Detection of microscopic melanoma metastases in sentinel lymph nodes

BACKGROUND. Sentinel lymph node biopsy following radioisotope labeling is a recently developed, minimally invasive surgical staging procedure used in the management of primary cutaneous malignant melanoma. If histologic analy sis reveals melanoma metastasis in the sentinel lymph node, completion lymp hadenectomy is performed and adjuvant therapy considered. The routine patho logic assessment of the sentinel lymph node consists of bisecting the lymph node along its long axis and histologic examination of one hematoxylin and eosin-stained section of each cut surface. METHODS. In this study, the authors reexamined 235 sentinel lymph nodes rep orted as negative for melanoma metastasis following routine histologic exam ination, from 94 patients with American Joint Committee on Cancer (AJCC) St age I and II cutaneous melanoma. RESULTS. Deeper sections into the lymph node and immunohistochemical stains with antibodies to S-100, HMB-45, NK1C3, and MART-1 led to the identificat ion of microscopic metastases in 11 sentinel lymph nodes from 11 patients a nd capsular nevi in 9 sentinel lymph nodes from 8 patients. CONCLUSIONS. Deeper serial sections and immunohistochemical stains detected microscopic metastases in approximately 12% of cases that would be reporte d as negative for metastasis by routine pathologic analysis. These techniqu es also allowed for the identification of capsular melanocytic nevi in the sentinel lymph nodes of 9% of patients. [See editorial on pages 551-2, this issue.] Cancer 1999;86:617-27. (C) 1999 American Cancer Society.