A 9-year-old girl born out of a non-consanguineous marriage presented with asymptomatic small blue-green bumps on the upper back for the past 5 years. Similar lesions had appeared on her father's trunk in the late second decade of his life. The lesions were gradually increasing in number and extent. The other family members were unaffected by this condition. The girl was also on treatment for cutaneous lichen planus from a private clinic.
Besides mild scoliosis and supraumbilical hernia, rest of the physical and systemic examination in the child was unremarkable. On cutaneous examination, annular hyperpigmented lesions were seen on the trunk and upper limbs, suggestive of partially treated annular lichen planus (Fig. 1a). Also, multiple, small, dome-shaped, bluish green papules were noted bilaterally on the back of shoulders and chest, relatively sparing the midline (Fig. 1b). The papules situated on the trunk of the father had similar morphologic characteristics and distribution (Fig. 1c). The contents extracted from one of the papules on the daughter's skin using a hypodermic needle revealed multiple coiled hairs entangled in keratinous debris, and microscopic examination using 10% potassium hydroxide showed coiled vellus hairs (Fig. 2).
Fig. 1.
a A 9-year-old female with scoliosis, supraumbilical hernia (red arrow), and cutaneous lichen planus (blue arrow). b Multiple bluish green papules on the back of her shoulder and chest (red arrow). c Multiple bluish green papules on the back of trunk in the father (red arrow).
Fig. 2.
Needle extraction revealing coiled hairs and microscopy using potassium hydroxide (×10) showing multiple vellus hairs.
Punch biopsy was performed, which revealed a mid-dermal cyst lined by squamous epithelium that contained lamellated keratin and numerous vellus hair shafts in its cavity (Fig. 3a). On immunohistochemistry (IHC), keratinocytes of the cyst wall strongly expressed cytoplasmic keratin 1/10 and calretinin and nuclear p63. Nuclear positivity for Ki-67 was observed in about 10–15% of basal layer keratinocytes (Fig. 3b). No expression of keratin 7 and 20 and epithelial membrane antigen was noted. The diagnosis was made, and topical tretinoin 0.025% was prescribed. No improvement was noted in the skin lesions even after 8 weeks of treatment.
Fig. 3.
a Photomicrograph showing a mid-dermal cyst lined by squamous epithelium and cavity containing laminated keratinous material and multiple vellus hair shafts (black arrow) (haematoxylin and eosin stained, ×10). b IHC (×10) showing nuclear positivity for Ki-67 in 10–15% of the basal layer cells (black arrow). IHC, immunohistochemistry.
What is your diagnosis?
Diagnosis: familial eruptive vellus hair cysts
Eruptive vellus hair cysts (EVHCs) are unusual developmental disorders of vellus hair follicles that clinically manifest as multiple, asymptomatic, and monomorphic papules on the skin. These may be skin colored or bluish green and are usually dome-shaped, soft tender papules with smooth surface, chiefly affecting the anterior chest, upper trunk, and upper limbs [1]. The histopathological findings of EVHCs are monomorphic too, characterized by collection of multiple horizontally and obliquely sectioned vellus hair shafts in a cystic cavity [1, 2, 3]. Reduced Ki-67 expression on IHC suggests that EVHCs are clinically stable lesions with a low proliferation rate [4].
Since the first description of EVHCs by Esterly et al. [5] in 1977, more than 220 cases have been reported, most of which were sporadic in origin [1]. Only 16 White, 2 Asian, and 1 Hispanic family were reported to have EVHCs in 2 or more successive generations but not in all offsprings, indicating an autosomal dominant transmission with incomplete penetrance [1]. We are reporting familial EVHCs in an Indian family, where the daughter seemed to have inherited the condition from her father through autosomal dominant mode. The lesions of EVHCs in family members usually have a similar distribution, which is in agreement with the present cases [1]. Usually, the EVHC located on the trunk is distributed near the midline, whereas in the present cases, the midline was relatively spared [1].
EVHCs may be easily mistaken for conditions with similar clinical presentations such as comedonal acne, milia, steatocystoma multiplex, keratosis pilaris, and syringomas [2, 3]. It is likely that EVHCs are underdiagnosed due to the lack of awareness about this entity amongst the dermatologists. In cases with diagnostic confusion, skin biopsy or less invasive techniques like needle extraction, microscopy, and dermoscopy may be beneficial (Table 1) [4, 6, 7, 8, 9]. In the present case, the peculiar clinical features in the daughter and the father, the striking findings of needle extraction, microscopy, and histopathology with IHC led us to the diagnosis of familial EVHC.
