Subungual blue nevus.

Junctional or compound melanocytic nevus and melanoma may involve the nail apparatus and are usually discussed in the differential diagnosis of nail pigmentation. Blue nevus has been very rarely reported in this location. We report the second clinicopathologic study of a subungual blue nevus.

Dermoscopic examination of nail pigmentation.

Background: Diagnosis of longitudinal melanonychia is usually difficult, and neither a single clinical criterion nor a combination of symptoms currently can be used to clearly distinguish malignant from benign bandlike pigmented nail lesions. Biopsy is painful and often leaves definitive dystrophic scars.

Objectives: To describe and evaluate dermoscopic patterns associated with longitudinal nail pigmentation.