Lichenoid tissue reaction in porphyria cutanea tarda

We report a patient presenting with lichenoid plaques on exposed skin who h ad the metabolic features of porphyria cutanea tarda (PCT). Histology of le sional skin demonstrated a lichenoid inflammatory cell infiltrate in the up per dermis, while direct immunofluorescence revealed immunoreactive colloid bodies. Monochromator irradiation testing demonstrated photosensitivity in the visible spectrum consistent with porphyria. Solar-simulated irradiatio n induced a papular reaction with lichenoid histological changes. We propos e that this atypical presentation of PCT may reflect a lichenoid tissue res ponse to a porphyrin-mediated photochemical reaction.