Educational objectives

At the conclusion of this activity, participants will be able to:

• Recognize the lesions described in the case and shown in the photograph
• Describe clinical features and differential diagnosis
• Explain to the family the nature of these lesions and expected outcome

CME credit

This is an article from The Child's Doctor, Spring 2006 issue. You may take the quiz for learning purposes, but credits are no longer valid.

Author disclosures

Dr. Chamlin is a consultant for Novartis and Astellas. She does not refer to products that are still investigational or not labeled for the use in discussion.

Dr. Abrams has no industry relationship to disclose and does not refer to products that are still investigational or not labeled for the use in discussion.

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A 7-year old female presented with a 1 1⁄2 year history of lesions that started on her chest and spread to involve her proximal arms and legs. The lesions were occasionally pruritic. Her past medical history was significant for chronic constipation. Family history was negative for skin disease or similar lesions. Physical examination revealed monomorphous brown papules measuring 1 mm to 2 mm in diameter. These papules were scattered over the mid and lower chest (Figure 1) as well as her upper abdomen. The bilateral inner upper arms showed similar but lighter brown papules. There were a few lesions on her anterior legs.

FIGURE 1: Photograph of a child's chest shows multiple 1 mm to 2 mm brown dome-shaped papules.

What is the most likely diagnosis?

A. Keratosis pilaris

B. Acneiform eruptions

C. Eruptive vellus hair cysts

D. Molluscum contagiosum

Answer: C

Discussion:

Eruptive vellus hair cysts were first described in 1977 by Esterly et al.[1] The lesions are seen most commonly in the pediatric population, but are reported in all ages. The lesions are seen equally in males and females, and inheritance is sporadic or autosomal dominant. There is no racial predilection.

The cutaneous lesions are small flesh-colored, brown, or red-brown papules scattered or grouped on the chest and upper extremities. The head, neck, buttock and lower extremities may also be affected.[2] The number of lesions varies from 20 to 200. Development of these lesions is initially quite rapid and then follows a static course.[3] Most cases are asymptomatic, but pruritus has been reported.[4]

The etiology of eruptive vellus hair cysts is unknown. Esterly et al[1] suggested that these lesions arise from an abnormality in the development of vellus hair follicles that predisposes these follicles to occlude at the infundibular level.

Diagnosis can often be made on the presence of clinical features alone. Alternatively, one can perform an incision at the top of a superficial lesion using either an #11 blade or 18-gauge needle and express the cystic material. Preparation of these contents with potassium hydroxide reveals numerous vellus hair cysts under the microscope.[5,6] If the diagnosis remains uncertain, a biopsy can be performed. Histopathology of lesional skin demonstrates cystic structures lined by several layers of squamous epithelium and filled with laminated keratin material. Multiple transverse and oblique vellus hair shafts are found within the cyst.[7]

The differential diagnosis includes keratosis pilaris, acneiform eruptions, folliculitis, molluscum contagiosum, lichen nitidus and milia. The distribution of keratosis pilaris is typically symmetric involving the extremities and buttock. Acne can be papular, but other features including pustules, comedones or nodules should also be present. Similarly, folliculitis consists of pustular lesions. Molluscum contagiousum tends to exhibit a characteristic central core and inclusion bodies would be visualized in a KOH preparation. Lichen nitidus involves skin colored flat topped papules, and milia tend to be pearly white papules.

Eruptivevellus hair cysts rarely respond to any known therapy. The literature has reported a few cases that responded to topical retinoic acid and 12% lactic acid[8,9] as well as laser treatments, both pulsed CO2 and erbium:YAG.[10] Most cases show spontaneous resolution.[3] Parents should be educated regarding the benign nature of these lesions, their lack of response to known treatment modalities, and their probable spontaneous resolution over several years.

REFERENCES

[1.] Esterly NB, Fretzin DF, Pinkus H. Eruptive vellus hair cysts. J AM Acad Dermatol 1977;113:500-503.

[2.] Lee S, Kim JG. Eruptivevellus hair cyst: Clinical and histologic findings. Arch Dermatol 1984;120:1191-1195.

[3.] Schachener LA, Hansen RC. Pediatric Dermatology, 3rd ed. Edinburgh; New York: Mosby; 2003:542-543.

[4.] Piepkorn MW, Clark L, Lombard DL. A kindred with congenital vellus hair cysts. J AM Acad Dermatol 1981;5:661-665.

[5.] Hong SD, Frieden IJ. Diagnosing eruptive vellus hair cysts. Pediatric Dermatology 2001;18:258-259.

[6.] Sardy M, Karpati S. Needle evacuation of eruptive vellus hair cysts. Br J Dermatol 2000;141:595.

[7.] Reep MD, Robson KJ. Eruptive vellus hair cysts presenting as multiple periorbital papules in a 13-year old boy. Pediatric Dermatology 2002;19:26-27.

[8.] Urbina-Gonzalez F, Aguilar-Martinez A, Cristobal-Gil MC, Sanchez de Paz F. The treatment of eruptive vellus hair cysts with isotretinoin. Br J Dermatol 1987;116(3):465-466.

[9.] Bovenmyer DA. Eruptive vellus hair cyst: Clinical and histologic findings. Arch Dermatol 1979;115:338-339.

[10.] Kageyama N, Tope WD. Treatment of multiple eruptive vellus hair cysts with erbium:YAG laser. Dermatol Surg 1999;25:819-822.