D2-40 lymphatic marker for detecting lymphatic invasion in thin to intermediate thickness melanomas: Association with sentinel lymph node status and prognostic value - A retrospective case study

Background: Sentinel lymph node (SLN) status is the greatest prognostic factor of morbidity in melanoma. D2-40 antibody specifically marks lymphatic endothelium and has been used for identifying lymphatic invasion (LI) in multiple cancers. Objective: We sought to determine the relationship between melanoma lymphatic invasion (as detected using D2-40 on primary melanoma biopsies/excisions) and the presence or absence of melanoma in subsequent SLN biopsy. Methods: We retrospectively evaluated LI using D2-40 on primary biopsies/excisions from patients with thin to intermediate thickness (Breslow thickness: ≤2.0 mm) melanomas, who underwent lymphatic mapping and SLN biopsy, and whose SLN status was known. Sixty-four cases met the criteria and were available for analysis. We analyzed patient age, patient sex, mitotic rate, ulceration, tumor depth, and D2-40 detected LI as predictors of SLN status. Results: Lymphatic invasion detection increased from 3.1% using hematoxylin and eosin only to 21.9% using D2-40. Twelve of 14 patients with D2-40 LI were SLN positive (positive predictive value, 85.7%). D2-40 LI was detected in the primary biopsy specimen of 12 of 18 patients with a positive SLN (sensitivity 66.7%). Of 50 patients without D2-40 LI, 44 were SLN negative (negative predictive value, 88.0%). Of 46 SLN-negative patients, 44 did not have D2-40 LI (specificity, 95.7%). Limitations: Results are retrospective and limited to SLN biopsy performed at one institution. Conclusions: On univariate and multivariate analysis, D2-40-detected LI was the most significant predictor of SLN status. D2-40 antibody staining to detect lymphatic invasion should be incorporated in routine melanoma biopsy evaluation.