SUMMARY:We observed 2 cases of malignant melanoma arising from the eustachian tube with MR imaging. In this region, we explored further characteristics of primary mucosal melanoma. We discuss the value of using MR imaging to diagnose and treat patients with melanoma in the eustachian tube. In addition, we introduce the key points to differentiate melanoma from some common diseases in the region.
Malignant melanoma primarily affects the skin, rarely the mucosa. Melanoma of the upper airway mucosa constitutes approximately 1% of the total melanoma of the head and neck.1 Primary melanoma of the eustachian tube is even rarer. In a series of 158 cases of mucosal melanoma of the upper airway, only 2 cases were located at the eustachian tube orifice in the nasopharynx.2 To the best of our knowledge, only 6 cases of primary melanoma of the eustachian tube have been reported in the literature to date [2][3][4][5] ; unfortunately, the corresponding MR imaging findings were not described effectively. During the past 5 years, melanoma of the eustachian tube in the nasopharynx has been positively proved through histopathology in 2 patients at our hospital. These 2 patients underwent MR imaging.
Case Reports
Case 1A 75-year-old man with mild hypertension and an intermittent epistaxis for the past 20 days was examined. An otorhinolaryngologic examination showed serous otitis media of the left ear and a brownblack soft-tissue mass with surface irregularity in the left nasopharynx. The pharyngeal orifice of the left eustachian tube was obstructed. MR imaging revealed an elliptic well-defined 1.2 ϫ 2.0 ϫ 1.4 cm mass in the left nasopharynx, arising from the left eustachian tube. The lesion showed signal intensity hyperintense to gray matter on T1-weighted images and hypointense signal intensity on T2-weighted images with moderate homogeneous contrast enhancement following the administration of contrast material (Fig 1A-C). The timeintensity curve of dynamic contrast-enhanced (DCE) MR imaging was a rapidly enhancing and rapid washout type (Fig 1D, -E). The lesion was complicated with serous otitis media of the left ear, which showed hypointense signal intensity on T1-weighted images and hyperintense signal intensity on T2-weighted images without significant contrast enhancement. Neither an enlarged retropharyngeal node, evidence of head and neck melanoma, nor systemic abnormalities were observed. A surgical specimen of the brown-black mass in the left eustachian tube was histopathologically proved to be malignant melanoma. On immunohistochemistry, tumor cells were strongly positive for S-100, vimentin, and melanoma antibody HMB45.
Case 2A 35-year-old woman with no significant medical history presented with a 2-year history of hearing decrease and with a 1-month intermittent epistaxis. An otorhinolaryngologic examination revealed serous otitis media of the left ear and an irregular coarse friable grayblack soft-tissue mass occupying the whole pharyngeal orifice of the left eustachian tube in the nasopharynx. MR imaging showed an el...