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[472] Clinical Significance of Morphometric Measurements of Melanoma Metastatic to Single Sentinel Lymph Nodes

R Yaar, A Page, A Hestley, K Delman, GW Carlson, C Cohen. Emory University, Atlanta, GA

Background: Sentinel lymph node (SLN) biopsy is a common procedure for staging patients with melanoma of >1 mm thickness. Immunohistochemistry for S100 protein and HMB45 facilitates examination of SLNs by highlighting small deposits of melanoma. Previous studies have suggested that certain morphometric features of metastatic deposits may predict clinical behavior of the disease and help guide treatment. The goal of this study is to identify a relationship between the morphometric characteristics of metastatic melanoma in single SLNs with disease relapse.
Design: S100 protein and HMB45 immunostained sections of SLNs from 122 patients with melanoma and a single, positive SLN were reviewed. Eleven morphometric characteristics of metastatic deposits were each scored by two pathologists and compared to clinical data for relapse.
Results: Deposits stained positively for S100 protein and HMB45 in 98% and 84% of cases, respectively. There were 41 (34%) relapses of any type and 37 (31%) distant relapses, which excludes cases with local relapse. Univariate analysis reveals that percentage of lymph node replacement by melanoma (<1%, <5%), depth of melanoma deposits relative to the lymph node capsule, and intraparenchymal deposits in the absence of subcapsular deposits, demonstrate a statistically significant correlation with relapse. In multivariate analysis, head and neck primary site is associated with an increase in relapse of any type (76% relapse rate, p=0.001), but morphometric measurements fall out of significance. When only distant relapse is considered, multivariate analysis demonstrates that small overall volume of melanoma deposits in a SLN (<5%) are associated with a decreased incidence of relapse (20% relapse rate, p=0.02) and intraparenchymal deposits in the absence of subcapsular deposits are associated with an increased incidence of relapse (67% relapse rate, p=0.02).
Conclusions: In addition to primary site, morphometric measurements of metastatic deposits in SLNs are associated with clinical relapse. Small volumes (<5%) of melanoma and intraparenchymal deposits in the absence of subcapsular deposits are independent indicators of the incidence of distant relapse. These findings may help predict clinical behavior and have therapeutic implications in patients with single positive SLNs.
Category: Dermatopathology

Monday, March 3, 2008

Poster # 82, Monday Morning