NEW YORK – Nail discoloration, in all its variety, has a wide differential. And while that differential narrows when a patient presents with concerns about nails with red discoloration, there’s still a long list of diagnoses to consider.
During a nail-focused session at the American Academy of Dermatology summer meeting, Shari Lipner, MD, PhD, took attendees through a presentation-based approach that gets to the root etiology of erythronychia and guides diagnosis and treatment options.
“However, regardless of the etiology, erythronychia shares a common pathogenesis,” said Dr. Lipner, a dermatologist at New York–Presbyterian Hospital and Weil Cornell Medicine. The process begins in the distal nail matrix, resulting in a thin long strip of ventral nail becoming discolored, with the nail bed filling in the concavity. The engorged nail bed also makes the affected nail unit prone to splinter hemorrhages, and the thinned, transparent nail makes the erythema more visible, she explained.
Polydactylous longitudinal erythronychia
For erythronychia affecting several nails, onychotillomania is among the possible causes. This condition “often goes hand in hand with onychophagia,” and trichotillomania, skin-picking, or other self-mutilating disorders may also be present, she said. In both the adult and pediatric population, onychotillomania can accompany psychiatric disorders, including depression and obsessive-compulsive disorder, and may be associated with suicidal ideation, she added.
When onychotillomania is the cause, erythronychia may be accompanied by paronychia, and patients will often have a shortened nail bed and an atrophic nail plate. Dorsal pterygium may also be present.
Dermoscopy can provide some clues that onychotillomania is the culprit, said Dr. Lipner, citing a study that looked at dermoscopic images of 36 cases, which found scales in 94%, absence of the nail plate in 83%, and characteristic wavy lines in 69% (J Am Acad Dermatol. 2018 Oct;79[4]:702-5). Other frequent dermoscopy findings included hemorrhages (64%), crusts (61%), nail bed pigmentation (47%), and speckled dots (39%).
Lichen planus can also affect the nails, with erythronychia among its manifestations, she noted. Though lichen planus is thought of as a disease of middle or older age, usually affecting those aged 50-70 years, “15% of those affected are less than 20 years old,” she said.
The erythronychia of lichen planus is often accompanied by longitudinal riding, splitting, and atrophy of the nail plate, she said. Pterygium can also be present, representing a scar in the nail matrix. Dermatopathology will reveal a patchy, bandlike lichenoid infiltrate, with variable sawtooth hypergranulosis and hyperplasia.
“There’s not much evidence about how to treat lichen planus of the nails,” noted Dr. Lipner. Options can include intralesional corticosteroid injections at the nail matrix, topical corticosteroids, oral methotrexate, and retinoids.
Darier disease, an inherited condition caused by mutations in ATP2A2, has both skin and nail manifestations. Characteristic skin signs include hyperkeratotic papules, cobblestone papules, and palmar pits, she said. When nails are affected – as they are in up to 95% of Darier disease patients – they can have a characteristic “candy cane” appearance, with bands of longitudinal erythronychia alternating with normal-colored nail. The nails can also have V-shaped notching, she added.
Patients with systemic lupus erythematosus can also have longitudinal erythronychia; here, dermoscopy will show the characteristic prominent capillary loops in the proximal nail folds, she said.
Foreign substances such as nail polish and dyes, when they’re the source of erythronychia in one or several nails, can usually be wiped off with alcohol or acetone; also, “the proximal margin of discoloration will follow the same pattern as the nail fold,” said Dr. Lipner.