Nail Unit Arteriovenous Hemangioma Presenting as Longitudinal Erythronychia.

Introduction: Localized longitudinal erythronychia is defined as a single nail with a longitudinal red band extending the length of a nail plate. It has a broad differential of benign and malignant etiologies, and is rarely due to benign vascular proliferations.
Case Presentation: We present a unique case of nail unit arteriovenous hemangioma presenting as longitudinal erythronychia of the left thumbnail in a 76-year-old male. The band was 6 mm and encompassed over 40% of the surface area of the nail plate. Dermoscopy showed red bands that were regular in terms of color, but not thickness or spacing. Due to concern for an amelanotic melanoma, a longitudinal excision was performed. Histopathology was consistent with a diagnosis of nail unit arteriovenous hemangioma.
Conclusion: Arteriovenous hemangiomas were rarely present in the nail unit. They can be present as a blue or red nodule/macule, or as longitudinal erythronychia. Diagnosis often requires an excisional biopsy, with histopathology notable for a proliferation of multiple thick- and thin-walled vascular structures lined by a flattened endothelium. Our case emphasizes the need to consider vascular proliferations, such as arteriovenous hemangioma, in the differential diagnosis of longitudinal erythronychia.
Competing Interests: Authors J.K.H. and C.M.M. have no conflicts of interest to declare. Author S.R.L. has served as a consultant for Hoth Therapeutics, Ortho Dermatologics, BelleTorus Corporation, and Moberg Pharmaceuticals.
(© 2023 The Author(s). Published by S. Karger AG, Basel.)