Frequency and implications of occipital and posterior auricular sentinel lymph nodes in scalp melanoma.

Background: Patients with scalp melanoma have poor oncologic outcomes compared with those with other cutaneous sites. Sentinel lymph node (SLN) biopsy provides prognostic information but is challenging in the head and neck. We explore the anatomic distribution of scalp melanoma and describe the most common sites of SLN drainage and of SLN metastatic disease.

Methods: Retrospective review of scalp melanoma patients who underwent SLN biopsy. Melanoma location was classified as frontal, coronal apex, coronal temporal, or posterior scalp. SLN location was classified by lymph node level and region.

Results: We identified 128 patients with scalp melanoma. The most common primary tumor location was the posterior scalp (43%) and the most frequent SLN drainage site was the level 2 lymph node basin (48%). Total 31 patients (24%) had metastatic disease in an SLN. Scalp SLNs, classified as being in the posterior auricular or occipital region, were localized in 26% of patients. For patients in which a scalp SLN was identified, 30% had a positive scalp SLN (n = 10).

Conclusions: Scalp SLNs are frequent drainage sites for scalp melanoma and, when found, have a 30% chance of harboring metastatic disease. Surgeons, radiologists, and pathologists should be vigilant in identifying, removing, and analyzing scalp SLNs.