Trichilemmal cyst nevus: a new complex organoid epidermal nevus.

A 31-year-old woman had an organoid nevus characterized by multiple trichilemmal cysts arranged in a bandlike pattern. The involved streaks followed Blaschko's lines and were covered, in addition, by multiple filiform hyperkeratoses and comedo-like plugs. Some histopathologic features of this complex nevus were reminiscent of those of well-established organoid nevi such as nevus comedonicus, porokeratotic eccrine nevus, or hair follicle nevus, but the presence of multiple large trichilemmal cysts was a conspicuously distinctive abnormality. Consequently, we propose for this new organoid nevus the names "trichilemmal cyst nevus" or "nevus trichilemmocysticus."