AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

Background

Eruptive vellus hair cysts (EVHCs) were first described in 1977 by Esterly and colleagues who reported 2 children with symmetrically distributed follicular papules on the chest and flexor extremities.¹ Histologically, these papules had the unique characteristic of dermal cysts containing small vellus hairs.

Cases of EVHC may either be acquired or inherited in an autosomal dominant fashion. Generally, they are isolated findings. However, they have been associated with other skin disorders (eg, anhidrotic ectodermal dysplasia, hidrotic ectodermal dysplasia, pachyonychia congenita).

Pathophysiology

EVHCs are thought to arise as a developmental abnormality of vellus hair follicles. A predisposition exists for follicular occlusion at the level of the infundibulum, which results in cystic dilatation of the proximal hair follicle and secondary atrophy of the hair bulb.

Frequency

International

The frequency is unknown. More than 50 cases have been reported in the literature; however, EVHCs may occur more frequently than is suggested by reports, possibly because the diagnosis is only definitively confirmed with biopsy.

Mortality/Morbidity

EVHCs are asymptomatic; however, they may be cosmetically bothersome. Morbidity may be associated with treatment of the disorder.

Race

EVHCs have no racial predilection.

Sex

Males and females are affected equally.

Age

In familial cases, EVHCs are first noted at birth or during infancy. In sporadic cases, cysts usually develop in the late-first or second decade of life.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

History

• EVHCs typically develop as an acneiform eruption on the chest and extremities.² EVHCs have also been reported on the eyelids and periorbital skin.³
• Often, no antecedent trauma or triggering factor is reported.
• EVHCs may be congenital or acquired. Several reports have noted familial cases in which the condition is thought to be inherited as an autosomal dominant trait.^{4, 5}
• EVHCs may be present at birth or arise in childhood.
• In sporadic cases, lesions typically arise in the first and second decades with the onset of puberty.

Physical

• EVHCs appear clinically as discrete follicular papules.
• • Papules may appear erythematous, yellow, bluish-gray, or even slightly brown.
  • The chest and flexor or extensor surfaces of the extremities are the most common sites of involvement.
  • Generalized EVHCs and facial variants are reported.
  • A single case report describes unilateral EVHCs of the face.⁶
• Patients may have just a few cysts, or, often, they may have several hundred.
• • More than 400 cysts were seen on a patient with generalized EVHC.
  • Cysts are usually dome-shaped with a smooth surface, measuring 1-4 mm in diameter.
  • Cysts sometimes demonstrate central puncta, hyperkeratotic crusts, or umbilication.
  • Mechanical irritation of the cysts may produce transepidermal elimination of retained vellus hairs, similar to that seen in perforating folliculitis.

Causes

EVHCs occur as a developmental abnormality of vellus hair follicles. A gradual disruption occurs between the proximal and distal parts of the follicle, usually at the level of the infundibulum. This results in the retention of hairs, cystic dilatation of the proximal follicle, and subsequent atrophy of the hair bulb.

EVHCs have also been considered a type of follicular hamartoma. The cyst wall may consist of keratinization patterns from different levels of the follicular infundibulum. The keratinization is generally that of the epidermis or the outer root sheath, but foci of trichilemmal keratinization have also been reported.

DIFFERENTIALS

Section 4 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

A single report describes EVHCs on the face, leading to blue-gray discoloration of the skin and mimicking nevus of Ota.⁷

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

Procedures

• Punch biopsy of the skin is the diagnostic procedure of choice.
• Alternatively, the diagnosis can be confirmed with a potassium hydroxide wet mount of cyst contents extruded through a small incision. Microscopic examination of the cyst contents reveals vellus hairs. The cyst can be anesthetized with a local or topical anesthetic prior to incision with a sterile blade or 18-gauge needle.
• In 2006, another extraction technique was described. Patients were treated with topical anesthetic prior to puncturing the surface of the cyst with a sharp-tipped electrocautery instrument. The cyst wall and contents were then dissected out with forceps and either sent to a pathology laboratory or examined microscopically with 10% potassium hydroxide to confirm the diagnosis of EVHC.⁸

Histologic Findings

Histopathology shows a cystic structure in the mid dermis arising from the infundibulum of a hair follicle. The cysts contain multiple cross-sections of vellus hairs and layered laminated keratinous material. They are lined by squamous epithelium 2- to 5-cells thick. Generally, no sebaceous glands are present in the cyst wall. A surrounding granulomatous reaction may be present, especially if the hairs disrupt the cyst wall.

