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Woods et al. J Cancer Metastasis Treat 2022;8:22 https://dx.doi.org/10.20517/2394-4722.2022.28 Page 3 of 14

Figure 2. Patterns of metastatic spread to lateral neck lymph nodes from non-melanoma skin cancer of the head and neck.

histologic type, degree of differentiation, perineural invasion, and immunosuppression [15-18] .
Immunocompromise is a significant independent risk factor for the aggressive behavior of metastatic
cutaneous SCC to the neck [19,20] . Presence of disease in regional nodes from cutaneous SCC has been
associated with five-year survival rates ranging from 35%-70%, depending on tumor stage, surgery, and
adjuvant treatment [14,16,21-25] .

Merkel cell carcinoma
MCC is a neuroendocrine carcinoma with a high propensity for regional spread of over 50% and, even in
cases without clinical evidence of lymph node metastasis, the rate of nodal micrometastasis on sentinel
[26]
lymph node biopsy can be 30%-38% . MCC of unknown primary occurs in 5%-25% of cases and carries
improved survival and different tumor characteristics compared to tumors with presence of a primary [27-30] .
[31]
Increasing nodal disease burden has been suggested as a prognosticator in MCC .

Basal cell carcinoma
[32]
While BCC is the most common primary cutaneous malignancy found in the head and neck , it rarely
metastasizes to lymph nodes. Rates of nodal disease from primary BCC are reported between 0.0028% to
[33]
0.55% . Regional spread from BCC is associated with male gender, fair skin, and history of radiation, as
well as primary tumor factors such as increased size, deeper invasion, perineural invasion, basosquamous
histology, and primary site in the head and neck [33-36] .

Adnexal tumors
Cutaneous adnexal tumors, including those involving hair follicles, sweat ducts, ceruminous glands,
sebaceous glands, apocrine glands, and eccrine glands, may occur sporadically or as part of genetic
syndromes. Rates of regional spread are uncertain due to the rare and heterogeneous nature of these
tumors; however, the presence of lymph node metastases portends significantly worse overall survival . It
[37]
has been suggested that these tumors are more likely to demonstrate nodal involvement with aggressive
local histology, and that lymphatic disease in early-stage tumors is rare [38,39] , but high rates of up to 89% have
also been reported .
[40]