Capsular Melanocytic Nevus A Potential Diagnostic Pitfall in Intraoperative Sentinel Lymph Node Evaluation for Metastatic Melanoma

摘要

We report a case of capsular melanocytic nevus morphologically mimicking metastatic melanoma during intraoperative imprint cytology analysis of sentinel lymph nodes for metastatic melanoma. The benign nevus cells stained positively for S-100 protein like melanoma, but were negative for HMB-45, lacked cytologic atypia, and had a distinct intracapsular location, unlike melanoma. These features are useful in distinguishing capsular melanocytic nevi from metastatic melanoma. As a false-positive diagnosis intraoperatively may result in unnecessary lymphadenec-tomy, pathologists must be aware of capsular melanocytic nevi as potential false-positive interpretation.