The differential diagnosis of pilosebaceous cysts includes infundibular cysts, steatocystoma multiplex, and EVHCs. All 3 commonly affect the anterior chest and consist of asymptomatic papules or nodules. Obstructed or occluded follicles form the common infundibular cysts. These do not contain sebaceous glands or vellus hairs. The cysts of steatocystoma multiplex arise in the sebaceous duct and have a crenulated, eosinophilic, hyaline lining to the cyst wall where the granular layer is absent. Steatocystomas also contain sebaceous glands arising within the cyst wall.

Some authors believe that EVHC and steatocystoma multiplex are variants of the same disorder because both lesions have been reported in the same patient.⁹ Other authors have defended their status as distinct entities based on different histologic patterns. One study¹⁰ demonstrated differential expression of keratins 10 and 17. In 2 cases of EVHC, there was strong staining for K17 but no staining for K10. In 7 cases of steatocystoma, both K10 and K17 were expressed in the suprabasal cells of the cyst wall. In 5 epidermoid cysts, positive staining occurred only for K10.

Several reports note patients having cysts containing elements of both EVHCs and steatocystoma multiplex.^{11, 12, 13} The term hybrid cyst has been proposed to describe cysts containing combinations of EVHCs, steatocystoma multiplex, and epidermoid cysts. Some authorities argue that these cyst types all form from the pilosebaceous unit and are therefore all just a spectrum of the same disorder. Combinations of infundibular cysts, trichilemmal cysts, and pilomatricomas have also been described as hybrid cysts.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

Medical Care

Twenty-five percent of cases resolve spontaneously through transepidermal elimination.

• Keratolytics
• • Clinical benefit was reported after gentle mechanical dermabrasion with an exfoliating sponge (eg, Buf Puf, 3M; St. Paul, Minn) followed by an application of 10% urea cream.
  • Significant clinical improvement resulted in one case with 12% lactic acid applied to the affected areas.
• Retinoids
• • Topical tretinoin applied nightly to the affected area is a reasonably safe treatment option. This method reportedly cleared a case of congenital EVHC after only 5 applications, leaving only a slight residual erythema that gradually faded.
  • Topical tazarotene cream 0.1% applied to the affected area was shown to be more effective than some surgical options for the treatment of EVHC.¹⁴
  • Oral isotretinoin at 1 mg/kg/d produced no improvement in one patient after 20 weeks of therapy.¹⁵
  • Systemic vitamin A therapy (100,000 IU/d) has also been tried; however, this also produced no clinical improvement and resulted in severe headaches requiring discontinuation of therapy.

Surgical Care

• Needle evacuation of cysts can be performed using an 18-gauge needle after local anesthesia with a topical anesthetic (EMLA cream).¹⁶ This technique can also be used to aid in the diagnosis of EVHC. After extrusion, the cyst is examined histologically, pressed between a glass slide and cover slip with mineral oil. Multiple thin, fine hairs can be seen within the lumen of the thin cyst wall.
• Simple excision (eg, punch biopsy technique) removes the cyst; however, this is not practical for most cases of EVHCs because the cysts are too numerous and punch biopsy scars may be unsightly.
• Carbon dioxide laser vaporization has been effective for a case of EVHC on the face.¹⁷
• • A test spot was performed with the carbon dioxide laser (10,600-nm wavelength) at 5 watts of power, irradiance of 160 W/cm², a 2-mm spot size, and a pulse duration of 0.2 seconds.
  • No scarring occurred after treating the face in the same manner. Eyelid lesions were treated in the same manner except they used only 3 watts of power and 100 W/cm² irradiance.
  • Slight hyperpigmentation occurred at some of the treated sites; no hypertrophic scarring was noted. Cystic regeneration did not occur.
• Pulsed erbium:yttrium-aluminum-garnet (Er:YAG) laser has been reported effective in treating 2 patients with EVHCs on the trunk.¹⁸
• • The technique involved drilling with the Er:YAG laser (2940-nm wavelength) using a 2-mm spot size, 250-microsecond pulse duration at 60.5-63.7 J/cm², and a 1.9- to 2-J pulse energy.
  • Three to 5 stacked pulses were delivered, the cysts were expressed with digital pressure, they were extracted with forceps, the base of the cyst wall was further ablated with 3 pulses, and the area was allowed to heal by secondary intention.
  • The follow-up evaluation was performed only by telephone interview; patients reported no scarring, discoloration, or recurrence of the cysts. However, another report has suggested early recurrence of the cysts after treatment with Er:YAG laser to EVHC on the face.¹⁹

MEDICATION

Section 7 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Drug Category: Keratolytics

Modulate keratinocyte differentiation and decrease oil production.

