Tick Bite Alopecia: A Report and Review.

Tick bites can cause a number of local inflammatory reactions, which are often difficult to differentiate from those induced by other arthropod bites or stings. These include erythematous nodular or pustular lesions, erosive plaques, annular lesions of erythema chronicum migrans, and both scarring and nonscarring inflammatory alopecia. We report a case of nonscarring alopecia in a 21-year-old male who reported a recent history of tick bite to the scalp. The biopsy demonstrated a dense pseudolymphomatous inflammatory infiltrate with numerous eosinophils associated with hair follicle miniaturization and an elevated catagen-telogen count. Signs of external rubbing, including lichen simplex chronicus and the "hamburger sign", were also visualized and are indicative of the associated pruritus. To the authors' knowledge, this is the fifth report of nonscarring tick bite alopecia in the literature and the first in an adult patient. This text will review the classic clinical presentation, histologic findings, and proposed mechanism of tick bite alopecia.