Unilateral erythema in a newborn

Abstract

A 10-day-old newborn male was referred to our clinic for the evaluation of congenital dermal melanocytosis. During the physical examination, when the baby was lying on his side, a sharply demarcated erythema involving half of his body was noticed (Figure 1). The change of colour lasted a few minutes. The baby was otherwise healthy, and no additional signs were observed. The baby's mother reported only one other isolated similar episode of about the same duration occurring at home when the baby was lying naked on the changing table. HP is a rare event that consists of a sudden unilateral transient change in skin colour with a sharp demarcation along the body midline, resulting in two different body colours.1 HP usually occurs between the 3rd and 4th day of life, and typically appears when the baby is lying on the side and may last from 30 s up to 20 min. It can be a single event or it can be recurrent. Newborns can experience several episodes in just a few days.2 Pathophysiology of HP is still not completely clear although there is evidence to support a sympathetic autonomic dysfunction, probably because of hypothalamic immaturity in the newborn.2 HP represents a benign condition although it has also been reported in the context of hypoxia and as an epiphenomenon of central nervous system disorders such as meningitis, hypothalamic and brain stem lesions or sympathetic nervous system lesions. Exacerbation has been described in patients receiving treatment with prostaglandin E1.1, 3 While the clinical characteristics of HP make it easily distinguishable, a differential diagnosis should include infectious neonatal skin rashes, such as parechovirus, herpes virus and candida infection, neonatal lupus erythematosus and capillary malformations such as those in the PROS spectrum and cutis marmorata telangiectatica congenita. HP can be a manifestation of the rare disorder paroxysmal extreme pain disorder, part of SCN9A neuropathic pain syndromes, a group of sodium channelopathies where systemic symptoms such as tonic nonepileptic attacks and syncope with bradycardia are associated with the transient skin colour change.4 HP is a benign and self-resolving phenomenon. As mentioned, only in rare circumstances HP is a manifestation of central nervous system disorders in association with other signs and symptoms and never presenting as the sole clue of such conditions.5 The recognition of the phenomenon is therefore important since, while being certainly peculiar, it does not require further investigations or therapeutic measures. Alice Nadia Rossi wrote the first draft of the manuscript and adjusted it according to the comments of the other authors. Francesco Paolo Salamone collected data and clinical images and helped writing the manuscript. Martina Mussi participated in data collection. Marco Adriano Chessa participated in the revision of the manuscript. Iria Neri carried out the final revision of the manuscript before submission. All of the authors participated in the preparation of the manuscript. There are no prior publications or submissions with any overlapping information, including studies and patients. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. The authors declare no conflicts of interest. All patients in this manuscript have given written informed consent for participation in the study and the use of their de-identified, anonymized, aggregated data and their case details (including photographs) for publication. Data sharing is not applicable to this article as no new data were created or analysed in this study.