Drug Name	Urea (Carmol, Keralac)
Description	Topical humectant. Promotes hydration and removal of excess keratin. Urea is a small molecule that osmotically binds water. Use 10% or 20% cream.
Adult Dose	Apply qd/tid to affected areas
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity; severely impaired renal function, active intracranial bleeding, marked dehydration, or frank liver failure; infusion into veins of lower extremities in elderly persons may cause phlebitis and thrombosis; open blisters
Interactions	Systemic administration may decrease effects of lithium
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Precautions apply to IV administration of urea; do not use if intracranial bleeding present, unless prior to surgical intervention to control hemorrhage (reduction of brain edema by urea may result in reactivation of intracranial bleeding); may increase risk of venous thrombosis and hemoglobinuria in hypothermic patients; caution in renal impairment

Drug Category: Retinoids, Topical

Drug Name	Tazarotene (Tazorac, Avage)
Description	Retinoid prodrug whose active metabolite modulates differentiation and proliferation of epithelial tissue; may also have anti-inflammatory and immunomodulatory properties. Available as 0.05% and 0.1% cream and gel.
Adult Dose	Apply sparingly to affected area qhs
Pediatric Dose	Children: Not established Adolescents: Administer as in adults
Contraindications	Documented hypersensitivity.
Interactions	Do not use concomitantly with dermatologic drugs or cosmetics that have a strong drying effect on the skin (eg, salicylic acid, benzoyl peroxide, astringents)
Pregnancy	X - Contraindicated; benefit does not outweigh risk
Precautions	Erythema and peeling may occur at application site

MISCELLANEOUS

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to inform patients about the possible adverse effects of treatment because the primary morbidity associated with this disorder may be related to treatment

Special Concerns

• EVHCs have been reported in 2 cases of pachyonychia congenita.^{20, 21} Pachyonychia congenita is an autosomal dominant disorder associated with palmoplantar hyperkeratosis, dystrophic nails, oral leukoplakia, follicular hyperkeratosis, and corneal abnormalities. Several cases have been associated with other types of multiple cutaneous cysts (eg, steatocystoma multiplex, epidermoid cysts).
• A case report has also linked EVHCs with hidrotic ectodermal dysplasia.²² The patient had sparse hair and disabling palmoplantar hyperkeratosis. Incidentally, the patient was taking oral etretinate at 1 mg/kg/d for more than 2 years, which resulted in improvement of her keratoderma but did not alleviate the EVHCs.
• EVHCs have also been reported in association with anhidrotic ectodermal dysplasia.²³ In anhidrotic ectodermal dysplasia, patients have a greatly reduced number of eccrine sweat glands and sebaceous glands, resulting in difficulties with temperature regulation. Other clinical features include sparse hair, brittle nails, and teeth abnormalities.
• Two cases of eruptive vellus hair cysts were reported in association with renal failure. Both cases were reported in 58-year-old Japanese patients with acquired renal disease on hemodialysis.²⁴ EVHCs were confirmed by skin biopsy from the cervical region in both cases. They hypothesize that advanced glycation end product may play a role in the development of the cystic structures in these patients; however, cause and effect have not been shown.
• A possible link has been suggested between neurologic abnormalities and EVHCs. Morgan et al²⁵ reported a patient with developmental delay, mild intellectual impairment, and congenital EVHCs. They noted 2 other patients with incidental seizure disorders and EVHCs as corroborating evidence; however, at this point, no definite evidence supports a new neurocutaneous syndrome involving EVHCs.
• One report describes EVHC occurring in a patient with Lowe syndrome. Lowe syndrome is an X-linked recessive oculocerebrorenal syndrome with mutations of Xq24-26.1. The authors suggest that a defect in the oculocerebrorenal-Lowe 1 gene (OCRL1) may account for the cyst formation. Features of Lowe syndrome include renal failure, mental retardation, and eye abnormalities.²⁶

