Markedly Exophytic Hypertrophic Lichen Planus in a Patient With Ichthyosis Vulgaris

Hypertrophic lichen planus (HLP) is an idiopathic inflammatory condition characterized by hyperkeratotic plaques or nodules, typically occurring bilaterally on the wrists, ankles, or lower extremities. This variant of lichen planus is more common among African-American patients and occupies a broad differential with other keratotic skin conditions, some of which are malignant, making recognition and accurate diagnosis essential. We present an unusual case of a 49-year-old African-American woman with four markedly exophytic, horn-like lesions on her shins, ultimately diagnosed as HLP. Her medical history was also notable for ichthyosis vulgaris. Although no known interaction exists between HLP and ichthyosis vulgaris, the combination of these conditions may have contributed to intense pruritus, leading to increased excoriation. This excoriation could have influenced the unusual growth pattern, as mechanical disruption is associated with increased keratin production in hyperkeratotic conditions.