A Solitary Melanoma Metastasis Confined to the Submandibular Gland

Malignant melanoma is a type of cancer that most commonly originates from the skin, less frequently from mucosal surfaces, the eye, or meninges [Annu Rev Pathol. 2014;9(1):239-71]. In 2019, this type of malignancy was the third most frequent cancer to be diagnosed in males and the fifth most in females according to the American Cancer Society and the National Cancer Institute [CA Cancer J Clin. 2019;69(5):363-85]. The majority of the malignant melanomas in the head and neck region (85-90%) are cutaneous lesions, most often arising in the skin of the face [Head Neck. 2016;38:147-155]. In sharp contrast are the histological findings of metastatic melanoma with an unknown primary site: they are much more scarce and histologically difficult to diagnose. The literature is limited to case studies or small cohorts. In 2-6% of all patients suffering from metastatic melanoma, after clinical examination of the skin and mucosa, imaging, and other diagnostic examination, a primary tumor cannot be found [Eur J Cancer. 2004;40(9):1454-5]. A very small subgroup (0.5%) presents with a single focus of melanoma within the dermis or subcutaneous tissues [Arch Dermatol. 2000;136(11):1397-9]. We hereby report a case in this subgroup of a solitary melanoma metastasis found in the submandibular gland in a 59-year-old male. The tumor was discovered incidentally after surgical excision of this gland because of nodular enlargement.