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| CORRESPONDENCE |
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| Year : 2021 | Volume
: 39
| Issue : 4 | Page : 216-217 |
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Demodex folliculitis of the scalp successfully treated with topical ivermectin
Wei-Cheng Fang1, Stephen Chu-Sung Hu2
1 Department of Dermatology, Kaohsiung Medical University Hospital; Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
2 Department of Dermatology, Kaohsiung Medical University Hospital; Department of Dermatology, College of Medicine, Kaohsiung Medical University; Department of Dermatology, Kaohsiung Municipal Siaogang Hospital, Kaohsiung, Taiwan
| Date of Submission | 25-Jul-2021 |
| Date of Decision | 05-Oct-2021 |
| Date of Acceptance | 20-Oct-2021 |
| Date of Web Publication | 29-Dec-2021 |
Correspondence Address:
Dr. Stephen Chu-Sung Hu
Department of Dermatology, Kaohsiung Medical University Hospital, No. 100, Tzyou 1st Road, Kaohsiung 807
Taiwan
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/ds.ds_46_21
How to cite this article:
Fang WC, Hu SC. Demodex folliculitis of the scalp successfully treated with topical ivermectin. Dermatol Sin 2021;39:216-7 |
Dear Editor,
Demodex is a common saprophytic mite which lives in human pilosebaceous units.[1] Although Demodex may be just an innocent bystander in many cases, it has been implicated as a pathogen in various skin diseases, including pityriasis folliculorum, rosacea-like demodicosis, papulopustular rosacea, demodicosis gravis, blepharitis, and perioral dermatitis.[1],[2] Demodex folliculitis of the scalp has been rarely reported previously, and treatment options for this skin condition are not well defined. Here, we present a patient with Demodex folliculitis of the scalp that was successfully treated with topical 1% ivermectin.
A 68-year-old Asian man suffered from severe pruritus of the scalp with treatment-resistant scalp lesions for 2 years. He also complained of poor sleep quality due to pruritus. The patient did not have any systemic diseases, and he had not received any immunosuppressive medications. Oral antihistamines and topical steroids had been prescribed, but the scalp condition showed no improvement. Physical examination of the scalp revealed small round alopecic regions with reddish-brown follicular papules, associated with scalp erythema [Figure 1]a and [Figure 1]c. Dermoscopy showed yellowish papules with peripheral telangiectasia [Figure 1]e. Potassium hydroxide (KOH) preparation obtained using the thumbnail-squeezing method[3] revealed multiple Demodex folliculorum mites [Figure 2]a and [Figure 2]b. There were no symptoms or signs of demodicosis on the patient's face. Skin biopsy of the scalp lesion showed dilated blood vessels in the upper dermis, mild mononuclear and neutrophilic infiltration around hair follicles [Figure 2]c, and several Demodex-like structures in the hair follicles [Figure 2]d. These features were consistent with the diagnosis of Demodex folliculitis. | Figure 1: (a and c) Physical examination of the scalp revealed small round alopecic regions with reddish-brown follicular papules, associated with scalp erythema. (b and d) The scalp lesions resolved after treatment with topical ivermectin. (e) Dermoscopy showed yellowish papules with peripheral telangiectasia. (f) Follow-up dermoscopy after topical ivermectin treatment revealed decreased erythema and telangiectasia.
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 | Figure 2: (a and b) A potassium hydroxide preparation from the scalp lesions revealed multiple Demodex folliculorum mites (indicated by *) (a, ×40; b, ×200). (c and d) Skin biopsy showed dilated blood vessels in the upper dermis, mild mononuclear and neutrophilic infiltration around hair follicles, and several Demodex-like structures in the hair follicles (c, ×100; d, ×200).
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The patient was prescribed various treatments, including oral doxycycline 100 mg twice a day for 1 month, topical 0.75% metronidazole twice a day for 3 weeks, topical 10% crotamiton twice a day for 1 month, and topical 1% gamma-benzene hexachloride once weekly for 1 month. However, the clinical response was poor, and the scalp papules persisted. The treatment regimen was then changed to topical 1% ivermectin, which was applied to the whole scalp once daily for 1 month. The pruritus sensation improved dramatically, and the scalp papules resolved [Figure 1]b and [Figure 1]d. No side effects were noted during topical ivermectin treatment. Follow-up dermoscopy revealed decreased erythema and telangiectasia [Figure 1]f. Repeat KOH examination after topical ivermectin treatment showed no evidence of Demodex mites.
