Derm Dx: A 'warty' patch on the scalp - Clinical Advisor

Derm Dx: A ‘warty’ patch on the scalp

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  • Nevus Sebaceus_1113 Derm Dx

A 13-year-old patient complains of a patch of skin on his occipital scalp that is brown and warty.

He was born with a bald spot in the same location and his parents state that the skin was initially smooth and flat. Two years ago the skin started thickening and developing a warty texture.

Nevus sebaceus, also called organoid nevus, is a congenital malformation of the skin. It is characterized by hyperplasia of the epidermis, immature sebaceous and apocrine glands and immature hair follicles. Lesions appear initially as hairless waxy yellow to pink patches,...

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Nevus sebaceus, also called organoid nevus, is a congenital malformation of the skin. It is characterized by hyperplasia of the epidermis, immature sebaceous and apocrine glands and immature hair follicles.

Lesions appear initially as hairless waxy yellow to pink patches, most commonly on the scalp or the face. There are a few case reports of nevus sebaceus on the neck and trunk. The lesions tend to thicken with time and display a warty appearance — most commonly at the time of puberty.1 Nevus sebaceus is found in 0.3% of newborns, with no predilection for sex. The disease is usually sporadic but familial cases are reported in the literature.2

Nevus sebaceus is usually apparent at birth but can present later in life, with the vast majority of cases apparent during puberty. Lesions are most commonly found on the scalp, with a well-localized area of alopecia being a hallmark of scalp disease. The size of lesions varies from one to several centimeters.

The exact incidence and risk of secondary carcinoma development is unknown. It was previously thought that over 10% of lesions develop into carcinoma, although this figure is now known to be overestimated. In a recent case series of 631 patients with nevus sebaceus, less than 1% of patients had an associated basal cell carcinoma, and 2.2% of patients had a benign tumor.3

Becker’s nevus classically manifests as light to dark-brown patches or plaques that appear unilaterally on the shoulder, trunk or arm. The lesions typically present during childhood, most commonly during puberty. Hypertrichosis is present in approximately 50% of cases.

Nevus comedonicus is a benign hamartoma with lesions presenting as groups of linear dilated follicular openings with dark keratin plugs resembling the comedones of acne vulgaris.

Inflammatory linear verrucous epidermal neoplasm (ILVEN) is a rare disease with an unknown etiology. It bears some resemblance to psoriasis. Lesions typically present as multiple erythematous scaly papules that coalesce to form a linear verrucous (wart-like) plaque, usually on a limb.

Diagnosis & Treatment

The diagnosis of nevus sebaceus is typically made by skin examination, based upon the findings of a slightly raised, yellow to pink plaque located on the scalp of the face. Infrequently these lesions may present on the neck or the trunk. In teenagers and adults, nevus sebaceus typically has a verrucous or nodular appearance.

If the diagnosis remains unknown from skin examination, a tissue biopsy should be performed. Histological findings include immature hair follicles, hyperplastic and immature sebaceous glands, apocrine glands and epidermal hyperplasia.4

Treatment

As it was previously thought that nevus sebaceus not uncommonly gave rise to secondary neoplasm, excision was the convention of therapy. It is now known that the risk of developing secondary carcinoma is low. Some authors state that the risk of transformation to basal cell carcinoma is less than 1%.3 More commonly, benign tumors may develop – syringocystadenoma, trichoblastoma or sebaceoma – and pose no risk to the patient.

Nonetheless, most patients find nevus sebaceus to be cosmetically unacceptable and will elect to have the lesion excised. Extirpation, or total surgical removal, is the treatment of choice. Removal by shave or laser ablation is usually not successful.

Christopher Downing, MD, is a dermatology research fellow at the Center for Clinical Studies in Houston, TX.  

Adam Rees, MD, is a graduate of the University of California Los Angeles School of Medicine and a resident in the Department of Dermatology at Baylor College of Medicine also in Houston.

References

  1. Bolognia J, Jorizzo J, Shaffer J. “Chapter 111 – Adnexal Neoplasms.” Dermatology 3rd Edition. St. Louis, Mo.: Saunders, 2012. Print. 
  2. Hughes SM, Wilkerson AE, Winfield HL, Hiatt KM. Familial nevus sebaceus in dizygotic male twins. J Am Acad Dermatol. 2006; 54: S47. 
  3. Simi CM, Rajalakshmi T, Correa M. “Clinicopathologic analysis of 21 cases of nevus sebaceus: a retrospective study.” Indian J Dermatol Venereol Leprol. 2008; 74:625. 
  4. Rosen H, Schmidt B, Lam HP et al. “Management of nevus sebaceus and the risk of Basal cell carcinoma: an 18-year review.” Pediatr Dermatol. 2009; 26:676. 
  5. Moody MN, Landau JM, Goldberg LH. “Nevus sebaceus revisited.” Pediatr Dermatol. 2012; 29:15.
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