Nevus psiloliparus: report of two nonsyndromic cases.

A diagnosis of nevus psiloliparus was made both clinically and histopathologically in two otherwise healthy girls, one being 4 years and the other one being 1 year old. A congenital hairless patch with a round or oblong shape and a soft surface was noted on the scalp. In one case the lesion was yellowish and flat, whereas in the other case it was skin colored and somewhat elevated. In both cases, histopathological examination showed the absence of mature hair follicles and the presence of undeveloped follicular structures as well as orphaned arrector pili muscles in the dermis. As a new histopathological feature of this type of nevus, we found arrested anlagen of hair bulbs in both cases. The fatty tissue was abundant and also involved, in the form of aberrant lobules, the lower portion of the dermis. Clinical examination did not show any associated extracutaneous abnormality, and during a follow-up period of 2 years in either case, respectively, the children developed without any complication. Although neurological abnormalities could not be excluded by imaging techniques, such extracutaneous involvement is highly unlikely because the nevi psilolipari were of rather limited size. When clinicians and dermatohistopathologists have become familiar with this new entity, they will most likely recognize it as a nonsyndromic skin disorder more often than as a cutaneous sign of encephalocraniocutaneous lipomatosis.