Alopecia Following Tick Bites

A recent case report published in JAAD Case Reports has brought renewed attention to alopecia following tick bites, a rare but intriguing condition documented sporadically since the early 1900s. While most previously reported cases have described localized hair loss confined to the site of the tick attachment, this particular case presents a notable departure from that pattern, revealing diffuse alopecia areata-like hair loss in a patient.

Case Report

A 28-year-old woman with well-controlled polycystic ovary syndrome presented with a 7-month history of hair loss after a tick bite on her scalp. Initially, she experienced localized alopecia around the bite site, but within a month, the hair loss spread diffusely across her entire scalp. Previous treatments, including over-the-counter vitamins and intralesional corticosteroids, were ineffective.

Upon examination, she exhibited diffuse patchy hair loss, marked by a Severity of Alopecia Tool score of 52, yellow and black dots, exclamation point hairs, and postinflammatory hyperpigmentation at the bite site. Notably, she retained her eyebrows, eyelashes, and body hair. A 4 mm punch biopsy of the attachment site revealed a predominance of vellus hair follicles, with 42% in catagen/telogen phases, along with mild inflammatory changes.

The patient was started on a prednisone taper, transitioning to baricitinib at 4 mg daily. Improvement was observed within a month, and after four months of treatment, significant regrowth occurred in most alopecic areas, except for the tick attachment site and its immediate vicinity.

Discussion

The researchers note that tick bite alopecia, though rare, typically presents with a scalp eschar at the attachment site, accompanied by surrounding nonscarring or cicatricial alopecia. The attachment of hard ticks can lead to tissue necrosis, forming an eschar that evolves into cicatricial alopecia. Tick saliva triggers an abnormal telogen response through its anticoagulant, anti-inflammatory, and immunomodulatory properties, resulting in hair loss around the bite site. While hair loss patterns can vary, they usually resolve within three months to five years, with the eschar often persisting.

Recent reports have documented atypical hair loss patterns following tick bites, including localized alopecia areata-like changes. The case described highlights a unique diffuse alopecia areata-like response, alongside the traditional features of tick bite alopecia. Biopsy results align with previous findings, showing hair follicle miniaturization, an increased number of catagen and telogen hairs, and perivascular lymphocytic infiltrates.

The distinctive presence of yellow and black dots, exclamation point hairs, and a rapid response to baricitinib suggests a diagnosis of diffuse alopecia areata rather than telogen effluvium.

"Our case provides valuable insight into diverse hair loss patterns following tick bites and underscores the effectiveness of Janus kinase inhibitor therapy, typically used for severe alopecia areata," Shilpa Ghatnekar, Department of Dermatology, Boston University Medical Center, Boston, Massachusetts, and colleagues concluded.

Reference

Ghatnekar S, Seth G, Farah M, Vashi N. Alopecia areata-like hair loss after a tick bite. JAAD Case Rep. 2024 Aug 30;53:34-36. doi: 10.1016/j.jdcr.2024.08.010. PMID: 39430634; PMCID: PMC11488427.