Follicular papules on a boy’s chest and extremities

A 12-year-old boy presents with minimally pruritic papules on his chest.The Case

You are asked to evaluate a 12-year-old boy with minimally itchy papules on his chest and upper arms that suddenly appeared 2 years ago. His mother is a bit anxious because she has seen a pediatrician and 2 dermatologists who failed to make a diagnosis.

Diagnosis: Vellus hair cysts

Vellus hair cysts are just 1 of many types of follicular-derived cysts. They typically present on the chest, neck, flexures of the arms and legs, axilla, and sometimes the face. The lesions are usually skin colored, but may be light pink or tan. They most commonly present as multiple, small, dome-shaped papules, 1 mm to 4 mm in diameter and topped with hyperkeratotic crust, puncta, and/or umbilication. Vellus hair cysts have been known to be transmitted via autosomal dominant form, but can also be sporadic. They are asymptomatic and appear without antecedent trauma or inflammation.^1,2

Occasionally, vellus hair cysts are associated with genodermatoses such as steatocystoma multiplex (SCM), pachyonychia congenita, ectodermal dysplasia, Lowe syndrome, and chronic renal failure.^2,3 Although the pathogenesis is unclear, some have implicated the role of developmental anomalies of vellus hair follicles that predispose to infundibular occlusion or benign follicular hamartomas differentiating toward vellus hairs.

Differential diagnosis

Differential diagnosis includes SCM, keratosis pilaris, juvenile acne, folliculitis, molluscum contagiosum, and milia, among others.² The physical finding of vellus hairs popping out of the lesions when they are scratched is diagnostic.

Management

A quarter of cases resolve without treatment. However, when the eruption is persistent or bothersome to the patient, lesions may respond to topical keratolytics such as lactic acid (12%), topical retinoids, or glycolic acid.² In addition, neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, incision, and curettage may be helpful.

Our patient

The mother of our patient was reassured by the diagnosis, and because the eruption was not symptomatic, she elected to use emollients and to allow us to follow the patient with the primary care physician.

REFERENCES

1. Patel U, Terushkin V, Fischer M, Kamino H, Patel R. Eruptive vellus hair cysts. Dermatology Online Journal, 2012;18(12):7. Available at: http://escholarship.org/uc/item/0dz2b51s. Accessed April 15, 2014.

2. Zaharia D, Kanitakis J. Eruptive vellus hair cysts: report of a new case with immunohistochemical study and literature review. Dermatology. 2012;224(1):15-19.

3. Khatu S, Vasani R, Amin S. Eruptive vellus hair cyst presenting as asymptomatic follicular papules on extremities. Indian Dermatol Online J. 2013;4(3):213-215.

Dr Sami is a pediatric resident at Sinai Hospital of Baltimore, Maryland. Dr Cohen, section editor for Dermcase, is professor of pediatrics and dermatology, Johns Hopkins University School of Medicine, Baltimore. The author and section editor have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article. Vignettes are based on real cases that have been modified to allow the author and section editor to focus on key teaching points. Images may be substituted for teaching purposes.