performed at a single academic center from August 1, 2015, to August 31, 2017. Inclusion criteria were a biopsy-proven diagnosis of sBCC and presence of residual tumor following stage I of MMS or EFS. Fisher’s exact test was used to evaluate significance of clinical characteristics and outcomes associated with the presence of a nodular, micronodular, or infiltrative BCC component.
Results: A total of 164 MMS or EFS cases had an initial biopsy showing sBCC. Of these, 117 had residual BCC on stage I, and 43 (37%) were found to have a nodular, micronodular, or infiltrative component. Significant predictors of reclassified BCC subtype included age over 60 years (P= 0.006) and location on the head or neck (P=0.043). Reclassified lesions required significantly more stages of MMS to clear (P=0.036). Shave biopsy was used to diagnose 114 (97%) of the included cases.
Conclusions: Over one third of shave biopsies that initially diagnosed sBCC failed to detect a nodular, micronodular, or infiltrative component. Management of biopsy-proven sBCC should take into account the possible presence of an undiagnosed deeper tumor component with appropriate margin-assessment treatment modalities when clinically indicated.

J Drugs Dermatol. 2021;20(8):874-879. doi:10.36849/JDD.5838

INTRODUCTION

Initial diagnosis of basal cell carcinoma (BCC) and its histopathologic subtype is typically made by punch or shave biopsy.1–4 Prior studies have shown that the agreement between BCC subtype in the initial biopsy specimen and subsequent excision specimen to be only 60.9% to 72.3%.5–8 Accurate pre-operative diagnosis of BCC subtype is important for the dermatologist’s clinical management as treatment options differ depending on subtype.

The treatment of choice for most BCC subtypes, including nodular, micronodular, and infiltrative, is standard excision or Mohs micrographic surgery (MMS).9–11 However, there remains debate regarding the most appropriate treatment for superficial BCC (sBCC). Some authors claim that sBCCs represent indolent, low-risk tumors that may be inappropriate for MMS,12 while others argue that a significant number of sBCCs contain concurrent, more aggressive tumor subtypes undiagnosed on initial biopsy that warrant MMS.13,14

In an effort to shed further light on this debate and better characterize the accuracy of a diagnosis of sBCC on initial biopsy, this study aims to determine the concordance between the initial biopsy and final MMS or excision with frozen sections (EFS) subtyping of BCC. Specifically, we strive to investigate the incidence and clinical characteristics of lesions initially diagnosed as sBCC that are later found to have an additional nodular, micronodular, or infiltrative tumor component.
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