Br J Dermatol 2012;167:424–432 Hung SI, Chung WH, Liou LB, et al HLA-B*5801 allele as a genetic marker for severe cutaneous adverse reactions caused by allopurinol Proc Natl Acad Sci U S A 2005;102:4134–4139 Lee HY, Lim YL, Thirumoorthy T, et al The role of intravenous immunoglobulin in toxic epidermal necrolysis: a retrospective analysis of 64 patients managed in a specialized centre Br J Dermatol 2013;169:1304–1309 Mallal S, Nolan D, Witt C, et al Association between presence of HLA-B*5701, HLA-DR7, and HLA-DQ3 and hypersensitivity to HIV-1 reverse-transcriptase inhibitor abacavir Lancet 2002;359:727–732 Sassolas B, Haddad C, Mockenhaupt M, et al ALDEN, an algorithm for assessment of drug causality in Stevens-Johnson syndrome and toxic epidermal necrolysis: comparison with case-control analysis Clin Pharmacol Ther 2010;88:60–68 Wootton CI, Patel AN, Williams HC In a patient with toxic epidermal necrolysis, does intravenous immunoglobulin improve survival compared with supportive care? Arch Dermatol 2011;147:1437–1440 CHAPTER 69 ■ RASH: NEONATAL ADITI S MURTHY INTRODUCTION Rashes are common in the neonatal period and can cause significant parental distress The ability to distinguish worrisome rashes from those that are benign is of critical importance To provide a schema for understanding rashes in the neonate, it can be helpful to divide the rashes into categories: pustules, vesicles, patches/plaques, hamartomas, and dyspigmentation Within these categories, there are signs and symptoms that push the clinician to be more or less concerned PUSTULAR ERUPTIONS Pustular rashes in neonates are common and can be caused by inflammation (such as in erythema toxicum and transient neonatal melanosis) or infections (yeast, bacteria like Staphylococcus aureus, and, rarely, herpes simplex virus [please see vesicular neonatal rashes below for full discussion of herpes simplex]) The goal of recognition is to spare healthy infants with benign pustular eruptions extensive workups and not to miss those with more serious pustular eruptions Neonatal Acne Neonatal acne is a fairly common papular and pustular eruption of the forehead and face ( Fig 69.1 ) The etiology is possibly due to overgrowth of commensal yeasts Treatment is not always necessary as this can be self-limited Neonatal acne distinguished from true “acne” in the sense that unlike infantile or adolescent acne there are no comedones or scarring lesions Erythema Toxicum Neonatorum Erythema toxicum neonatorum (ETN) is usually evident within the first 48 hours of life The rash typically has mixed features with erythema, wheals, papules, and pustules ( Fig 69.2 ) This transient rash resolves spontaneously without sequelae over the course of to weeks Histologically, ETN shows an abundance of eosinophils Etiology is unclear One prospective study of 1,000 neonates suggested that risk factors include higher birth weight, greater gestational age, vaginal delivery, maternal age