Two species of Demodex, D. folliculorum and D. brevis, are commonly found in humans. D. folliculorum typically lives in the follicular infundibulum, whereas D. brevis resides in the sebaceous glands. Demodex mites are most commonly found in the cheeks, nasolabial folds, nose, and forehead.[4] Previously, very few reports of demodicosis of the scalp have been published. Helou et al. reported that Demodex infestation of the scalp may be associated with a clinical presentation of folliculitis, characterized by hair loss, scalp erythema, scaling, and pustules.[5] Gilaberte et al. described a patient with Demodex infestation who presented with follicular papules and pustules on the scalp, and histopathology demonstrated inflammatory infiltrate around follicles with intrafollicular Demodex mites.[6] Consistent with previous reports, our patient presented clinically with hair loss, follicular papules, and scalp erythema. In this patient, we also demonstrated that KOH examination is a simple, rapid, and noninvasive outpatient procedure that can facilitate the diagnosis of Demodex folliculitis.
Currently, there is no consensus on the treatment for demodicosis-associated skin inflammation. Jacob et al. reported that effective treatment methods for Demodex infestation include topical permethrin, crotamiton, benzyl benzoate, and oral metronidazole, which were based on a systematic review from 1946 to 2019.[7] However, treatment options for Demodex folliculitis of the scalp are currently not well defined [Supplementary Table 1]. The skin lesions in our patient responded poorly to topical metronidazole, crotamiton, and gamma-benzene hexachloride but showed a good clinical response to topical ivermectin. Previously, topical ivermectin has been demonstrated to be an effective treatment modality for Demodex-associated rosacea and has a favorable safety profile.[8] However, to our knowledge, the use of topical ivermectin for patients with scalp Demodex folliculitis has not been previously reported.
In this report, we described the clinical, dermoscopic, and microscopic features of a patient with Demodex folliculitis of the scalp, which was successfully treated with topical ivermectin. Clinicians should be aware of this distinctive clinical condition in patients with treatment-resistant scalp pruritus and folliculitis. A high index of clinical suspicion combined with KOH examination may facilitate the early diagnosis of this skin disorder. In addition, we propose that topical ivermectin may be a safe and efficacious treatment option for Demodex folliculitis.
Declaration of patient consent
The authors certify that they have obtained appropriate patient consent form. In the form, the patient has given his consent for the images and other clinical information to be reported in the journal. The patient understands that his name and initial will not be published and due efforts will be made to conceal the identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
This work was supported by a grant from Kaohsiung Medical University Hospital (KMUH-DK(B)110007-4).
Conflicts of interest
Prof. Stephen Chu-Sung Hu, an editorial board member at Dermatologica Sinica, had no role in the peer review process of or decision to publish this article. Dr. Wei-Cheng Fang declared no conflict of interest in writing this paper.
| Supplementary Material | |  |
| References | | |
| 1. | Baima B, Sticherling M. Demodicidosis revisited. Acta Derm Venereol 2002;82:3-6.  |
| 2. | Chang YS, Huang YC. Role of Demodex mite infestation in rosacea: A systematic review and meta-analysis. J Am Acad Dermatol 2017;77:441-7.e6. |
| 3. | Huang HP, Hsu CK, Lee JY. Thumbnail-squeezing method: An effective method for assessing Demodex density in rosacea. J Eur Acad Dermatol Venereol 2020;34:e343-5. |
| 4. | Elston CA, Elston DM. Demodex mites. Clin Dermatol 2014;32:739-43. |
| 5. | Helou W, Avitan-Hersh E, Bergman R. Demodex folliculitis of the scalp: Clinicopathological study of an uncommon entity. Am J Dermatopathol 2016;38:658-63. |
| 6. | Gilaberte Y, Frias MP, Rezusta A, Vera-Alvarez J. Photodynamic therapy with methyl aminolevulinate for resistant scalp folliculitis secondary to Demodex infestation. J Eur Acad Dermatol Venereol 2009;23:718-9. |
| 7. | Jacob S, VanDaele MA, Brown JN. Treatment of Demodex-associated inflammatory skin conditions: A systematic review. Dermatol Ther 2019;32:e13103. |
| 8. | Cardwell LA, Alinia H, Moradi Tuchayi S, Feldman SR. New developments in the treatment of rosacea - Role of once-daily ivermectin cream. Clin Cosmet Investig Dermatol 2016;9:71-7. |
[Figure 1], [Figure 2]
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