hyperplastic actinic keratosis

In the hyperplastic (hypertrophic) form there is prominent orthokeratosis with alternating parakeratosis.

The epidermis usually shows irregular psoriasiform hyperplasia, and sometimes there is mild papillomatosis.

Dysplastic changes are sometimes minimal and confined to the basal layer.

The presence of vertical collagen bundles and some dilated vessels in the papillary dermis is evidence that these lesions represent actinic keratoses, with superimposed changes due to rubbing or scratching (lichen simplex chronicus).

Hyperplastic (hypertrophic) forms have a higher resistance to apoptotic stimuli compared to atrophic variants.

See also

 actinic keratosis