Just to add to the explanation here is what you would see in the others (most on FA2020 p484)

• Basal cell carcinoma:
• "Palisading" nuclei as well as nests of neoplastic basal cells.
• Typically presents as a pearly, indurated nodule but can be a scaling plaque


• Keratoacanthoma:
• Resembles squamous cell carcinoma in that it is a rapidly growing dome shaped nodule with a keratin filled center
• On histology it basically presents as a crater filled with keratin


• Malignant melanoma:
• Bad boi, look for the ABCDEs (asymmetry, border irregularity, color variation, diameter >6mm, and evolution)
• On histology you see melanocyte proliferation below the basement membrane and it just looks uglier


• Merkel cell carcinoma:
• Rare and typically appears as flesh colored or bluish nodule

What you can see is

1.Hyperkeratosis (thickened stratum corneum) 2.Parakeratosis (you can see the nuclei very clearly in the stratum corneum) 3.Dysplasia (notice keratinocytes hyperchromatic and large nuclei go up almost all the way to the top. This isnt so in normal skin)

all this fits actinic keratosis