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

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 (98%) 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(3):283-288. doi:10.36849/JDD.5383.