The co-existence of an infiltrative basal cell carcinoma (iBCC) and a desmoplastic trichoepithelioma (DTE) within the same cutaneous lesion is a rare occurrence. iBCCs are relatively common malignant skin neoplasms that pose a risk for local tissue destruction and recurrence. DTEs are cutaneous neoplasms originating from hair follicles that may clinically and histologically appear similar to iBCCs but are ultimately benign. Distinguishing between these two entities is important given their differing destructive potential. Herein, we describe the case of a 36-year-old female with a single skin lesion on her left cheek that was comprised of both an iBCC distinct from a DTE, as verified by histopathologic analysis. A literature review highlights the rarity of such collision tumors and discusses the potential genetic links between these two histologically similar cutaneous neoplasms.

Basal cell carcinoma (BCC) remains the most common malignancy worldwide. BCC pathogenesis is a result of the interplay between one\'s environment, genetics, and phenotypic factors. BCC has a low mortality but given its increasing incidence and potential to cause local destruction thus resulting in significant morbidity, it is vital for dermatologists to remain up to date with recent updates in this malignancy\'s pathogenesis and treatment. This article provides a comprehensive review of the pathogenesis of BCC as well as the current treatments available and clinical trials underway. We also touch upon the updated National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology in respect to BCC\'s recommended treatment modalities.