Melanotic Oncocytic Metaplasia of the Nasopharynx: A Report of Three Cases and Review of the Literature

Abstract

Melanotic oncocytic metaplasia of the nasopharynx is a rare condition which is characterized by the presence of usually a small, brown to black colored pigmented lesion around the Eustachian tube opening. Although it is a benign lesion, it may be clinically misdiagnosed as malignant melanoma. Microscopically, melanotic oncocytic metaplasia is a combination of oncocytic metaplasia of the epithelium of the gland and melanin pigmentation in its cytoplasm. In our present study, we report three cases of melanotic oncocytic metaplasia of the nasopharynx. All the three cases occurred in men and were presented as multiple black pigmented lesions around the torus tubarius. Microscopically, mucous glands with diffuse oncocytic metaplasia and numerous black pigments were observed. No cellular atypia was observed. Immunohistochemically, the scattering of S-100 protein-positive, and human melanoma black 45-negative dendritic melanocytes was evident. This is the first report of cases of melanotic oncocytic metaplasia of the nasopharynx in Korea.

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

“…The luminal lining cells contained not only melanin pigment (positive Fontana-Masson reaction) but also were immunoreactive for HMB-45, S-100 protein and melan A suggesting the production of melanin in these cells. Earlier reports of melanotic oncocytic metaplasia demonstrated melanin pigment in the seromucinous glands but the cells were HMB-45 negative [1]. This finding suggested that the melanin pigment may only have been phagocytized by the oncocytic epithelium rather than produced in these cells.…”

“…While two prior reports and our case had melan pigment within glandular epithelum, our case was positive for HMB-45 and melan A while the others were not. Additionally, the prior reports of melanotic oncocytic metaplasia occurred in Asian men [1,2] our patient was a Caucasian man. Finally, the seromucinous glands in our case did not show oncocytic change.…”

“…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.…”

“…Pigmentary disorders of the nasal mucosa and submucosal glands are rare and include melanocytic oncocytic metaplasia [1,2], melanocytic hyperplasia of the nasal respiratory epithelium, and primary malignant melanoma [3]. Intranasal malignant melanoma represents approximately 1% of total malignant melanomas arising at all body sites [4].…”

“…Melanotic oncocytic metaplasia shows coexistence of oncocytic metaplasia and melanin pigmentation within the same gland [1,7,8]. The precise origin of the melanin pigment within the oncocytic epithelium is unclear.…”