1. Introduction
Sino-nasal melanoma is a malignant neoplasm of the melanocyte. Melanocytes are derived from the neural crest; melanomas usually occur on the skin. They can arise in other locations where neural crest cells migrate, such as the gastrointestinal tract and brain [1] .
The five-year relative survival rate for patients with stage 1 melanoma of the head and neck is more than 90%, compared with less than 20% for those with metastatic disease [2] .
The discrepancy in mortality rate is high when compared between primary melanoma (approximately 11%) and metastatic melanoma [3] . Metastatic melanoma patients typically have a low survival rate due to the delay in seeking medical aid including poor efficacies of current cancer therapies. The best treatment options are surgical intervention along with radiation and/or chemotherapy to control the disease [4] .
Patients with sino-nasal malignant melanoma present with complaints of epistaxis, nasal block, and persistent rhinorrhoea. Histologically, melanoma’s appearance can vary. The cells may appear as stratified squamous epithelium and stroma can be infiltrated by malignant cells. These malignant cells are round to ovoid, exhibit moderate pleomorphic hyperchromatic nuclei and some have prominent nucleoli [2] . Immunoperoxidase studies are very useful, including the use of HMB-45, S100, and Melan A [2] .
According to studies, sino-nasal malignant melanoma is highly treatable when discovered in the early stages. However, in the cases of advanced stages as disease metastasizes, the treatment options become limited, and the survival rate decreases to months. The site of the tumor origin is occasionally difficult to identify due to the extensive local destruction it causes and the large size of the tumor. There is a delay in diagnosis due to its nonspecific clinical features.
2. Case Presentation
A 46-year-old Asian lady presented with epistaxis for one year of duration and dysphagia for 6 months. She also experienced the loss of appetite and significant weight loss and was unable to lie flat for the last 3 months. She sought medical attention due to sudden shortness of breath.
At rest, the patient presented with audible stridor and hypernasal speech. Upon neck examination, single left cervical lymph node palpable at level II measuring about 4 × 5 cm, firm, fixed and non-tender. Tuning fork test revealed a negative Rinne’s test for both right & left ears, the Weber test was not lateralized. The findings were confirmed with Tympanometry showing a type B for both ears. Pure tone audiometry showed mild to moderate hearing loss over left ear and mild to severe hearing loss over right ear indicating bilateral conductive hearing loss due to mass effect on bilateral eustachian tube. In the oral cavity, the nasal mass was seen to extend inferiorly until the level of oropharynx.
Nasoendoscopy showed a mass occupying both right and left nasal cavities obliterating the post nasal space with thick mucus secretion.
In view of impending air-way compromise, patient underwent tracheostomy under local anaesthesia.
CT of head and neck showed large enhancing mass measuring approximately 5.8 × 7. 6cm (AP × W) completely obliterating the nasopharynx, oropharynx, and part of hypopharynx with local infiltration and cervical lymphadenopathies (Figure 1 and Figure 2). The mass is seen extending superiorly to involve both posterior nasal spaces bilaterally and causing effacement of both parapharyngeal spaces (Figure 3). There is a heterogenous lesion in the left infratemporal fossa with association of erosion of the adjacent wall of left maxillary sinus. The right infratemporal space is preserved.
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Figure 1. Axial plane. Computed tomography of the head. A large mass blocking the air flow at the bilateral nasal cavity is clearly visible.
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Figure 2. Sagittal plane. Computed tomography of the head. A large mass obliterating nasopharynx, oropharynx, and part of hypopharynx.
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Figure 3. Coronal plane. Large mass causing effacement of both parapharyngeal spaces
CT of thorax and abdomen revealed left lung lesion, multiple hypodense liver lesions, bilateral breast lesions, enlarged mesenteric and pelvic lymphadenopathies, subcutaneous lesions in the left shoulder, bulky left adrenal gland, ill-defined hypodense pancreatic tail lesion, which extends into the splenic vein which may represent metastasis.
FNAC of enlarged cervical lymph node showed hypercellular composed of sheets of malignant looking cells arranged singly and few in clusters (Figure 4 and Figure 5). The cells are highly pleomorphic with high NC ration, irregular coarse chromatin nuclei having prominent nucleoli and multinucleoli. Some of the cells exhibit atypia with very large distorted hyperchromatic nuclei and tumor giant cells. Mitoses and cannibalism are evident. Scattered neutrophils are present in background.
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Figure 4. Left nasopharyngeal mass 200× (magnification) haematoxylin and eosin.
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Figure 5. Right nasopharyngeal mass 100× (magnification) haematoxylin and eosin.
