Superficial Basal Cell Cancers Demonstrate Higher Rates of Mixed Histology on High-Risk Anatomical Sites.

BACKGROUND The Mohs Appropriate Use Criteria (MAUC) have come into question recently regarding the most appropriate treatment for superficial basal cell carcinoma (sBCC). At the heart of this debate is the limited body of evidence describing tumor behavior of sBCC based on clinical factors relevant to the MAUC. OBJECTIVE To determine whether sBCC is more likely to harbor aggressive subtypes in high-risk anatomical locations and in immunocompromised patients. MATERIALS AND METHODS A single institution retrospective review produced 133 evaluable Mohs cases performed on sBCC over a 10-year period. All slides from the respective cases were reviewed for the presence of histologic patterns other than known sBCC. Cases were then grouped by both MAUC anatomical zone (H, M, and L) and patient immune status for statistical analysis. RESULTS A significantly higher rate of mixed histology (MH) was observed when comparing Zone H with Zone L across all patients, healthy patients, and immunocompromised patients. The same was true when comparing Zone M with Zone L for all patients and healthy patients (immunocompromised did not reach significance). CONCLUSION The authors' data very clearly demonstrate a higher rate of MH in sBCC of the head and neck which provides strong support to the current MAUC scoring.