Patterns of nail matrix and bed of longitudinal melanonychia by intraoperative dermatoscopy

Background The dermatoscopic examination of the nail plate has been recently introduced for the evaluation of pigmented nail lesions. There is, however, no evidence that this technique improves diagnostic accuracy of in situ melanoma. Objective To establish and validate patterns for intraoperative dermatoscopy of the nail matrix. Methods Intraoperative nail matrix dermatoscopy was performed in 100 consecutive bands of longitudinal melanonychia that were excised and submitted to histopathologic examination. Results We identified 4 dermatoscopic patterns: regular gray pattern (hypermelanosis), regular brown pattern (benign melanocytic hyperplasia), regular brown pattern with globules or blotch (melanocytic nevi), and irregular pattern (melanoma). Limitations Nail matrix dermatoscopy is an invasive procedure that can not routinely be performed in all cases of melanonychia. Conclusion The patterns described present high sensitivity and specificity for intraoperative differential diagnosis of pigmented nail lesions.