Original StudyReticulin and NM23 Staining in the Interpretation of Lymph Nodal Nevus RestsKanner, William A. MD*; Barry, Catherine I. DO†; Smart, Chandra N. MD‡; Frishberg, David P. MD†; Binder, Scott W. MD‡; Wick, Mark R. MD* Author Information *Department of Pathology, University of Virginia Health System, Charlottesville, VA †Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, CA ‡Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, CA. Reprints: William A. Kanner, MD, Department of Pathology, University of Virginia Health System, PO Box 800214, 1215 Lee Street, Office 3036, Charlottesville, VA 22908-0214 (e-mail: [email protected]). Presented at the 2010 USCAP Annual Meeting, Poster Presentation, Washington, DC, March 20–26, 2010. The authors declare no conflicts of interest. The American Journal of Dermatopathology: June 2013 - Volume 35 - Issue 4 - p 452-457 doi: 10.1097/DAD.0b013e318272c104 Buy Metrics Abstract Melanocytic nevus rests in lymph nodes are a known diagnostic challenge, especially in patients with a history of melanoma. Reticulin and NM23 have been studied in this context. The pattern of reticulin staining in melanomas surrounds groups/nests of melanocytes but individual cells in benign nevi. NM23, a metastasis-suppressor gene, has an association with metastatic potential in melanomas and some carcinomas. Twenty-eight cases (14 cases of metastatic melanoma to lymph nodes and 14 cases of lymph node nevus rests, all confirmed with Melan-A staining) were stained with reticulin and NM23. The pattern of reticulin staining was reported as surrounding groups if staining was noted in approximately 5–10 melanocytes in greater than 50% of the lesion but was otherwise reported as surrounding individual melanocytes. Cytoplasmic staining was considered to represent reactivity for NM23. Reticulin staining around groups of melanocytes was identified in all 14 cases of metastatic melanoma. Regarding nodal nevus rest cases, 12 of 14 cases (86%) demonstrated staining around individual melanocytes, whereas in 2 cases, reticulin surrounded melanocytic groups. NM23 staining was equivocal in all cases. Reticulin staining reliably invests groups of melanocytes in cases of metastatic melanoma, whereas in nodal nevus rests, it predominantly surrounds individual melanocytes. NM23 demonstrated no discriminatory value in this analysis. In cases in which a collection of melanocytes is present within a lymph node, reticulin deposition around individual melanocytes supports a diagnosis of lymph nodal nevus rest. © 2013 by Lippincott Williams & Wilkins.