Annular atrophic lichen planus and Sneddon's syndrome.

We report the case of a patient who had 2 rare diseases, annular atrophic lichen planus (AALP) and Sneddon's syndrome (SNS). This patient had also digital nodules with histological abnormalities suggestive of SNS vasculopathy, which have not been reported so far. AALP is the most rare of all varieties of lichen planus since this case is the third reported to date. The association of livedo racemosa and cerebrovascular disease is the hallmark of SNS, the incidence of which is estimated to be 4 cases per year per million inhabitants. In both diseases, an abnormal production of elastic-tissue-degrading enzymes or a constitutional abnormality of the elastic tissue can be postulated, since SNS is characterized by arteriolar changes with deterioration of the internal elastic lamina and AALP by destruction of the dermal elastic tissue.