Patterns of node mapping differ for axial and extremity primary cutaneous melanoma: A case for a more selective use of pre-operative imaging.

PURPOSE: Preoperative lymphoscintigraphy for sentinel lymph node mapping in melanoma improves the ability to locate nodes. However, it still remains unclear whether this step is required for all patients.

METHODS

Patients diagnosed with cutaneous melanoma from 1996 to 2012 were identified. Exclusion criteria were in situ disease, metastatic disease, or no SLN biopsy.

RESULTS

214 patients were evaluated. Median age was 57 years, the majority were male (59.8%), white (97.2%), and stage I (60.7%). SLN revealed metastatic disease in 14.5% of patients. The most common primary site was the trunk (43.4%) followed by head and neck (21%), upper extremity (19.2%), and lower extremity (16.4%). Multiple lymphatic basins were most common for head and neck lesions (66.7%) followed by those on the trunk (28.8%), with fewer identified when lower (11.4%), and upper extremities were involved (4.2%). When comparison was restricted to extremity vs. axial, a single basin was noted in 94.5% vs. 59.9% of patients, p < 0.0001. For all extremity lesions the SLN was located in the primary basin. Additional sites included in-transit (popliteal) and second tier basins. The only melanomas with bilateral or contralateral SLN were axial melanomas.

CONCLUSIONS

Patients with axial melanomas benefit most from lymphoscintigraphy. This step may not be required for extremity melanoma.