Melanotic oncocytic metaplasia of the nasopharynx: a report of seven cases and review of the literature

Abstract

We describe seven cases of melanotic oncocytic metaplasia of the nasopharynx and review five other cases in the literature. It is usually a small, brown to black lesion that occurs around the Eustachian tube opening, where abundant seromucinous glands and lymphoid tissue are present. Multiple or bilateral lesions are sometimes seen. All 12 reported cases are of Asian origin. Melanotic oncocytic metaplasia occurs predominantly in men (male:female=11:1), with a mean age of 68 years. Simple excisional biopsy appears to be curative. Microscopically, melanotic oncocytic metaplasia is a combination of oncocytic metaplasia of the epithelium of the gland and melanin pigmentation in its cytoplasm. Fontana-Masson staining and immunohistochemical staining of S-100 protein revealed numerous melanocytes with conspicuous dendrites in the glands and stroma, which probably transfer melanin to adjacent glands. The exact pathogenesis of melanotic oncocytic metaplasia is unknown, but we postulate that the lesion could be related to the oncocytic metaplasia of the seromucinous glands around the Eustachian tube, which is followed by the local production and/or acquisition of the melanin pigment, under the influence of certain neuropeptides in the vicinity. The recognition of melanotic oncocytic metaplasia is of clinical importance, as it may be misdiagnosed as a malignancy to the unwary.

Malignant Melanoma Arising in Association with Sinonasal Melanosis: A Case Report and Review of the Literature

“…Cases of melanotic oncocytic metaplasia demonstrate dendritic melanocytes which are S-100 positive but HMB-45 negative. To date melanotic oncocytic metaplasia has not been associated with the development of malignant melanoma [1,2,10,11]. In this review, we report a case of melanosis of nasal seromucinous glands arising within a Caucasian male and associated with a malignant melanoma primary within the nasal cavity.…”

Melanotic oncocytic metaplasia of the nasopharynx

“…Accordingly, smoking is hypothesized as a predisposing factor for MOMN [1]. However, a positive smoking history was only attainable in six cases [1,10,11], including the present case. Ethnic background of East Asian may be another predisposing factor.…”

“…Furthermore, smoking is considered to be related to oral melanin pigmentation [15]. Accordingly, smoking is hypothesized as a predisposing factor for MOMN [1]. However, a positive smoking history was only attainable in six cases [1,10,11], including the present case.…”

“…Melanotic oncocytic metaplasia of the nasopharynx (MOMN) is a rare benign lesion, occurring predominantly in Asian men [1]. It is usually diagnosed as melanoma or another malignant tumor in clinical impression.…”

A Dark Pigmented Spot in the Nasopharynx

“…While a few cases located at the pharynx have been reported, the lesion tends to occur predominantly in the nasopharynx among Asian men. 1,2 To date, only about 20 cases have been reported in English literature. Commonly, the lesion is an incidental finding because there are no symptoms in most cases.…”