In view of the clinical findings, the working diagnosis was towards nasopharyngeal carcinoma as NPC is endemic in our place of practice. Biopsy was taken and histopathological examination revealed malignant melanoma with extensive tumor necrosis. The malignant cells were positive for Melan A (Figure 6) and S100 (Figure 7). The cells were negative for CKAE1/AE3, Synaptophysin, Chromogranin A, NSE, INSM-1 and LCA. CD5 6 is inconclusive, Ki-67 is high (80% - 90%).
The patient was staged as advanced stage of sino-nasal malignant melanoma. However, even before breaking the bad news, patient defaulted follow up and eventually passed away before initiation of therapy.
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Figure 6. Immunoperoxidase staining positive for Melan A in 40× (magnification).
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Figure 7. Detected S100 protein in immunoperoxidase studies seen in 100× (magnification).
3. Discussion
Sino-nasal malignant melanoma is uncommon as mucosal melanoma of the head and neck depict approximately less than 1% of all reported melanomas [5] . It is an aggressive, and fast progressing tumour which results in 4% of sino-nasal malignancies [6] . Malignant melanoma in the sino-nasal region is exceptionally rare with mean 5-year survival is 0% - 30% [6] . This tumour arises from melanocytes derived from neural crest tissue, which are the progenitors of the lesion and etiopathogenesis remains unclear. The prevalence of this condition is of mean age ≥ 60 years and more commonly found in males [6] . The disease is found more in white populations compared to blacks, and in individuals with higher exposure to sunlight [7] .
Sino-nasal malignant melanoma is commonly arise from nasal cavity, inferior, middle nasal conchae, septum, lateral wall of nasal cavity and facial sinuses [6] which is dissimilar to nasopharyngeal carcinoma, which originates from the fossa of Rosenmuller (Table 1).
The most common symptoms reported are unilateral nasal obstruction, nasal congestion, and bleeding with variable duration between 3 - 24 months. In our case, patient presented with the symptom of epistaxis and dysphagia which is similar to the symptoms mentioned above, which has been diagnosed clinically as nasopharyngeal carcinoma as differential diagnosis. Nasoendoscopy usually reveals the large mass obliterating nasal cavity. Some cases described the mass as reddish pink with black pigmentation at base, and firm in consistency with irregular surface [8] .
Computed Tomography (CT) scan of the head showed that large enhancing
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Table 1. Comparison between sinonasal carcinomas.
Abbreviations: M: Male; F: Female.
mass, and in our case, the mass has completely obliterating the nasopharynx, oropharynx, and part of hypopharynx with local infiltration and cervical lymphadenopathies. This report displayed the classic symptoms and diagnostic findings of nasopharyngeal carcinoma.
To establish the diagnosis, biopsy of the lesion for histochemistry and immunohistochemistry is the gold standard, although this procedure maybe associated with high risk of dissemination of the tumor cells into circulation [5] . The cytological findings are found to show positive staining with anti-S-100, HMB-45, and anti-vimentin especially in metastatic malignant melanomas. Not all mucosal melanomas have positive staining with anti-S-100 [6] and therefore, another set of markers must be investigated to establish diagnosis.
In our case, diagnosis was established as the malignant cells were positive for Melan A and S100. Another subtypes of malignant melanoma, also known as amelanotic melanoma has high affinity for perineural spread and low rate of lymphatic metastasis [1] which may be misdiagnosed. In such cases, immunohistochemistry is useful in reaching the diagnosis.
For this aggressive disease, treatment can be curative with surgical removal which includes traditional open or endoscopic surgery [9] and followed by radiotherapy or palliation with chemotherapy or radiotherapy. Radiotherapy aids in local control and is indicated in the presence of positive surgical margins, local recurrence, locally advanced tumour, or sometimes for palliative purposes. However, it has also been reported to not improve overall survival [6] .
Despite many different regimes, most have shown unsatisfactory results with median Overall Survival (OS) and Disease-Specific Survival (DSS) being 32 and 50 months as reported [9] . Sino-nasal malignant melanoma is known to have a high recurrence and metastasis rate, and therefore patients should maintain lifelong follow-up with PET/CT which is a valuable tool for assessment. The factors for poor prognosis of this condition include advanced age, size of the tumor, location of the tumor (especially paranasal sinuses and nasopharynx), cellular pleomorphism and distant metastasis. It has no significant associations observed for gender, margin status, or complete resection [9] .
4. Conclusion
Sino-nasal malignant melanoma with its rare occurrence, it is important to exclude other differential diagnoses with histopathology and immunohistochemistry examination. The significance of establishing the diagnosis enables us to guide patients thoroughly for treatment. It is vital to get patients with the correct management and to the aggressive nature of this disease.