Imaging of the head and neck for melanoma is usually performed as part of staging for metastatic lymph nodes and intracranial metastases. If the primary site is the skin of the scalp, face, or neck, imaging can be performed to determine depth of invasion. This topic is dealt with in detail in the chapter on skin cancers. The lymphatic drainage of primary melanoma of the skin tends to follow the expected pattern associated with squamous cell cancer, that is, parotid and facial nodes, as well as occipital and level 1 nodes, followed by cervical chain nodes. However, there are reports of more variability of lymphatic drainage with melanoma.^1,2,3 Therefore, bilateral nodes at all levels must be examined carefully on the scans. The sentinel node is typically mapped with nuclear medicine lymphoscintigraphy (Fig. 24-7) and has prognostic value.⁴ An FDG-PET scan is usually performed for initial staging to determine distant spread of disease. FDG-PET typically shows marked radiotracer uptake,⁵ but there is variability of uptake perhaps related to the histologic type of melanoma⁶ (Figs. 24-7 and 24-8). FDG-PET is commonly used in surveillance scanning following treatment.

Melanoma lymph node metastases tend to be quite aggressive in appearance. There is often a solid enhancing portion with areas of necrosis (Fig. 24-9). Extracapsular spread is common. Early necrosis is often present, and, occasionally, almost purely necrotic nodes will be encountered (Fig. 24-10).

Extranodal sites of melanoma in the head and neck are rare, but can occur in the thyroid gland (Fig. 24-11) and mucosal surfaces of the head and neck. The sinonasal region and oral cavity are the most common sites of involvement along the
aerodigestive tract (see Fig. 24-8). Outcome remains poor, perhaps because of the dual lymphatic and hematogenous metastasis pattern, and the frequency of distant failure despite local/regional control.^7,8,9 Orbital melanoma is discussed separately in the chapter on cancer of the orbit.