Postbiopsy Pigmentation is Prognostic in Head and Neck Melanoma.

Purpose: To assess postbiopsy pigmentation (PBP) as a prognostic feature in patients with cutaneous head and neck (H&N) melanoma.

Methods: Retrospective review of patients undergoing sentinel lymph node biopsy (SLNB) for H&N melanoma (1998-2018). PBP was defined as visible remaining pigment at the scar or biopsy site that was documented on physical exam by both a medical oncologist and a surgeon at initial consultation. Variables associated with disease-free survival (DFS) and overall survival (OS) were analyzed using multivariable Cox proportional hazards models.

Results: Among 300 patients, 34.3% (n = 103) had PBP and 44.7% (n = 134) had microscopic residual disease on final pathology after wide local excision. Prognostic factors associated with DFS included advanced age, tumor depth, ulceration, PBP, and positive SLNB (p < 0.05). Patients with PBP fared worse than their counterparts without PBP in 5-year DFS [44.1% (31.1-56.3%) vs. 73.0% (64.1-80.0%); p < 0.001] and 5-year OS [65.0% (50.0-76.6%) vs. 83.6% (75.7-89.2%); p = 0.005]. After multivariable adjustment, PBP remained associated with shorter DFS [hazard ratio (HR) 1.72, 95% confidence interval (CI) 1.01-2.93; p = 0.047], but was not prognostic of OS.

Conclusions: In patients with H&N melanoma, PBP is associated with significantly shorter DFS. Patients with PBP may warrant greater consideration for SLNB and closer postoperative surveillance.