Jason Emer, MD; Michael Pan, BA; Sebastian Bernardo, BA; Harleen Sidhu, MD
Dr. Emer, Mr. Pan, and Mr. Bernardo are from Mount Sinai School of Medicine, Department of Dermatology, New York, New York. Dr. Sidhu is from Mount Sinai School of Medicine, Department of Pathology, New York, New York.
J Clin Aesthet Dermatol. 2013;6(4):43–45
A healthy eight-year-old boy with no significant past medical history presented to the outpatient dermatology clinic with a new onset, itchy rash on the trunk that started as small, soft, red bumps that quickly hardened. He reported no personal or family history of skin disease and had received no prior treatments for this condition. Physical examination revealed discrete, monomorphic, firm, flesh-colored to hyperpigmented papules on the trunk (Figure 1). Some papules were translucent with a bluish-hue (Figure 2). Punch biopsy was performed for histopathological analysis (Figure 3 and Figure 4).
Eruptive vellus hair cysts (EVHC)
Microscopic Findings and Clinical Course
Punch biopsy performed on the trunk revealed a cyst lined with stratified squamous epithelium and containing keratin (Figure 3 and Figure 4). Upon closer examination, multiple, small vellus hairs were noted within the cyst lumen (Figure 5). The histopathology was consistent with EVHC. Treatment with #11 blade incision and forceps extraction improved the clinical appearance of most lesions and caused resolution of symptoms.
EVHC are benign, relatively uncommon, cutaneous lesions associated with abnormal vellus hair follicles. EVHC were first described in 1977 in a case report of two children suffering from a persistent, asymptomatic, noninfectious rash of small hyperpigmented papules over the surfaces of the forearms, chest, and legs. Histological examination in these patients featured small cysts in the middle dermis containing keratinous material and vellus hairs. Despite more than 30 years since its description, the cause of EVHC continues to remain unknown. An autosomal dominant pattern of inheritance has been suggested in cases of early disease onset among family members. While this condition can occur at any age, most cases are acquired during the first three decades of life with no predilection for a specific sex or racial demographic. Although a small percentage of patients can experience a slow spontaneous remission, there is no cure for this chronic condition, making EVHC particularly difficult to treat.
EVHC presents clinically as small (1–7mm) monomorphic, dome-shaped, pigmented papules. Although single lesions have been reported, numerous papules are typically present. Its distribution can be grouped or scattered and affect any cutaneous surface, including the face, chest, neck, and extremities. Papules can be normal in color or hyperpigmented, soft or firm in consistency, and be translucent with a bluish-hue in appearance. The lesional surface is most often smooth, but may also be crusted and/or umbilicated.[2,3] Although most patients are asymptomatic, rare cases of pruritic and painful lesions have been reported.[4,5]
Heterogeneity in its clinical presentation and gross similarity with other acneiform-like conditions make histopathology the means of establishing a definitive diagnosis. EVHC are located in the middle and/or upper dermis, arising from the follicular infundibulum, and encapsulated by a stratified squamous epithelium 2 to 5 cells thick with an attenuated granular layer. Cross sections of the cystic cavity characteristically show vellus hairs with layered keratinaceous material. The cyst wall is usually devoid of sebaceous glands and may contain melanocytes and Langerhans cells. A granulomatous pattern may appear if the cyst wall is ruptured.
The differential diagnoses of EVHC include steatocystoma multiplex (SCM), milia, comedones, keratosis pilaris, molluscum contagiosum, and acneiform eruptions. EVHC characteristically contain vellus hairs in a cystic cavity. Although SCM may appear histologically similar, a distinguishing histological feature is the presence of sebaceous glands in the cyst wall, which are absent in EVHC. Some patients have “hybrid cysts,” with histological features characteristic of both EVHC and SCM. Due to clinical and histological overlap, some investigators propose that EVHC, SCM, and epidermoid cysts are variants of a single disorder of the pilosebaceous duct.
Currently, there is no standard treatment for EVHC and treatment options are limited. Some patients may experience a gradual remission and all that is needed is the “tincture of time.” If EVHC follows a chronic course or is symptomatic, improvement may be seen with keratolytics, such as tretinoin, tazarotene, lactic or salicylic acid, and/or urea creams. A recent report using topical calcipotriene showed a partial response in a pediatric case. Topical chemical peels with salicylic acid or Jessner’s peels with or without microdermabrasion may be of benefit. Intralesional steroid injection can be attempted at low concentrations (2.5–5mg/cc) largely to treat symptomatic lesions by providing an anti-inflammatory effect. Extraction with an 18-gauge needle or #11 blade with extrusion of the cyst contents can remove lesions without risk of scarring. Simple excision with a punch biopsy will remove the cyst, but with a risk of scarring especially in situations with too numerous and widespread lesion count. Laser therapy with erbium:yttrium-aluminum-garnet (Er:YAG) or carbon dioxide (CO2) may be effective in the reduction of both the number and size of cysts.[12,13] However, adverse effects, such as dyspigmentation and scarring, are a possibility. Laser hair removal with the diode (800–810nm) or neodymium-doped YAG (Nd:YAG), which has proven to have some benefit, but no cure in keratosis pilaris, may be tried if all else has failed.
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