Sentinel node biopsy is a means of identifying nodal involvement in melanoma and lymphoscintigraphy identifies unpredictable sites of melanoma sentinel nodes in up to 25% of cases. Whilst there is a dearth of recent publications in this area, it nevertheless remains an interesting observation that unpredictable sites of sentinel nodes are so common as to be accepted as normal. This study was performed to determine if this high rate of unpredictable lymphatic drainage was reflected in clinical practice, where therapeutic lymph node dissections were performed for pathologically confirmed regional disease.
Methods: Patients undergoing regional lymph node dissections for histologically proven malignant melanoma were identified from a computer database. Patient details were analysed from case records.
Results: Two hundred and forty-three case records were examined and 237 were suitable for analysis. The site of the primary was the head and neck in 50 (21%), trunk in 73 (31%), upper limb in 27 (11%) and lower limb in 87 (37%). In 15 cases (6%), the first site of regional disease was unpredictable. In these 15 cases, the site of the primary was the head and neck in two, trunk in 11, upper limb in one and lower limb in one. In 37 cases (16%), a subsequent site of nodal recurrence was unpredictable. Clinicians should be aware that patients with melanomas, particularly of the trunk, especially those in whom a therapeutic nodal dissection has been performed, may have nodal disease at unpredictable sites. However, unexpected sites of regional disease are not as common as sentinel node biopsy would suggest. Guidelines for lymph node examination in cutaneous melanoma are suggested based on these findings.