Background: Annular lichen planus (ALP) is a long-recognized clinical variant of lichen planus, but is often considered uncommon in occurrence. The typical distribution and presentation of this variant have not been well described.
Objective: We sought to better define the sites affected and clinical characteristics of the annular variant of lichen planus, along with the age and race of patients affected with this disorder.
Methods: We conducted a retrospective review of 20 patients given a diagnosis of ALP during an 18-year period. The diagnosis was confirmed histologically in all but 3 cases of classic ALP that presented on the glans penis.
Results: Patients ranged in age from 24 to 76 years. There were 18 men and 2 women; 15 were Caucasian and 5 were African American. Sites of involvement in order of decreasing frequency included: axilla (35%); penis (25%); extremities (25%); groin (including the inguinal creases and scrotum) (20%); back (15%); buttocks (10%); flanks (5%); neck (5%); and eyelids (5%). None of the patients had oral mucosal, vulval, scalp, or nail lesions. A total of 18 patients had purely annular lesions, whereas 2 of the 20 had a few purple polygonal papules in the vicinity of the annular forms. Some eruptions were macular, whereas the majority had a slightly raised edge with central clearing. In all, 6 patients had solitary lesions whereas only 4 had 10 or greater lesions. None exhibited a linear Koebnerized response or generalized lesions. Most patients were asymptomatic.
Conclusions: ALP commonly involves the male genitalia but also has a predilection for intertriginous areas such as the axilla and groin folds. Eruptions typically consist of a few lesions localized to one or a few sites. Distal aspects of the extremities, and less commonly the trunk, may also be involved. ALP is a subtype of lichen planus that may be more common than is reflected in the literature.