Magnetic resonance features of sinonasal melanotic mucosal melanoma

Abstract

A 67-year-old man presented to ear, nose and throat department complaining of nasal congestion and recurrent epistaxis for 5 months. Nasal endoscopy revealed a pigmented polyp obstructing the right nasal cavity. MRI with contrast agent showed a right nasal cavity polypoid mass with hyper signal intensity (SI) both in non-enhanced T1-w and diffusion imaging, marked hypo SI in T2-w sequences and avidly contrast enhancement characterised by rapid wash-in without significant wash-out on dynamic perfusion imaging. Histological specimen showed epithelioid and spindle cells with focal intense pigmentations and immunohistochemical features compatible with primary melanotic sinonasal mucosal melanoma (SNM). As melanotic SNM shows MRI pathognomonic high non-enhanced T1-w SI, this case underlines the crucial role of MRI not only in assessing the local tumour extension/recurrence but also in increasing the diagnostic confidence of detecting melanotic SNM. Thus, MRI should be always performed in case of clinical–endoscopic suspicion of SNM.

Preoperative Misdiagnosis of Malignant Mucosal Melanoma of the Nasal Septum by MRI

“…Malignant mucosa melanomas are very rare cancers that account for just 1% of all cases of melanomas. 2 The most common sites are the head and neck, and the incidence is slightly, but not significantly, higher in women than men. 5 They are usually found in people younger than the age of 65.…”

“…2 Since malignant mucosal melanomas are composed of cells with a high post-irradiation regenerative capacity, radiation is not an effective management tool for malignant mucosal melanoma. 2 Radiotherapy is suggested in cases of residual tumor cells in the surgical margins or local recurrence. Chemotherapy is applied for palliative treatment or in metastatic cases.…”

“…Chemotherapy is applied for palliative treatment or in metastatic cases. 2 Recently, immunotherapies, such as anti-PD1/PDL-1 agents, have been suggested; however, specific data are lacking. In spite of these new therapeutic trials, the prognosis of malignant mucosal melanoma in the sinonasal cavity remains very poor.…”

Primary Mucosal Melanoma Presenting with a Unilateral Nasal Obstruction of the Left Inferior Turbinate

“…Several studies proved the heterogeneous appearance of mucosal melanoma at MRI, most commonly showing a high-intensity signal on T1 and a low-intensity signal on T2 images. This unusual behavior may be due to the high melanin content in the tumor [ 9 , 17 , 18 ]. Surgical treatment is the primary therapeutic option.…”

“…Nevertheless, malignant melanomas are characterized by heterogeneous contrast enhancement in T1 and T2, making a clear-cut diagnosis more difficult. MRI is also the best tool to identify the anatomical involvement of other structures, such as the skull and brain [ 9 ]. Finally, positron emission tomography (PET) is a complementary exam for staging the tumor to assess distant metastases and guide the therapeutic approach [ 10 ].…”