A rare case of herpes simplex virus 1 folliculitis on the scalp of a military member

Introduction

Herpes simplex virus 1 (HSV-1) folliculitis of the scalp is an exceedingly rare condition that has seldom been documented in medical literature. Folliculitis itself is a prevalent inflammatory condition affecting the hair follicles, which typically manifests as erythematous papules, pustules, vesicles, and plaques, causing discomfort that can range from mild pruritus to significant pain. These lesions vary widely in presentation, depending on the severity of inflammation and the depth of follicular involvement. Although folliculitis commonly impacts areas with dense terminal hairs, such as the beard, scalp, and other densely hair-bearing regions, HSV-1 folliculitis specifically is frequently reported in the beard area, often sparking local inflammation and exacerbated by grooming activities that involve frequent shaving.

This case highlights the potential for HSV-1 folliculitis on the scalp to go underdiagnosed, particularly among military personnel who follow stringent grooming standards that may inadvertently exacerbate the condition. Practices such as aggressive shaving, skintight trimming, and sharing of unsterilized grooming tools can create microtrauma to the scalp, facilitating viral inoculation or spread and subsequently triggering or exacerbating HSV-related folliculitis. Military grooming standards often mandate daily or frequent shaving of both the face and scalp, practices that may inadvertently lead to repeated trauma to the hair follicles, which can weaken the skin's barrier and render it more vulnerable to infections, including HSV-1.

Case report

We report the case of a 54-year-old Caucasian male, retired from the US Army, who presented with a long-standing refractory case of folliculitis decalvans. Prior treatments with multiple topical and oral antibiotics, antifungals, and intralesional steroids did not provide long-term relief or improvement. On physical examination, he exhibited scattered erythematous papules, diffuse scarring, and hair tufting across the vertex and posterior scalp. Initial treatment with isotretinoin 40 mg daily ×1 month and Naftin 1% topical cream led to symptom improvement and fewer new lesions. Due to promising initial results, isotretinoin was increased to 60 mg daily for an additional 2 months; however, the patient developed new inflamed papules on the vertex and posterior scalp with severe pruritus, prompting frequent scratching.

Upon reevaluation, numerous crusted papules (1-4 mm) were observed amid diffuse scarring (Fig 1). Given the recurrence, isotretinoin was discontinued, and a new regimen of minocycline 50 mg twice a day, pimecrolimus (Elidel) 1% cream twice a day, and benzoyl peroxide 5% topical liquid daily was initiated. Bacterial and viral cultures were also obtained, ultimately revealing HSV-1 DNA. The patient began a 10-day course of valacyclovir 1 g twice a day, with discontinuation of all other medications, except benzoyl peroxide. After 10 days, the patient reported improvements in pruritus and the appearance of the lesions (Fig 2), leading to a subsequent 14-day extension of valacyclovir therapy which resolved his condition.

Fig 1.

HSV-1 folliculitis of the scalp—before treatment with valacyclovir 1 g twice a day, demonstrating numerous crusted 1 to 4 mm papules on vertex and posterior scalp, among diffuse scarring. HSV-1, Herpes simplex virus 1.

Fig 2.

HSV-1 folliculitis of the scalp—posttreatment with valacyclovir 1 g twice a day ×10 days. HSV-1, Herpes simplex virus 1.

Discussion

HSV-1 folliculitis of the scalp is a rare form of folliculitis, seldom documented in medical literature, but potentially underdiagnosed, especially in military settings. Miliauskas and Leong reported a case of occipital herpetic folliculitis; though it was concurrent with HSV-associated lymphadenopathy.¹ In addition, HSV-2 has been documented as a cause of herpetic folliculitis on the scalp as reported by Foti et al.² Military regulations mandate frequent skintight trimming of the scalp and daily shaving of facial hair, practices that can trigger or exacerbate folliculitis in addition to wearing military equipment such as gas and oxygen masks.³ Chronic folliculitis in these areas can lead to scarring, creating lasting impacts for the patient, along with persistent pruritic and painful lesions that affect daily life.

Folliculitis is pathologically characterized by neutrophilic infiltration extending into the epithelium and follicular canal, leading to inflammation.^4,5 In cases of folliculitis decalvans, which the patient was initially diagnosed with, inflammation results in chronic cicatricial alopecia, as observed in this patient following unsuccessful treatments with topical and oral antibiotics, antifungals, steroids, and isotretinoin.⁶ Microtrauma, such as from shaving or scratching pruritic areas, is well known to exacerbate and spread folliculitis.⁷ This can be made worse by utilizing unhygienic or uncleansed grooming tools. Herpetic sycosis, a herpes simplex infection of the beard area, is not uncommon among those who shave with a razor blade, which may serve as a vector if used on both the face and scalp. This could explain the spread of herpes simplex from the beard area to the scalp in such cases.

Common treatments for facial or beard folliculitis typically involve medications like topical benzoyl peroxide, steroids, and antibiotics, particularly those with antiinflammatory effects, as inflammation and bacterial infection are common contributors.⁸ However, these initial therapies did not improve symptoms in our patient, prompting treatment with isotretinoin, which only yielded minimal improvement after 1 month and worsened after 2 additional months. Various topical and oral antifungals were also tried, ruling out fungal causes. Ultimately, a culture revealing HSV-1 confirmed the diagnosis, allowing for appropriate antiviral treatment. While herpetic sycosis is documented in men shaving their face with a razor, it has rarely been described on the scalp. In immunosuppressed or patients with HIV, herpes simplex folliculitis may be more widespread, unlike the localized folliculitis observed on this patient's scalp.

Differentiating herpes simplex folliculitis of the scalp from other conditions, such as gram-negative folliculitis, dermatophyte folliculitis, irritant folliculitis, pityrosporum folliculitis, folliculitis decalvans, and demodex folliculitis, is crucial for appropriate treatment and prognosis. Delayed identification and appropriate treatment, as seen in this patient treated for non-HSV causes over many years, may lead to scarring alopecia—a concern with both cosmetic and psychological impacts. Early viral cultures in refractory folliculitis cases can enable timely antiviral intervention, reducing complications. This is especially relevant in the military, where strict grooming practices may exacerbate folliculitis and the spread of potential infections.

Furthermore, this case underscores the importance of proper grooming hygiene to prevent HSV transmission, particularly in environments where tools are commonly shared or not always adequately sterilized. Educational initiatives focused on grooming hygiene and viral etiologies in folliculitis would aid health care providers and patients in recognizing HSV-related folliculitis early. This heightened awareness could improve patient outcomes by allowing for timely effective antiviral treatment and minimizing the chronicity and scarring associated with undiagnosed viral folliculitis.

Conflicts of interest

None disclosed.