A false-negative sentinel lymph node in the parotid gland of a melanoma patient: a new algorithm for SLN biopsy in the parotid gland

The sentinel lymph node (SLN) is the first node in the lymphatic basin to be affected by metastatic tumor cells from a primary lesion. It provides a way to avoid elective neck dissection in a case in which there is no metastasis to the SLN. However, identification and excision of the SLN may be difficult due to the shine-through phenomenon, as the SLN in the parotid gland is either located close to the primary lesion or, in many cases, the lymph node of the parotid gland is small and covered by fibrous capsula. When we conducted an SLN biopsy on a 68-year-old male patient with malignant melanoma of the cheeks, the metastasis to the node of the parotid gland identified as the SLN was negative; however, 1 year later, the melanoma recurred on the lymph node of the parotid gland, or in other words, we experienced a false-negative SLN. SLN biopsy in the parotid gland is difficult because the lymph node is small and covered by fibrous capsula. We may consider a total or partial resection of the superficial lobe of the parotid gland, particularly when identification of an SLN in the parotid gland is difficult. Therefore, we propose a new algorithm for SLN biopsy in the parotid gland.