Our dermatology department recently sponsored a pediatric dermatology lecture series for the pediatric residency program. Within this series, Antonella Tosti, MD, a professor at the University of Miami Health System, Florida, and a renowned expert in nail disorders and allergic contact dermatitis, presented her clinical expertise on the presentation and management of common pediatric nail diseases. This article highlights pearls from her unique and enlightening lecture.
Pearl: Hand-foot-and-mouth disease is a recognized trigger for onychomadesis
An arrest in nail matrix activity is responsible for onychomadesis, or shedding of the nail. Its presentation in children can be further divided based upon the degree of involvement. If a few nails are affected, trauma should be implicated. In contrast, if all nails are involved, a systemic etiology should be suspected. Hand-foot-and-mouth disease (HFMD) has been recognized as a trigger for onychomadesis in school-aged children. Onychomadesis presents with characteristic proximal nail detachment (Figure 1). The association of HFMD with onychomadesis and Beau lines was first reported in 2000. Five patients who resided within close proximity and shared a physician-diagnosed case of HFMD presented with representative nail findings 4 weeks after illness.1 Hypotheses for these changes include viral-induced nail pathology, inflammation from cutaneous lesions of HFMD, and systemic effects from the disease.2 Given the prevalence of HFMD and benign outcome, clinicians should be cognizant of this unique cutaneous manifestation.
Figure 1. Proximal nail detachment of onychomadesis.
Pearl: Management of pediatric melanonychia can take a wait-and-see approach
Melanonychia is the presence of a longitudinal brown-black band extending from the proximal nail fold. The cause of melanonychia can be due to either activation or hyperplasia. Activation is the less common etiology in children; however, if present, activation can be due to Laugier-Hunziker syndrome or trauma such as onychotillomania. Melanonychia in children usually is the result of hyperplasia of melanocytes and can manifest as a lentigo, nevus, or more rarely melanoma. Nail matrix nevi are typically exhibited on the fingernails, particularly the thumb, and frequently are junctional nevi (Figure 2). Spontaneous fading of nevi is expected with time due to decreased melanin production. Therapeutic options for melanonychia include regular clinical monitoring, biopsy, or excision. Dr. Tosti explained that one must be wary when pursuing a biopsy, as it can result in a false-negative finding due to missed pathology. If clinically indicated, a shave biopsy of the nail matrix can be performed to best analyze the lesion. She noted that if more than 3 mm of the matrix is removed, a resultant scar will ensue. Conservative management is recommended given the indolent clinical behavior of the majority of cases of melanonychia in children.3
Figure 2. Melanonychia due to a junctional nevus on the thumb.