Monodactylous Longitudinal Melanonychia: A Sign of Bowen's Disease in Skin of Color.

Introduction Monodactylous longitudinal melanonychia (LM) may represent both benign and malignant dermatologic disorders. However, squamous cell carcinoma in situ (SCCis) is not commonly considered in this setting. Case presentation In this report, we present 2 cases of SCCis of the nail matrix in patients with skin of color who presented with monodactylous LM involving the lateral aspect of the nail. Conclusion These cases suggest that SCCis should be included in the differential diagnosis for monodactylous LM, especially when involving the lateral nail plate in darker skin.