Primary melanoma of submandibular gland: case report and literature review of a very rare entity

BACKGROUND: Cutaneous melanomas account for more than 95% of all cases of primary melanoma, making non-cutaneous primary melanomas truly rare. Cases of primary mucosal melanomas of the oral cavity have been widely described; however, instances of primary melanomas arising from salivary glands have been rarely described. To date, this is only the second case of primary melanoma of the submandibular gland. CASE PRESENTATION: This is a report of a case of a 36-year-old healthy male patient, who was referred to us with the chief complaint of a growing swelling on the left side of his lower jaw. Evaluations revealed an evident facial asymmetry in the frontal view with a firm, non-tender swelling. Initial orthopantomogram did not reveal any alterations in the trabeculation or morphology of the jaws and the surrounding structures. A soft tissue ultrasonography of the left submandibular gland and anterior region of mandible revealed a hypoechoic cystic mass with numerous micro-echoes. Further para-clinical examinations yielded the definitive diagnosis of primary melanoma of the submandibular gland. Moreover, no evidence of distant osteometastasis was observed in whole-body scans. Subsequent surgical management with the approach of excising the submandibular salivary gland and concurrent selective neck dissection was implemented. CONCLUSIONS: This report emphasizes the importance of thorough examination and prompt referral to designated specialists in cases with suspicious behaviors which are unresponsive to treatments. It can be further concluded that melanoma can mimic a range of benign pathologies; therefore, putting it in the list differential diagnosis of similar lesions seems plausible.