An immunopathological study of lichen planus

Twenty-five patients with clinically diagnosed lichen planus were examined for direct immunofluorescence patterns in biopsies. The male to female ratio was 1:1.77. The peak incidence was observed in 11-20 years age group. Most (96%) of the patients presented with moderate to severe itching within two months of onset of symptoms. Sixty percent of the patients had violaceous papules; 20% had both papules and plaques. Simultaneous oral involvement was seen in 4% of cases; 8% showed nail changes. Thirteen patients had classical LP, 9 had lichen planus hypertrophicus, 2 had lichen planus actinicus, and one had lichen planopilaris. Direct immunofluorescence revealed fibrin deposition in 64% of cases as a linear pattern at dermo-epidermal junction, as coarse granular deposits of IgM sub-epidermally in 24 of cases and at the dermo-epidermal junction as C 3 in20% of cases. Civatte bodies were seen in 5 cases with H&E staining, but direct immunofluorescence for IgM, fibrin and C 3 was observed only in two cases. This suggests activation of complement and fibrinogen cascade. Whether this is the cause or effect of pathological processes in lichen planus remains to be determined.