Mucosal melanoma — clinical presentation and treatment based on a case series

Abstract

Melanoma is malignant disease originating from melanocytes (pigment cells that occur mainly in the skin and constitute a type of defence from ultraviolet radiation). Melanocytes also occur outside of the skin (among others — in the eyeball, the mucosal lining of the digestive tract from the oral cavity to the anus, the nasal cavity and the paranasal sinuses, and the urinary and reproductive tracts). Many known cases of melanoma in the aforementioned locations exist. The main factor responsible for the development of skin melanoma is ultraviolet radiation. In the case of mucosal melanoma, aetiological factors are still unknown. Mucosal melanoma most often develops in places that are hidden and not accessible through standard testing. Therefore, the disease develops without any signs for a long period of time before the proper diagnosis is established (usually at a disseminated stage, at a point where no successful localised treatment can be applied), which, in combination with a more aggressive course in comparison to more typical locations (the skin, the eyeball), a different sensitivity to systemic treatment (usually the lack of a mutation in the BRAF gene), and the lack of a separate standardised treatment procedure, is the cause of worse outcomes and poor prognosis. Mucosal melanomas occur very rarely (about 1.5 % of all melanomas); however, the knowledge that a melanoma may also develop in locations that are often omitted during routine examination (the anus, the oral cavity, the urogenital region), may increase the chances of early diagnosis and attaining better treatment results. In this paper, a brief description of the characteristics of mucosal melanoma is presented, along with a presentation of the most common locations, symptoms, diagnostic possibilities, and available treatment (including immunotherapy). Based on the available literature and personal experience, several cases of patients treated in the Institute of Oncology are described.