Nailing the Red Streak: Evaluation of Erythronychia and Novel Insights
June 2026
Dr. Adam Rubin presented information about the clinical presentation, histopathology, and differential diagnosis of longitudinal erythronychia. The differential diagnosis of longitudinal erythronychia includes onychopapilloma, nail unit acantholytic dyskeratotic acanthoma, glomus tumor, symplastic glomus tumor, arteriovenous malformation, subungual leiomyoma, amelanotic melanoma, and nail unit squamous cell carcinoma. Polydactylous erythronychia may indicate systemic disease.
Adam Rubin, MD, professor of dermatology at the New York University Grossman School of Medicine and director of the Section of Dermatopathology, Ronald O. Perelman Department of Dermatology at NYU Langone Health
First, Rubin discussed the clinical presentation and biopsy technique of onychopapilloma, the most common diagnosis when patients present with longitudinal erythronychia. Onychopapillomas may appear as erythronychia, leukonychia (a white line), and melanonychia. Distal hyperkeratosis and V nicking are common features. On onychoscopy (nail dermoscopy), onychopapillomas may appear with splinter hemorrhage, hyperkeratosis, and onycholysis. This may be difficult to see if patients have manipulated the nail.
The surgical approach for suspected onychopapilloma differs from melanonychia because the diagnostic histopathologic features are found in the nail bed, distal nail matrix, and hyponychium. A longitudinal excision or longitudinal superficial shave is necessary for accurate diagnosis. Rubin urged dermatologists to submit clinical photos with biopsy specimens. Head-on examination and photographs can help define the lesion. Diagnostic histopathologic features include matrix metaplasia in the nail bed, multinucleate keratinocytes, and stacked parakeratosis emanating from the hyponychium.
Second, Rubin described clinical cases demonstrating other diagnoses of longitudinal erythronychia and diffuse erythronychia, including malignant onychopapilloma, glomus tumor, nail unit arteriovenous malformation, amelanotic melanoma, nail unit squamous cell carcinoma, and nail unit amyloidoma.
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