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Page 6 of 14 Woods et al. J Cancer Metastasis Treat 2022;8:22 https://dx.doi.org/10.20517/2394-4722.2022.28

the primary tumor site is associated with a high risk for parotid spread, either parotidectomy can be carried
out alongside the neck dissection, or adjuvant radiation can be used to treat the parotid. It is also important
to resect the external jugular lymphatics in these cases and level V for tumors based posteriorly [2,64,72,79] .

For patients with parotid nodal metastases who are otherwise clinically node-negative, additional elective
selective neck dissection would include levels I-III for anterior facial primaries, levels II-III for anterior scalp
and external ear primaries, and levels II-V including postauricular and suboccipital nodes for posterior
scalp and neck primaries .
[79]

Although it has been suggested that total parotidectomy be considered when positive parotid nodes are
identified [69,80,81] , there is potential for higher complications from this, and so it may only be beneficial in
cases with definite deep lobe involvement [56,82,83] . Radical or extended radical parotidectomy may be
[81]
necessary depending on the involvement of adjacent structures . When metastatic cutaneous SCC is
adherent to the temporal bone, some form of lateral temporal bone surgery should be carried out , which
[84]
[85]
may be aggressive and require adjuvant radiation .
Trigeminal, facial and cervical plexus nerves can be at risk of cutaneous malignancy, usually by the primary
tumor itself, but also potentially by regional nodal disease, particularly if extranodal extension is
present [69,86] . This is usually due to direct invasion by nodal disease, but can also be due to perineural spread,
and the parotid gland is more likely involved than the neck. The likelihood of nerve sacrifice is highest in
patients with nodal disease within the body of the parotid gland and when the primary tumor itself
demonstrates perineural invasion . For patients with clinical perineural invasion, available evidence
[87]
suggests that survival is improved by surgical resection if feasible, followed by postoperative radiation [88-91] .
Facial nerve function is an important outcome for patients with cancer of the parotid and temporal bone
region , and ideally, it should only be sacrificed when directly compromised by disease [69,82] . If oncologic
[92]
resection is not possible without sacrificing the nerve, it may require partial or complete resection even if it
is functioning preoperatively. For example, radical resection to ensure clear margins may be necessary for
tumors at the stylomastoid foramen even when the nerve is clinically intact , but efforts should be made to
[84]
preserve the nerve where possible. Intraoperative frozen section to ensure satisfactory clearance of
perineural disease may potentially remove any individual effect on survival . Parotid nodal disease may
[85]
directly involve the auriculotemporal nerve or spread to it via anastomoses with the facial nerve, with
subsequent spread to the infratemporal fossa and foramen ovale [93-95] , in which case partial mandibular
resection may be needed to access the infratemporal fossa.

Merkel cell carcinoma
Status of spread to the lymph nodes is the most important predictor of survival in MCC. Survival has been
reported at 52% for MCC with metastasis to regional nodes, compared to 71% in cases without
metastasis . As micrometastasis is common, and independent of size or depth, sentinel lymph node biopsy
[96]
is recommended for all patients with MCC and is included in the AJCC 8th edition staging system . When
[97]
disease is identified in sentinel nodes, lymph node dissection is suggested, although there are no prospective
studies demonstrating its benefit, and so radiation may be an alternative [96,98] .

Basal cell carcinoma
Regional lymph node metastasis from BCC is exceedingly rare but portends a poorer prognosis than
localized disease . Due to its rarity, no guidelines are established. However, treatment has typically been
[35]
with therapeutic neck dissection and possible adjuvant radiation.