Squamous Cell Carcinoma Invasive Features

• Unlike SCCIS and AKs squamous cell carcinomas tend not to have a distinct or prominent DEJ

• The focus of the epidermal thickening is from the Stratum Spinosum layer of the epidermis

• The thickened Stratum Spinosum tends to appear more hyporeflective than normal epidermal keratinocytes owing to the frequency of dysplastic cells

• Invasion of atypical squamous epidermal keratinocytes through the basal membrane into the dermis layers

• Migration of the granular cell texture into the mottled collagen

• Complete absence of the DEJ in the area of invasion

• Loss of mottled collagen texture and increased hyporeflectivity due to squamous cells

• Formation of distinct hyperkeratotic plaques of varying thickness are common in invasive SCCs

• Invasion causing distinct loss of collagen texture and adnexal structures even when partially obscured by shadows cast from overlying keratin plaques