Table of Contents
What Are Eruptive Vellus Hair Cysts?
Eruptive vellus hair cysts (EVHC) are an uncommon dermatological condition known. Esterly and Cols originally coined the term "EVHC" in 1977. It is an anomaly in the vellus hair follicular development. The vellus hairs are fine, golden hairs typically occur on the face, upper body, and limbs. Small, dome-shaped, smooth, reddish-brown papules, ranging in diameter from 1 to 4 mm are the most common signs of this condition.
It usually appears on the abdomen, limbs, and chest. It may be autosomal dominant or sporadic and is most frequently observed in children, teenagers, or young adults. The majority of lesions only cause cosmetic concerns and are asymptomatic. It is still unknown what specifically caused the illness.
Histologically, it is characterized by various transversely and obliquely cut vellus hair and cystic gaps lined by stratified squamous epithelium made of varying amounts of laminated keratin. Despite being benign, these cysts can be difficult to diagnose and treat because of their unique appearance and chance of returning.
What Causes Eruptive Vellus Hair Cysts?
Vellus hair follicles, which are tiny, fine hairs found on most body surfaces, are thought to be the origin of eruptive vellus hair cysts. The infundibulum, the portion of the hair follicle directly beneath the epidermis, can get clogged, which causes keratin to build up and eventually create cysts. Although this obstruction's precise etiology is unknown, environmental variables, hormonal effects, and genetic predispositions may all impact how they develop. Keratin gene mutations are likely to be linked with familial instances when they have an autosomal dominant inheritance pattern, which means an abnormal gene originates from a single parent. The gene encoding keratin 17 (K17) has undergone mutations in certain instances.
How Do Eruptive Vellus Hair Cysts Look Like?
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Clinically, eruptive vellus hair cysts (EVHCs) appear as distinct follicular papules. Pimples can have a yellow, bluish-gray, red, or slightly reddish-brown appearance.
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Two types of EVHCs have been documented: face variations and generalized EVHCs.
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Both sexes are equally impacted.
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EVHCs can develop in childhood or be present from birth. Lesions usually appear in the first and second decades, with the advent of puberty in rare situations.
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The most prevalent areas of involvement are the flexor or extensor surfaces of the extremities and the chest. However, they have also been reported on the ear, vulva, and limbs.
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Patients frequently have several hundred cysts, although sometimes they just have a couple.
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Cysts often have a smooth, dome-shaped surface with a 1 to 4 mm diameter. They can sometimes exhibit umbilication, hyperkeratotic crusts, or central puncta.
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Though severe symptoms are uncommon, people may occasionally have moderate itching or soreness underlying the cysts.
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Like perforating folliculitis, mechanical stimulation of the cysts may result in the removal of retained vellus hairs.
What Is the Differential Diagnosis of Eruptive Vellus Hair Cysts?
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Acneiform Eruptions: These comprise comedones and acne vulgaris, which can manifest as EVHC-like papules.
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Folliculitis: It presents as tiny pimples or lumps grouped around hair follicles. It might result in painful, sensitive, burning, or itchy skin.
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Keratosis Pilaris: This benign skin condition typically affects the upper arms, thighs, cheeks, or buttocks and is characterized by dry, rough patches and small bumps.
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Milia: Tiny, superficial cysts filled with keratin frequently seen in adults or neonates.
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Trichilemmal Cysts: Usually found on the scalp, these cysts are thicker in the wall and are also called pilar cysts.
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Tuberous Sclerosis Follicular Papules: These flesh-colored papules have a distinct distribution associated with this hereditary condition.
How Are Eruptive Vellus Hair Cysts Diagnosed?
The distinctive appearance and distribution of the lesions serve as the primary basis for the clinical diagnosis of EVHCs. However, histological analysis is frequently necessary for a conclusive diagnosis, especially in unusual instances or when additional illnesses are suspected. The vellus hairs can be seen by making an incision or puncture in the cyst and using a microscope to examine the contents. A skin biopsy might confirm the diagnosis. Typically, an EVHC's skin biopsy reveals:
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These have vellus hairs and laminated keratinous material, and they are bordered by stratified squamous epithelium.
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One of the characteristics of EVHCs is the presence of many vellus hairs inside the cyst.
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In contrast to other forms of cysts, the cyst wall typically comprises many layers of epithelial cells without a granular layer.
What Is the Treatment for Eruptive Vellus Hair Cysts?
The lesions of eruptive vellus hair cysts are usually harmless, so treatment is not essential in many situations. In roughly 25 % of youngsters, the cysts go away independently. The treatment for eruptive vellus hair cysts may include:
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Watchful Waiting: Parents of a child who presents with multiple tiny cysts on the arms and chest traditionally may be advised to wait patiently, as a considerable portion of patients experience spontaneous resolution.
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Topical Treatments: By increasing epithelial cell turnover and decreasing follicular occlusion, topical retinoids, including Tretinoin, can help prevent the development of new cysts.
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Intralesional Injections: Corticosteroid injections, usually limited to symptomatic instances, can decrease cysts and reduce inflammation.
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Laser Therapy: Cysts can be successfully removed with various laser treatments, including CO2 and erbium lasers. While these techniques are precise and leave little to no scars, they could need several sessions.
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Surgical Excision: Surgical excision is a viable treatment option for solitary or symptomatic cysts. This method is impractical for treating several lesions and may leave scars.
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Oral Retinoids: Oral Isotretinoin may be administered in severe or widespread cases. Although there is a high risk of side effects, this systemic treatment can reduce the frequency of cysts but needs to be closely monitored.
Conclusion
Eruptive vellus hair cysts are uncommon and benign conditions. They are usually asymptomatic; however, their visual appearance can significantly adversely impact a patient's quality of life. As it is a rare condition, diagnosis will be challenging. Histopathological examination plays a vital role in establishing a definite diagnosis. Dermatologists and other healthcare professionals must be comprehensively aware of the illness, including its clinical presentation, diagnostic standards, and available treatments.
