Lichen planopilaris-like changes arising within an epidermal nevus: does this case suggest clues to the etiology of lichen planopilaris?
BACKGROUND
Lichen planopilaris shows a perifollicular lymphocytic infiltrate at the level of infundibulum and the isthmus of the hair bulge resulting in necrotic changes within keratinocytes and eventually hair loss.


OBJECTIVE
We present a 14-year-old black male with a history of a raised epidermal lesion on the scalp that was present at birth. Over the past few years, the patient developed gradual hair loss and increased verrucous changes of the skin within the original lesion. Histologic sections of the area showed features consistent with an epidermal nevus peripherally, with a central area showing some features characteristic of those seen in lichen planopilaris. In addition, there was marked hyperkeratosis with increased yeast and bacteria within the follicles.


CONCLUSIONS
Initiating factors in lichen planopilaris are not well defined. Overgrowth of microorganisms with hyperkeratosis results in factors that disrupt the immune privilege of the hair follicle, leading to an immunologic reaction that is limited to the follicle and spares surrounding eccrine structures. This case suggests possible mechanisms involved in the induction of lichen planopilaris.
Smith
K J
KJ
National Naval Medical Center, Bethesda, MD 20889-5600, USA.
Crittenden
J
J
Skelton
H
H
D000293:Adolescent; D000505:Alopecia / Q000209:etiology; D006801:Humans; D008010:Lichen Planus / Q000209:etiology / Q000473:pathology*; D008297:Male; D018330:Nevus, Intradermal / Q000473:pathology*; D012535:Scalp / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology*