Morphological evidence of periodical exacerbation of hyperkeratosis lenticularis perstans

We present a case of hyperkeratosis lenticularis perstans (Flegel's disease) in a 71-year-old-woman. Apart from all the typical morphological features of the disease, we evidenced mounds of parakeratosis that contained neutrophils, alternating with other strata of the horny layers in which no infiltrate was seen. Such a pattern has been described in association with diseases that show a periodic clinical pattern of presentation with periods of exacerbations and remissions. Our case also showed a lichenoid inflammatory chronic infiltrate with vacuolation of the basal layer and mild spongiosis. Both findings strongly support the hypothesis that the inflammatory infiltrate might play a primary role, and that the hyperkeratosis might be a secondary event.