Unilateral Widespread Lichen Planus Following Blaschko's Lines After Mycoplasma Pneumoniae Infection

In a case study from 2013, an 8-year-old girl developed unilateral widespread lichen planus (LP) following a Mycoplasma pneumoniae infection (MPI). The LP presented as small dome-shaped papules distributed in a linear or zosteriform pattern along Blaschko's lines on the left side of her body. Despite high Mycoplasma antibody titers, tests for drug causality were negative, suggesting that the LP was not drug-induced. Histopathological examination revealed a band-like lymphocytic infiltrate at the dermoepidermal junction and mixed infiltration of CD4+ and CD8+ T cells. The LP was treated with tacrolimus ointment and improved. This case is notable for the rare presentation of unilateral LP following Blaschko's lines after MPI, suggesting an immunological reaction to the infection may have triggered the LP.