|LETTERS TO EDITOR
|Year : 2016 | Volume
| Issue : 1 | Page : 76-78
Eruptive vellus hair cyst
K Haritha, Anchala Parthasaradhi, Jigisha Jalu
Anchala's Skin Institute and Research Centre, Hyderabad, Telangana, India
|Date of Web Publication||4-Jan-2016|
Anchala's Skin Institute and Research Centre, Near Apollo Bus Stop, Jubilee Hills, Hyderabad - 500 033, Telangana
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Haritha K, Parthasaradhi A, Jalu J. Eruptive vellus hair cyst. Indian J Paediatr Dermatol 2016;17:76-8
Eruptive vellus hair cyst (EVHC) is a follicular disorder presenting as asymptomatic, papular lesions. Commonly affected sites are chest and extremities where they appear as reddish-brown papules. EVHCs are quite rare and underreported. We report a case of a male child who presented with asymptomatic papules on the chest.
A 4-year-old boy presented with multiple, asymptomatic, skin colored to dark, and raised solid skin lesions over chest since 8 months. The lesions were gradually increasing in number. There was no history of any discharge, prior application of any medicine or massage. Cutaneous examination showed multiple, polysized (1–4 mm), skin colored to hyperpigmented, discrete, and nontender papules over the anterior aspect of chest extending to axillary region [Figure 1]. Mucosa, hair and nail examination was normal. General physical examination was normal.
|Figure 1: Multiple, polysized skin colored to dark papules over chest extending to axilla|
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Differential diagnosis of milia, steatocystoma multiplex, EVHC, folliculitis, and keratosis pilaris were kept, and a biopsy was taken from a papule. All routine investigations were normal. Histopathology showed a cyst in the dermis containing multiple, small vellus hair shafts along with the laminated keratinous material. Surrounding the cyst, an inflammatory reaction was seen containing histiocytes and lymphocytes [Figure 2].
|Figure 2: High power view (×40) showing cyst with laminated keratinous material and small vellus hair shafts depicted by arrow|
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Based on histopathology the final diagnosis of EVHC was made. He was kept on topical retinoid (tretinoin 0.1%) cream.
EVHCs are asymptomatic, monomorphic, and follicular lesions described by Esterly et al. in 1977 for the first time. The usual age of onset is between 17 and 24 years, but they can occur at any age, and they may be congenital. They affect both genders equally, and there is no ethical or racial difference. They can be inherited as an autosomal dominant disorder. The exact pathogenesis is not known; some authors consider them to be a developmental abnormality of vellus hair , and some propose they are hamartoma of the pilosebaceous unit. EVHC can be localized or generalized, presenting as discrete monomorphic follicular papules and can sometimes be hyperkeratotic or umbilicated. Usually asymptomatic but there are cases reports of them being associated with pain  or pruritus. Commonly they affect chest and extremities, there are, however, case reports of other site involvement such as face, neck, and abdomen.
Histopathologically the cyst is located in the mid dermis and is lined by squamous epithelium. It contains laminated keratinous material and varying numbers of obliquely cut vellus hairs. They resemble steatocystoma multiplex and infundibular cysts histologically. They all affect anterior chest wall commonly, however, the latter two do not contain vellus hair. The cysts of steat
ocystoma multiplex arise in the sebaceous duct and have a crenulated, eosinophilic, and hyaline lining. Steatocystomas also contain sebaceous glands arising within the cyst wall. Recently, cytokeratin staining has helped in differentiation between all these lesions. Expression of K17 with the concomitant absence of K10 promises to be a diagnostic feature of EVHC and thus differentiating it from other epidermal cysts. Confirmative diagnosis is by biopsy and noninvasively by potassium hydroxide mount of cystic content, which shows vellus hairs.
It is essentially a nonbothersome disease, and 25% shows spontaneous resolution. Treatment options include using topical keratolytic agents such as topical retinoids, 10% urea, 12% lactic acid, as well as topical calcipotriol and laser ablation using CO2 or erbium-YAG laser. Laser treatment should be used cautiously as there are reports of resulting scarring. Other modalities are dermabrasion, surgical incision and drainage, and needle evacuation using an 18-guage needle. In our case, the patient was treated with 0.1% tretinoin cream as his parents did not consent to invasive treatments.
Asymptomatic skin colored to dark papules over the chest can always be mistaken for milia, lichen nitidus, comedonal acne, keratosis pilaris, steatocystoma multiplex, syringomas, comedones, keratosis pilaris, perforating folliculitis, and molluscum contagiosum. Henceforth, a diagnosis of EVHC should be thought of when differentiating the above conditions and histopathology will help us to establish the correct diagnosis.
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[Figure 1], [Figure 2]