A yellow-orange hairless patch on a 1-year-old

Nevus sebaceous was first described in 1895 by Josef Jadassohn. As a result, this condition is also referred to as nevus sebaceous of Jadassohn or organoid nevus. Nevus sebaceous is a benign hamartoma of the skin involving immature hair follicles,...

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Nevus sebaceous was first described in 1895 by Josef Jadassohn. As a result, this condition is also referred to as nevus sebaceous of Jadassohn or organoid nevus. Nevus sebaceous is a benign hamartoma of the skin involving immature hair follicles, epidermal cells, sebaceous glands, and apocrine glands.^1-4 There is equal incidence in males and females, and two-thirds of cases are present at birth.⁵ Other cases develop during infancy or early childhood. Very few familial cases have been described, as most cases seem to occur sporadically.^6-9

Nevus sebaceous appears most frequently on the head, with 50% of cases on the scalp. They appear as oval or linear verrucous plaques that range in size. In early childhood, the plaque appears slightly raised or smooth, yellow, waxy, and hairless. After puberty, secondary to hormonal influence, the plaques tend to become scaly, bumpy, and papular. These changes are due to epidermal growth and an increase in the number of sebaceous glands during puberty. The verrucous changes that occur during puberty can be alarming, and are a common cause for dermatology visits. In 20% of nevus sebaceous cases, a neoplastic growth develops within the nevus. Most commonly, benign adnexal neoplasms arise within nevus sebaceous lesions, such as trichoblastomas and syringocystadenoma papilliferum. However, malignant neoplasms such as basal cell carcinoma can also arise within the nevi. Thus, atypical changes within a nevus sebaceous lesion must be biopsied to rule out malignant transformation.^1-4

Histology of nevus sebaceous is characterized by immature hair follicles. Before puberty, there are few immature sebaceous glands. After puberty, hyperplasia of sebaceous glands and apocrine glands, as well as epidermal hyperplasia, are apparent. The sebaceous glands can be located more superficially within the dermis than they usually are.

Nevus sebaceous of Jadassohn syndrome is a rare combination of linear nevus sebaceous, epilepsy, and intellectual disability. In nevus sebaceous syndrome, the plaque tends to be linear and large (≥10 cm), and spans multiple dermatomes.¹⁰ Other areas involved in this congenital syndrome include ocular, skeletal, vascular, and urogenital systems. Neurologic assessments and imaging should also be performed to identify or rule out rare abnormalities, especially if the plaque is large and located in the centrofacial area.

The differential diagnosis of nevus sebaceous includes juvenile xanthogranuloma, epidermal nevus, and the syringocystadenoma papilliferum. Juvenile xanthogranuloma is a rare, benign disorder of dermal dendrocytes that presents in early childhood as red to yellow plaques with papules. They are located commonly on the head, neck, and upper trunk. Histology shows mononuclear cells and multinucleated giant cells, some of which may have features of Touton giant cells.^2-5 Epidermal nevi are benign hamartoma of the skin that present on the torso or limbs, but rarely on the scalp or face. These brown or skin-colored papules appear along the lines of Blaschko. Histology demonstrates flattened papillary projections of the epidermis and orthokeratotic hyperkeratosis.^1-3Syringocystadenoma papilliferum is a rare, benign tumor of the apocrine sweat glands. Commonly located on the scalp, syringocystadenoma papilliferum exists as an isolated papule or is associated with nevus sebaceous. Histology is characterized by papillomatous epidermal invaginations of basilar cuboidal cells surrounded by 2 layers of columnar cells. Apocrine secretory cells are present as the inner layer.^1-5

Diagnosis of nevus sebaceous is usually based on clinical examination findings of a raised, yellow-orange, hairless verrucous plaque on the face or scalp. When the diagnosis of nevus sebaceous is suspected, the lesion should be observed closely but does not have to be surgically removed. Historically, surgery used to be the initial treatment. New studies showing the lower rates of malignant degeneration have caused a shift to less aggressive management. However, some parents of children with nevus sebaceous prefer to have the lesions excised for cosmetic reasons. If the parents and clinician decide to observe the lesion, they should expect the lesion to darken and thicken during puberty. However, the family and clinician should be suspect of any new growths within the lesion that may herald the formation of a benign (trichoblastoma or syringocystadenoma papilliferum) or malignant (basal cell carcinoma) neoplasm within the nevus sebaceous lesion. In the event of the a new growth within the nevus sebaceous lesion, the lesion should be biopsied to rule out malignancy.¹⁰

The patient in this vignette was diagnosed with nevus sebaceous. The natural progression of the lesion was explained to the mother, who then opted to observe the lesion closely rather than elect surgical removal.

Michelle Lee, BA, is a medical student at the Baylor College of Medicine in Houston, David Rizk, BA, is a medical student at the University of South Alabama in Mobile, and Connie Wang, MD, is a dermatology resident at the Baylor College of Medicine in Houston.

References

1. Jaqueti G, Requena L, Sánchez Yus E. Trichoblastoma is the most common neoplasm developed in nevus sebaceus of Jadassohn: a clinicopathologic study of a series of 155 cases. Am J Dermatopathol. 2000;22:108-118.
2. Cifuentes L, Ziai M. Images in clinical medicine. Nevus sebaceous. N Engl J Med. 2012;366:1923-1923.
3. Schachner LA, Hansen RC. Pediatric Dermatology. Maryland Heights, MO: Mosby Elsevier; 2011.
4. Ujiie H, Kato N, Natsuga K, Tomita Y. Keratoacanthoma developing on nevus sebaceous in a child. J Am Acad Dermatol. 2007;56(2 suppl):S57-S58.
5. Habif TP, Campbell JL Jr, Chapman MS, Dinulos JG, Zug KA. Benign skin tumors. In: Habif TP, Campbell JL Jr, Chapman MS, Dinulos JG, Zug KA, eds. Skin Disease: Diagnosis and
6. Hughes SM, Wilkerson AE, Winfield HL, Hiatt KM. Familial nevus sebaceus in dizygotic male
7. Happle R, König A. Familial naevus sebaceus may be explained by paradominant transmission. Br J Dermatol. 1999;141:377.
8. Levinsohn JL, Tian LC, Boyden LM, et al. Whole-exome sequencing reveals somatic mutations in HRAS and KRAS, which cause nevus sebaceus. J Invest Dermatol. 2013;133:827-830.
9. Kim D, Benjamin LT, Sahoo MK, Kim J, Pinsky BA. Human papilloma virus is not prevalent in nevus sebaceus. Pediatr Dermatol. 2014;31:326-330.
10. James WD, Berger TG, Elston DM, Neuhaus IM. Andrew’s Diseases of the Skin: Clinical Dermatology. 11th ed. Philadelphia, PA: Elsevier; 2011.