MULTIMEDIA

Section 9 of 10  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

Media file 1:  Clinical photo of eruptive vellus hair cysts showing involvement on the patient's chest.
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Media file 2:  Histopathology of an eruptive vellus hair cyst showing a middermal cyst with squamous epithelium.
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Media file 3:  A close-up view of the contents of an eruptive vellus hair cyst showing cross-sections of vellus hairs and laminated keratinous material.
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Media file 4:  Eruptive vellus hair cysts in the axilla.
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Media file 5:  The patient seen here is expanding his cheek with air to better demonstrate multiple eruptive vellus hair cysts on the face.
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Media type:  Photo

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Miscellaneous
• Multimedia
• References

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11. Ahn SK, Chung J, Lee WS, Lee SH, Choi EH. Hybrid cysts showing alternate combination of eruptive vellus hair cyst, steatocystoma multiplex, and epidermoid cyst, and an association among the three conditions. Am J Dermatopathol. Dec 1996;18(6):645-9. [Medline].
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15. Urbina-González F, Aguilar-Martínez A, Cristóbal-Gil MC, Sánchez de Paz F. The treatment of eruptive vellus hair cysts with isotretinoin. Br J Dermatol. Mar 1987;116(3):465-6. [Medline].
16. Sárdy M, Kárpáti S. Needle evacuation of eruptive vellus hair cysts. Br J Dermatol. Sep 1999;141(3):594-5. [Medline].
17. Huerter CJ, Wheeland RG. Multiple eruptive vellus hair cysts treated with carbon dioxide laser vaporization. J Dermatol Surg Oncol. Mar 1987;13(3):260-3. [Medline].
18. Kageyama N, Tope WD. Treatment of multiple eruptive hair cysts with erbium:YAG laser. Dermatol Surg. Oct 1999;25(10):819-22. [Medline].
19. Coras B, Hohenleutner U, Landthaler M, Hohenleutner S. Early recurrence of eruptive vellus hair cysts after Er:YAG laser therapy: case report and review of the literature. Dermatol Surg. Dec 2005;31(12):1741-4. [Medline].
20. Lee HT, Chang SH, Yoon TY. Eruptive vellus hair cyst in a patient with pachyonychia congenita. J Dermatol. Jun 1999;26(6):402-4. [Medline].
21. Takeshita T, Takeshita H, Irie K. Eruptive vellus hair cyst and epidermoid cyst in a patient with pachyonychia congenita. J Dermatol. Oct 2000;27(10):655-7. [Medline].
22. Romiti R, Festa Neto C. Eruptive vellus hair cysts in a patient with ectodermal dysplasia. J Am Acad Dermatol. Feb 1997;36(2 Pt 1):261-2. [Medline].
23. Köse O, Tastan HB, Deveci S, Gür AR. Anhidrotic ectodermal dysplasia with eruptive vellus hair cysts. Int J Dermatol. Jun 2001;40(6):401-2. [Medline].
24. Mieno H, Fujimoto N, Tajima S. Eruptive vellus hair cyst in patients with chronic renal failure. Dermatology. 2004;208(1):67-9. [Medline].
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26. Nandedkar MA, Minus H, Nandedkar MA. Eruptive vellus hair cysts in a patient with Lowe syndrome. Pediatr Dermatol. Jan-Feb 2004;21(1):54-7. [Medline].
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29. Fisher DA. Retinoic acid in the treatment of eruptive vellus hair cysts. J Am Acad Dermatol. Aug 1981;5(2):221-2. [Medline].
30. Haynie LS, Taylor RM. Blue papules on the chest. Eruptive vellus hair cysts. Arch Dermatol. Jul 1988;124(7):1103, 1106. [Medline].
31. Hong SD, Frieden IJ. Diagnosing eruptive vellus hair cysts. Pediatr Dermatol. May-Jun 2001;18(3):258-9. [Medline].
32. Kumakiri M, Takashima I, Iju M, Nogawa M, Miura Y. Eruptive vellus hair cysts--a facial variant. J Am Acad Dermatol. Oct 1982;7(4):461-7. [Medline].
33. Kwon KS, Lee HT, Jang HS, Chung TA, Oh CK. A case of generalized eruptive vellus hair cysts. J Dermatol. Aug 1997;24(8):556-7. [Medline].
34. Nogita T, Chi HI, Nakagawa H, Ishibashi Y. Eruptive vellus hair cysts with sebaceous glands. Br J Dermatol. Nov 1991;125(5):475-6. [Medline].
35. Requena L, Sánchez Yus E. Follicular hybrid cysts. An expanded spectrum. Am J Dermatopathol. Jun 1991;13(3):228-33. [Medline].
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Article Last Updated: Nov 13, 2007