Cutaneous Squamous Cell Carcinoma.

Cutaneous squamous cell carcinoma (cSCC) is a malignant neoplasm of the skin characterized by an aberrant proliferation of keratinocytes. Cutaneous SCC is the second most common malignancy globally, and usually arises in the chronically sun-damaged skin of elderly white individuals. From a pathologist's perspective, it is important to differentiate cSCC from the benign and reactive squamoproliferative lesions and identify the high-risk features associated with aggressive tumor behavior. In this article, we provide an up-to-date overview of cSCC along with its precursor lesions and important histologic variants, with a particular emphasis on the histopathologic features and molecular pathogenesis.