The intertriginous findings, along with results from a punch biopsy showing resolving lichenoid inflammation with post-inflammatory pigmentary alteration, indicated a diagnosis of lichen planus pigmentosus inversus (LPPI).
Insidious onset of usually asymptomatic, sometimes mildly pruritic, well-defined, hyperpigmented macules and patches with occasional Wickham striae of the intertriginous areas is characteristic of LPPI. It is a variant of lichen planus pigmentosus, which conversely occurs on sun-exposed areas. The etiology is unknown and there is no association with medications or sun exposure. Pathophysiology is thought to be chronic inflammation, mediated by T-lymphocyte cytotoxic activity against basal keratinocytes.1
At the time of this patient’s clinical presentation, the differential diagnoses for new onset hyperpigmentation included confluent and reticulated papillomatosis, post-inflammatory hyperpigmentation, and erythema dyschromicum perstans. However, further tests were ordered for diagnostic clarification.
The clinical course of LPPI is variable. In some cases, there is complete resolution of lesions without treatment, while in other cases, lesions may last for years despite treatment and the condition may recur. Current management options include topical calcineurin inhibitors (tacrolimus and pimecrolimus) and topical steroids. Response to these topical medications may be variable. The patient in this case was started on topical tacrolimus 0.1% twice daily, with follow-up in 3 months.
Text courtesy of Rachel Rose, BS, and Daniel Stulberg, MD, FAAFP, Department of Family and Community Medicine, University of New Mexico School of Medicine, Albuquerque. Photo courtesy of Daniel Stulberg, MD, FAAFP.