Porokeratosis
Early
| Superficial perivascular infiltrate of lymphocytes |
| Lichenoid infiltrate of lymphocytes in foci beneath columns of parakeratosis positioned at either end of the lesion |
| Columns of parakeratosis bending inward at the periphery of the lesion; hypogranulosis immediately beneath each column, and dyskeratotic cells and vacuolated cells in the spinous zone |
Fully developed
| Lichenoid infiltrates of lymphocytes across the front of the lesion, i.e., between poles formed by columns of parakeratosis |
| Wiry bundles of collagen in haphazard array accompanying lichenoid infiltrates of lymphocytes |
| Telangiectases and melanophages present often in the zone of altered bundles of collagen |
| Thinned and compactly orthokeratotic epidermis between columns of parakeratosis at the periphery of the lesion |
Late
| All the findings in a fully developed lesion, except inflammatory cells, which are absent |