Lichen Planus Pigmentosus Inversus: Two Case Reports

Introduction: Lichen planus pigmentosus inversus (LPPI) is a rare a rare variant of lichen planus characterized by hyperpigmented patches with predominating localization in intertriginous areas. Due to its rarity, only a few LPPI cases are reported. We herein describe two rare cases of LPPI. Case presentation: The two patients were all with a brownish macular lesion on the intertriginous area. A diagnosis of LPPI was made based on their clinical manifestations, dermoscopic features, and histopathologic features, which revealed an interface change, lichenoid infiltration, and pigmentary incontinence. Discussion: LPPI is pruritic or asymptomatic, hyperpigmented macules and patches on the flexural folds. The axillae and flanks were the most commonly affected areas, followed by the groin and genitalia. About half of the female patients had inframammary fold lesions. LPPI shows higher female predominance than Lichen planus pigmentosus. There were fewer cases that lasted more than 3 years compared to LPP. Conclusion: LPPI is a rare variant of lichen planus, with a locational characteristic and female predominance. Therefore, in the case of a pigmented disease occurring in the flexural folds, it should be placed in the differential diagnosis.