Metastases of Melanoma to Head and Neck Mucosa: A Report of Short Series

Definitive treatment for head and neck mucosal melanoma

Head and neck mucosal melanoma is a rare clinical subtype of melanoma or head and neck cancer. Mucosal melanoma is aetiologically and molecularly distinct from cutaneous melanoma. The therapeutic efficacy of immune checkpoint inhibitors for head and neck mucosal melanoma remains unclear. Surgery is considered as the mainstay of treatment for locally advanced head and neck mucosal melanoma, and adjuvant radiotherapy has a role in local disease control. New treatment modalities, such as targeted therapy and immunotherapy, have changed the treatment of cutaneous melanoma. However, patients with mucosal melanoma have been excluded from most Phase III clinical trials. Due to its rarity, outcome data for locally advanced head and neck mucosal melanoma are scarce and are mainly based on retrospective studies with limited case numbers. The objective of this review was to provide an update and overview of clinical trials, prospective observational studies and retrospective studies and discuss future directions for multimodal treatment of locally advanced head and neck mucosal melanoma.

Cutaneous Malignant Melanoma Metastatic to the Larynx and Trachea: A Case Report and Review of the Literature

Malignant melanoma rarely develops in mucous membranes. Statistical data show that approximately 0.6-9.3% of patients with cutaneous malignant melanoma will develop metastases in the upper aerodigestive tract mucosa, and within these metastatic sites, the least common are the laryngeal and tracheobronchial ones. This exceedingly rare clinical entity has no clear treatment recommendations; radical surgery does not seem to benefit the patient in term of life expectancy. We present the case of a 56-year-old male patient diagnosed with laryngeal and tracheobronchial melanoma metastases. Prior to admission to our clinic the patient had a personal history of malignant melanoma of the nuchal region operated on 7 years ago, malignant melanoma of the gallbladder and metastatic left axillary polyadenopathy for which he underwent surgical treatment 3 months prior. Histopathological and immunohistochemical reports established the diagnosis of laryngeal metastasis of malignant melanoma. Genetic molecular analysis was positive for B-Raf (BRAF) gene and hence Vemurafenib was administered, with a favorable outcome at the one-year follow-up. Nevertheless, there are currently no clear universally accepted guidelines for the treatment of laryngeal melanoma, mainly due to the rarity of this clinical entity. We conducted a review of similar cases reported in the literature. Interestingly, reviewing the cases reported in the literature, it appears that laryngeal metastases of a primary cutaneous melanoma are more common in men, with an average time to metastasis of 4.3 years.

Mucosal Melanoma: Pathological Evolution, Pathway Dependency and Targeted Therapy

Mucosal melanoma (MM) is a rare melanoma subtype that originates from melanocytes within sun-protected mucous membranes. Compared with cutaneous melanoma (CM), MM has worse prognosis and lacks effective treatment options. Moreover, the endogenous or exogenous risk factors that influence mucosal melanocyte transformation, as well as the identity of MM precursor lesions, are ambiguous. Consequently, there remains a lack of molecular markers that can be used for early diagnosis, and therefore better management, of MM. In this review, we first summarize the main functions of mucosal melanocytes. Then, using oral mucosal melanoma (OMM) as a model, we discuss the distinct pathologic stages from benign mucosal melanocytes to metastatic MM, mapping the possible evolutionary trajectories that correspond to MM initiation and progression. We highlight key areas of ambiguity during the genetic evolution of MM from its benign lesions, and the resolution of which could aid in the discovery of new biomarkers for MM detection and diagnosis. We outline the key pathways that are altered in MM, including the MAPK pathway, the PI3K/AKT pathway, cell cycle regulation, telomere maintenance, and the RNA maturation process, and discuss targeted therapy strategies for MM currently in use or under investigation.

A Review of the Aetiopathogenesis and Clinical and Histopathological Features of Oral Mucosal Melanoma

Oral mucosal melanoma is an uncommon, usually heavily melanin-pigmented, but occasionally amelanotic aggressive tumour with a poor prognosis. Despite radical surgery, radiotherapy, or chemotherapy, local recurrence and distant metastasis are frequent. Microscopical examination is essential for diagnosis, and routine histological staining must be supplemented by immunohistochemical studies. The aetiology is unknown, the pathogenesis is poorly understood, and the 5-year survival rate rarely exceeds 30%. In most cases, oral mucosal melanoma arises from epithelial melanocytes in the basal layer of the epithelium and less frequently from immature melanocytes arrested in the lamina propria. In both cases the melanocytes undergo malignant transformation, invade deeper tissues, and metastasize to regional lymph nodes and to distant sites. Very rarely metastasis from skin melanoma may give rise to oral mucosal melanoma that may be mistaken for primary oral mucosal melanoma. The pathogenesis of oral mucosal melanoma is complex involving multiple interactions between cytogenetic factors including dysregulation of the cKit signalling pathways, cell cycle, apoptosis, and cell-to-cell interactions on the one hand and melanin itself, melanin intermediates, and local microenvironmental agents regulating melanogenesis on the other hand. The detailed mechanisms that initiate the malignant transformation of oral melanocytes and thereafter sustain and promote the process of melanomagenesis are unknown.