Most tumors are located on the lateral wall of the nose, while in the paranasal sinuses it is most often localized in the maxillary sinus.

They are mainly manifested by non-specific symptoms, which include nasal obstruction, epistaxis, facial pain, and rhinorrhea, while in the advanced stage symptoms such as diplopia and proptosis may occur. [2,4-7,10] Therefore, there is usually a long interval between the appearance of symptoms and the diagnosis of the disease, primarily with localization in the paranasal sinuses.

SNMM are known to have a specific pattern of chromosomal changes. Recent data on immunohistochemical and genetic profiling indicate potentially significant changes in the KIT gene and a minor role for BRAF gene mutations in the pathogenesis of mucosal melanomas. [1,2,9] According to various studies, the somatic mutations that characterize SNMM are KIT, 0–40 %, NRAS 10–50 %, and BRAF 0–10 %. [9] The tyrosine kinase inhibitor (Imatinib) is effective in patients with c-KIT mutations. [2,9]

Classical immunohistochemical criteria for mucosal melanoma are negative epithelial, endocrine, lymphoid, and muscle markers associated with one or more positive melanocyte markers: protein S100, HMB-45, and Melan-A. [3-6,10,11] Current guidelines state that ≥ 2 positive markers are required for the diagnosis of mucosal melanoma. [3] In addition, SNMMs are more likely to show vascular invasion, probably due to numerous arterial anastomoses in the nasal passages. [4]

The differential diagnosis of SNMM includes olfactory neuroblastoma, lymphoma, plasmacytoma, undifferentiated carcinoma, adenocarcinoma, rhabdomyosarcoma, malignant fibrous histiocyte, leiomyosarcoma, angiosarcoma, malignant fibrous histiocyte, and neurogenic sarcoma. [6,11]

SNMM treatment includes surgery, radiotherapy, chemotherapy, and immunotherapy, either alone or in combination.

Extensive surgical excision with clear resection lines is the main therapeutic option, as it provides the best chance of long-term survival in these patients. [1,2,5,8,9] The surgical approach and extent of resection depend on the location and size of the tumor. Some authors suggest that endoscopic resection may be associated with better clinical outcomes. [1,12] Proponents of this approach argue that it has lower complication rates, although the tumor is resected in parts rather than en bloc. The advantage of endoscopic surgery lies in the potential reduction of morbidity. In a review of 58 patients treated for SNMM at the MD Anderson Cancer Center, the endoscopic approach resulted in a better two-year overall survival than the open approach. [1] However, these results should be considered because the endoscopic approach is most commonly used for smaller tumor lesions.

The role of neck dissection in SNMM which is an intern as a NO is clearly defined. Numerous authors do not recommend prophylactic neck dissection in SNMM, given the low rate of regional metastases. [1,2,4,5,9] The sentinel lymph node biopsy technique used in cutaneous melanoma is currently being investigated in mucosal melanoma. The reported rates of regional lymph node metastases in SNMM are 8-11 %, and hematogenous metastases are detected in 6 % of patients (lungs, brain, bones, liver). [2] Our patient had multiple metastases in the lymph nodes of the neck at the time of presentation, but she had no distant metastases.

Adjuvant postoperative radiotherapy provides significant benefits for loco-regional disease control but does not affect overall survival. Radiotherapy as the only modality has not shown a significant advantage for local control or survival, and as such, in most cases, it is applied mainly to large tumors that are not operable. [1] Successful control of the hematogenous spread of the disease requires aggressive systemic therapy. However, the effects of systemic therapy have so far been unsatisfactory, as it has largely failed to provide significant survival benefits. [1] The clinical benefit of immunotherapy with ipilimumab, a monoclonal antibody associated with cytotoxic T lymphocytes, in the treatment of unresectable melanoma has recently been demonstrated in a large, randomized study. The authors observed a significant improvement in overall survival in patients receiving ipilimumab. [1,2,9] In one study of patients with metastatic melanoma resistant to ipilimumab, nivolumab showed a higher overall survival rate (72.9 %) than dacarbazine (42 (1 %). [9] The use of other agents, such as pembrolizumab, also showed a higher survival rate without progression and toxicity. [7] Immunotherapy with interleukin 2 or interferon-alpha (IFNα) is currently under evaluation, either alone or in combination with chemotherapy. [2]

Bartell et al. have used a chemotherapy regimen that includes vincristine, cisplatin, and dacarbazine with biological agents (such as IFN-α and IL-2) in patients with mucosal melanoma and metastatic disease. A good clinical response was observed in 47 % of patients, with 27 % of patients showing a complete response. The authors suggested that chemotherapy should be considered in patients with metastatic disease or inoperable tumors. [4]

The most common cause of death in SNMM is distant metastases. Reported five-year overall survival ranges from 20-60 %, with an average of 27 %. [1,5,6,9] Poor survival in patients with SNMM is mainly attributed to aggressive local and hematogenous spread of the disease.

Certain histopathological features of SNMM are predictors of poor survival and they include vascular invasion, necrosis, and polymorphic populations of tumor cells. [6] Tumor localization has also been shown to influence prognosis. Patients with nasal tumors have a better prognosis than those with localization in the paranasal sinuses. [9] Failure in local disease control is associated with an increased risk of distant metastases and a significant reduction in overall survival. However, more than 50 % of patients will develop distant metastases despite good local tumor control. [2] Thus, Nandapalan et al. reported a local recurrence rate of 52 %. [4] Finally, Kalogirou EM et al. reported a case of SNMM recurrence 10 years after treatment, suggesting that this tumor carries a long-term risk of recurrence. [10]