Dear Editor,
 
Mucosal melanoma of the head and neck (MMHN) region accounts for ~1.3% of all melanomas affecting the body (1). The conjunctiva is most frequently involved, followed by the upper aerodigestive tract. The oral and nasal cavities share almost 48% and 44% of the melanomas occurring in the upper aerodigestive tract. Paranasal sinuses harbor the bulk of the remainder of cases. Rarely are the pharynx and larynx involved (2). Nearly 80-90% of oral mucosal melanomas (OMM) arise from the keratinizing mucosa of the hard palate and maxillary gingiva.  Buccal mucosa, mandibular gingiva, and the floor of the mouth are rather unusual sites (3). The amelanotic version of melanoma constitutes ~13% of all MMHN, which is more than its cutaneous incidence of 1.8-8.1% (4).
Case 1
The 42-year-old lady presented with an irregular blackish mucosal patch involving the inner surface of the upper lip (Figure 1A). Any pain or tenderness was absent. Only mere discomfort to the part led to its self-localization. Palpably, the mucosa appeared slightly thickened. Clinically, hemangioma and malignant melanoma surfaced as possible differentials. On histopathology: The thinned-out mucosa overlying diffuse sweeps of heavily pigmented tumor cells (Fig. 1B). These epithelioid tumor cells contained abundant cytoplasm, flocked with dense pigment granules that eventually obliterated their cellular details. Nuclei appeared vesicular with prominent nucleoli. Histomorphologically, the diagnosis of malignant melanoma was evident. Simultaneous positron emission tomography (PET) negated any further dissemination of the melanoma. Postoperatively, after a regimen of radiotherapy and chemotherapy the patient was followed up at 6 months interval without any relapse or recurrence.
Case 2
A 56-year-old man attended the otorhinolaryngology outpatient clinic with a rapidly enlarging left paranasal mass on his face. Computed tomography (CT) delineated a homogeneous solid tumor arising from the maxillary sinus, encroaching and compressing onto the nasal cavity (Fig. 1C). With a primary suspicion of sinonasal carcinoma or lymphoma, a punch biopsy was taken from the mass. Histologically, undifferentiated tumor cells appeared in diffuse sweeps undermining the ulcerated mucosa (Figure 1C, 1D). The polygonal tumor cells bore grossly irregular large nuclei, marked nuclear pleomorphism, frequent intranuclear cytoplasmic pseudoinclusions, vesicular chromatin, prominent nucleoli, and abundant pale eosinophilic cytoplasm (Fig. 1E). From such a dubious histomorphology sinonasal undifferentiated carcinoma, poorly differentiated squamous cell carcinoma (SCC), large B-cell lymphoma and amelanotic form of malignant melanoma posed as closest differentials. To their discrimination, a battery of immunohistochemical (IHC) markers were exercised. Cytokeratin (CK) 5/6, CD 45, and S100 were applied in the primary panel. The tumor cells expressed strong nucleocytoplasmic reactivity with S100, indicative of malignant melanoma (Figure 1F). While the other two reagents stained negatively (Figure 1I, 1J). HMB 45 was applied for confirmation. Tumor cells expressed strong cytoplasmic granular positivity, affirming it as amelanotic melanoma (Figure 1J). PET scan detected widespread dissemination to cervical lymph nodes, brain and lungs. The patient was immediately subjected to combination therapy. Despite this, he died of the disease after 4 months.