The Histopathologic Evaluation of Diagnostic Procedures in Nail Melanoma.

INTRODUCTION

The diagnostic delay in nail melanoma (NM) has been repeatedly emphasized. It may be related to both clinical misinterpretations and to errors in the bioptic procedure.

OBJECTIVES

To assess the efficacy of histopathologic examination in different diagnostic biopsies in NM.

METHODS

We retrospectively investigated the diagnostic procedures and histopathologic specimens referred to the Laboratory of Dermatopathology for the clinical suspicion of NM from January 2006 to January 2016.

RESULTS

Eighty-six nail histopathologic specimens were analyzed consisting in 60 longitudinal, 23 punch and 3 tangential biopsies. A diagnosis of NM was performed in 20 cases, benign melanocytic activation in 51 cases and melanocytic nevi in 15 patients. Longitudinal and tangential biopsy were diagnostic in all cases, regardless of the clinical suspicion. Nail matrix punch biopsy instead was not diagnostic in most of the cases (13/23 specimens).

CONCLUSIONS

In the presence of an NM clinical suspicion, longitudinal biopsy is recommended (lateral or median) because it provides exhaustive information on the characteristics of melanocytes morphology and distribution in all the components of the nail unit. Tangential biopsy, recently encouraged by expert authors due to the optimal surgical outcome, in our experience gives incomplete information on tumor extension. Punch matrix biopsy gives limited evidence in the diagnosis of NM.