Lymphoscintigraphy for malignant melanoma. Surgical considerations.

Lymphoscintigraphy using technetium-99m atimony sulfur colloid was performed in 22 patients with melanoma referred to Duke University Comprehensive Cancer Center in an attempt to identify patterns of regional lymphatic drainage. Scans from six patients revealed lower extremity lesions with three located below the knee, one in the popliteal space, and two others proximal to the knee joint. Despite the location of the primary, all scans but one showed initial drainage to the inguinal nodes bypassing the popliteal lymph node group. Of the three patients who had primary melanoma of the posterior scalp, the lymphatic drainage was directed to the posterior cervical nodes. No drainage to the parotid nodes or anterior neck nodes was visualized. The knowledge gained from lymphoscintigraphy resulted in posterior neck dissections instead of the standard anterior neck dissection and superficial parotidectomy. In areas of ambiguous lymphatic drainage from the trunk, radiocolloid scanning can identify areas at risk for developing metastatic disease. Six lesions within 5 cm of the midline demonstrated bilateral axillary or groin drainage in 83 per cent of the patients. For two lesions near Sappey's line colloidal uptake to the ipsilateral axilla and groin was the rule. After a 3-year follow-up, during which time 70 to 90 per cent of lymph node metastases are predicted to occur, no nodal metastases were ever documented in areas that did not show colloidal uptake. No correlation was found between amount of radiolabel in positive compared to negative nodes, although those nodes that were completely replaced by tumor contained no 99mTc activity and were negative on scanning.(ABSTRACT TRUNCATED AT 250 WORDS)