Lauren Schock, BSc, MD Program, Cumming School of Medicine, University of Calgary, Calgary, AB.
Joseph M. Lam, MD, FRCPC, Clinical Associate Professor, Department of Pediatrics, Associate Member, Department of Dermatology
and Skin Sciences, University of British Columbia, Vancouver, BC.

Abstract
Yellow-hued papules and plaques in children can be difficult to differentiate as many causes are rare and may not be frequently outside of specialty pediatric dermatology settings. We will review some of the common and concerning yellow-brown papules and plaques found in infants and children and discuss appearance and distribution, pathophysiology, associated findings, and management.
Key Words: dermatology, pediatric, yellow lesions.

Introduction
Yellow and yellow-brown papules and plaques represent an array of underlying pathophysiology in children's dermatological diseases. The evaluation of these lesions can be challenging if they are not commonly encountered in practice. Understanding an approach to distinguishing yellow-brown lesions and related findings is important for practitioners to make timely diagnoses and appropriate referrals. Congenital or acquired appearance, and the number and distribution of lesions are important factors to aid in diagnosis. We will examine both common and uncommon lesions for practitioners to be aware of.

1. Congenital Lesions
1.1 - Nevus Sebaceous
A nevus sebaceous is a hamartoma—a benign tumour—of the sebaceous glands. Nevus sebaceous presents as a thin, sharply demarcated yellow to red plaque commonly presenting at birth. They are oval to linear in shape ranging from a few millimetres to a few centimeters. The surface may appear verrucous or waxy. About half of the lesions occur on the scalp, but can also occur on the face and neck. They are less common on the upper chest or arms. When on the scalp, the overlying area is usually hairless, making it one of the most common causes of congenital hair loss in children.¹

In adulthood, androgenic stimulation to the sebaceous glands within the lesion may cause the plaque to become verrucous. There is a small chance that benign tumors (1.6-2.8%) or malignant but slow growing basal cell carcinoma (0.9%) will grow within the lesion.² Rapidly growing nodules or plaques should be biopsied for pathologic evaluation, but is not needed for stable lesions. Barring cosmetic concerns, excision can be postponed until the teen or young adult years when they child can make an informed decision about removal, and general anesthetic can be avoided.

Infants with large nevus sebaceous on the face or scalp (larger than 10cm) should be screened for musculoskeletal, neurologic, ocular and cardiovascular involvement, which may be indicative of nevus sebaceous syndrome (also known as Schimmelpenning syndrome). Nevus sebaceous syndrome is characterized by neurologic abnormalities and potential ocular diseases. Some examples include seizures, developmental delay, hemiparesis, hypotonia, deafness, scoliosis, facial bone deformity, macrocephaly, and corneal changes. Treatment of nevus sebaceous syndrome is challenging and requires a multi-disciplinary approach.³