Post-herpetic neuralgia-associated patchy hair loss closely mimicking trichotillomania

Dear Editor,

Trichotillomania (TTM) and alopecia areata are the most common differentials of alopecic patches with definitive borders. Herein, we are sharing a case of patchy hair loss over the scalp and eyebrow caused by constant itching and rubbing over the post-herpetic neuralgia (PHN) affected area, which closely mimicked a TTM alopecic patch.

A 52-year-old female presented to dermatology outpatient services with complaints of frequent itch, burning sensation, and hair loss over the right fronto-temporo-parietal area of the scalp (not crossing the midline) and the right eyebrow for 2 months. On gross examination of the scalp, an alopecic patch with ill-defined borders and broken hairs were visible. Similar findings were appreciable over the right eyebrow [Figures 1 and 2]. Clinical history revealed an acute onset, papulovesicular lesions over the described areas, confined unilaterally, 3 months back that resolved completely within 2 weeks with medications prescribed at the primary health-care center in her vicinity. The onset of papulovesicular lesions was preceded by the sensation of throbbing pain and burning sensation for 2–3 days and was followed by increased lacrimation and burning pain in the right orbital area. During the next few weeks, the itching and burning sensation was severe enough to frequently precipitate the episodes of rubbing and itching. She also developed ptosis in the right eyelid. Facial symmetry was not affected [Figure 1]. She denied a history of any impulsive/conscious hair-pulling episodes and chronic stress conditions (family or personal loss). Further, there were no other signs/symptoms of obsessive-compulsive spectrum disorders such as skin picking disorders (onychophagia, trichophagia onychotillomania, recurrent purpuras or bruises, or skin erosions). Radiography of the abdomen was normal.

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Figure 1:

Alopecic patch with ill-defined borders over the right front-parietal-temporal area, along with diffuse hair loss of the right eyebrow. Associated ptosis can be seen.

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Figure 2:

Superior view of the scalp showing the alopecic patch that developed after the resolution of grouped vesicular lesions.

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Based on the presenting clinical features and close association with a history of preceding pain, burning sensation, followed by papulovesicular lesions respecting the midline and persistent severe itch and burning sensation post-resolution, frictional alopecia secondary to post-PHN in a case of herpes zoster ophthalmicus (HZO) was agreed on as the final diagnosis. Dermoscopic findings of the affected areas further ruled out TTM as classical, and specific features of the TTM, such as perifollicular hemorrhage, flame hairs, hair powder, and “V” hairs, were absent. Findings on dermoscopy (broken hairs, black dots, regrowing hairs, and mild scaling) in our patient are shown in Figure 3. The patient was given once weekly intralesional therapy (Jaipur block), oral medications (pregabalin 75 mg twice a day), and nutritional supplements (methyl-cobalamin). An appreciable improvement in the intensity of pruritus and burning sensation was reported by the patient on the subsequent follow-up visits.

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Figure 3:

Dermoscopic examination showing black dots (black circle), broken hairs (red arrow), bent hairs (red circle), empty follicles (yellow circles), re-growing hairs (green arrow), and scaling (DermLite DL4; ×10:Polarized).

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PHN is the most common complication of herpes zoster, characterized by altered sensations (hypersensitivity, itch, hypoesthesia, and allodynia) or symptoms of autonomic dysfunction (altered sweating).^[1,2] HZO can also lead to ophthalmoplegia (oculomotor nerve palsy being the most common cause), presenting as diplopia, mydriasis, and ptosis. Disruption to the cranial nerve’s supply of levator palpebrae superioris muscle supply can lead to ptosis. It is possible that our patient had some levator palpebrae superioris muscle weakness, as was evident by the ptosis.^[3]

The current case is interesting due to its very close gross resemblance to TTM and frictional alopecia. In doubtful clinical scenarios, dermoscopy can be a useful tool to rule out TTM. Clinically, without a thorough clinical history, these cases can be mistakenly labeled as TTM, which can lead to an unnecessary “pill burden” for the patient, whereas the needed interventions are completely ignored.