Hypothesis: Patients with melanoma and histologically negative sentinel lymph nodes identified by lymphatic mapping have a very good prognosis.
Design: Cohort study with follow-up information obtained from medical records and telephone interviews.
Setting and patients: Of all patients with cutaneous melanoma who underwent intraoperative sentinel lymph node mapping between November 15, 1993, and April 18, 1997, at the Massachusetts General Hospital, Boston, 89 were found to have no evidence of melanoma in their sentinel nodes. Forty-six lesions (51%) were on an extremity and 44 (49%) were of axial location. The median tumor thickness was 1.8 mm (range, 0.36-12.0 mm) and 11 tumors (12%) were ulcerated.
Interventions: Patients underwent intraoperative sentinel lymph node mapping with lymphazurin and radiolabeled sulfur colloid. Sentinel lymph nodes were analyzed by standard hematoxylin-eosin staining. Only 2 patients received adjuvant therapy following wide excision of the primary lesion.
Main outcome measures: Site of initial recurrence and time to initial recurrence.
Results: The median follow-up for all patients was 23 months (range, 2-54 months). Eleven patients (12%) developed melanoma recurrences, and 78 (88%) patients remain disease free. Regional lymph nodes were the initial site of recurrence in 7 (8%) of 89 patients, and 7 (7%) of 106 mapped basins. Four patients had recurrence without involvement of regional lymph nodes: 2 with distant metastases and 2 with in transit metastases. The median time to recurrence was 12 months (range, 2-35 months). Sentinel lymph nodes were reanalyzed using serial sections and immunoperoxidase stains in 7 patients with recurrence and metastatic melanoma was identified in 3 (43%).
Conclusions: The risk for melanoma recurrence is relatively low in patients with histologically negative sentinel nodes identified by lymphatic mapping. Longer follow-up will improve our understanding of the prognostic value of this procedure.