Actinic Keratosis Histology

Histology or biopsy is rarely needed to make the diagnosis of an actinic keratosis. When lesions are thick or hypertrophic, the physician may perform a biopsy to ensure the lesion has not progressed into an invasive squamous cell carcinoma. The histologic hallmark of an actinic keratosis is keratinocyte atypia of the lower epidermis. By definition, there is no invasion into the dermis in an actinic keratosis.