Sentinel lymph node biopsy (SLNB) is a key staging tool in head and neck (H&N) melanoma. The significance of preoperative SLN non-visualisation on preoperative imaging remains unclear. This study evaluated the prevalence, characteristics, and outcomes associated with preoperative SLN non-visualisation in H&N melanoma.

A 17 year retrospective review of 400 patients undergoing wide local excision for H&N melanoma was performed. Melanoma sites were identified using photography, and SLN visualisation assessed with lymphoscintigraphy and SPECT-CT.

SLN visualisation was absent in 35 patients (8.8%). Among these, melanoma recurrence occurred in 11 (31.4%). Absent drainage was substage-dependent, occurring more frequently in ‘a’ than ‘b’ substages across all T categories (OR = 2.98; p-value = 0.011). Patients with non-visualisation were significantly older than those with successful visualisation (median 76 vs. 65 years; p < 0.001), and non-visualisation varied according to primary anatomical site.