Background: Longitudinal erythronychia (LE) is an underappreciated and understudied clinical diagnosis. The rates of malignancy and prevalence within the differential diagnosis are not well-established.
Objective: To examine the prevalence of biopsy-proven diagnoses in patients presenting with LE.
Methods: Retrospective single-center study of 65 consecutive patients undergoing biopsy of LE.
Results: Malignancy was identified in only 3 of 65 cases (in situ carcinoma in 2 and melanoma in 1). Onychopapilloma was the most common diagnosis in cases of localized LE. Lichen planus was the most common diagnosis in cases of polydactylous (generalized) LE.
Conclusion: Longitudinal erythronychia is not a rare clinical finding. The differential diagnosis includes neoplasms, inflammatory conditions, infectious conditions, and scar. Clinicopathologic correlation is required to make the diagnosis in many cases. Malignancy is uncommon, but not rare, with squamous cell carcinoma in situ representing the most common malignancy.