Table 1.
Clinical signs (needle extraction), dermoscopic findings, and histologic features of differential diagnoses of EVHCs
| Skin condition | Contents on needle extraction | Dermoscopy | Histopathology |
|---|---|---|---|
| Comedonal acne | Keratin combined with sebum | Numerous, homogenous areas, light and dark-brown, sometimes black, depending on the type of acne, open or closed comedones, predominantly circular, and situated superficially | Cystic hair follicle with keratinous material; may be open or closed |
|
| |||
| Milia | Keratin | White to yellow homogeneous areas occupying whole lesion, brownish peripheral rim, linear vessels (higher magnification with polarized mode) | Keratin-containing intradermal cyst lined by stratified epithelium with a granular layer; IHC: K10, filaggrin-positive |
|
| |||
| Steatocystoma multiplex | An oily, yellow liquid (predominantly acellular, granular debris, rare anucleated squamous cells and rare cholesterol crystals) | Yellow homogeneous area covering entire lesion, linear vessels, and peripheral brown rim | Mid-dermal cysts characterized by folded and crenated cyst wall, lined by stratified squamous epithelium with wavy corrugated eosinophilic cuticle towards the luminal surface, no granular layer seen; IHC: K10, K17 positive |
|
| |||
| Syringomas | Brownish pseudo-network occupying whole lesion and tiny white dots (correspond to sweat duct openings) | Presence of multiple small ducts and epithelial cords within the dermis. The ducts are lined by 2 rows of flattened epithelial cells, the outer layer bulging outwards to create a comma-like tail. Ductal lumina are filled with an amorphous, periodic acid-Schiff-positive material React strongly with S-100, CEA, EMA, lysozymes, and antibodies to GCDFP-15 and GCDFP-24 |
|
|
| |||
| Keratosis pilaris | Presence of vellus hairs that are frequently coiled, semicircular or looped, peri-follicular erythema, peri-pilar casts, vascular ectasias | The triad of epidermal hyperkeratosis, hypergranulosis, and plugging of individual hair follicles; mild superficial perivascular lymphocytic inflammatory changes in upper dermis | |
|
| |||
| EVHCs | Coiled vellus hair entangled in keratinous debris | 1. Presence of multiple brownish, round-to-oval structures (with/without erythematous to brownish halo) 2. Presence of central/eccentric pores 3. Blue homogenous areas 4. Peripherally arranged radial capillaries (may or may not be present) |
Mid-dermal cysts lined by squamous epithelium that contain lamellated keratin and numerous vellus hair shafts in its cavity; IHC: K1/10, K17, Ki67, p63, and calretinin-positive |
EVHC, eruptive vellus hair cyst; IHC, immunohistochemistry.
Furthermore, EVHCs have been observed in association with various dermatological and non-dermatological conditions, of which the link with steatocystoma multiplex has been discussed at length [1, 10, 11, 12]. None of the previous cases had associated lichen planus or hernia and only 1 case had scoliosis [1]. It is likely that the associations in this child such as lichen planus, supraumbilical hernia, and scoliosis were coincidental and did not share a pathogenetic link with EVHC.
EVHCs are mainly a cosmetic concern to the patients, but difficult to treat. We prescribed topical tretinoin 0.025% which showed no benefits. Although various treatment modalities for EVHCs have been tried such as topical retinoids, electrocautery, incision/excision, CO2 laser, and Erbium-YAG laser, but they failed to provide complete remission [1, 2, 3, 13]. Therefore, studies concerning pathogenetic mechanisms of EVHCs and potential therapeutic options for EVHCs are warranted in future.
Statement of Ethics
Written informed consent was obtained from the patient's parent for publication of this case report and any accompanying images. Ethical approval was not required (from Institutional Ethical Committee).
Conflict of Interest Statement
The authors have no conflict of interests to declare.
Funding Sources
There were no funding sources for the preparation of the manuscript.
Author Contributions
All authors contributed to conception and design of work, drafting of manuscript, and editing and final approval of the manuscript.
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