Nonmelanoma skin cancer (NMSC) is the most common form of cancer in the Caucasian population, with squamous cell carcinoma (SCC) accounting for the majority of NMSC-related metastases and death. While most SCC lesions are indolent tumors with low malignant potential, a wide diversity of SCC subtypes exist, several of which are associated with markedly more aggressive behaviors. Distinguishing these high-risk variants from their counterparts is possible through microscopic analysis, since each subtype possesses unique histopathological features. Early identification of high-risk lesions can allow for more rapid therapeutic intervention, reducing the likelihood of metastasis and death. The authors review specific histopathological features and associated clinical outcomes of the primary subdivisions of SCC.