Published in Cancer Detection and Prevention 2000; 24(Supplement 1).

Melanin pigmented oncocytic metaplasia of the nasopharynx

E Hirakawa MD 1, H Miki MD 2, M Ohmori MD 2, S Kobayashi MD 2, K Yamamoto BS 1

1 Dept Medical Technology, Kagawa Prefectural College of Health Sciences,, 2 Dept Pathology, Kagawa Medical University, Kita-gun, Japan,

AIMS: Oncocytic metaplasia and hyperplasia of the seromucinous glands is a rare tumor-like lesion in the upper respiratory tract. It is extremely rare for them to show melanin pigmentation and three cases have been reported in the literature. We report a case of melanin pigmented oncocytic metaplasia of the nasopharynx. METHODS: A 64-year-old man presented with a history of discomfort of the throat of a few weeks' duration. Nasoscopic examination revealed multiple small, brown pigmentations at the left supurapharynx, the base of the left nasal cavity and pharyngeal openings of the auditory tube on both sides. The lesions were biopsied for histological examination. RESULTS: Microscopically, the lesion showed a glandular pattern of oncocytic epithelium with abundant pigmented granules and melanophages in the surrounding stroma. Immunohistochemically, the dendritic cells in the basal layer were positive for S-100 protein. Electron microscopic study revealed numerous fully melanized melanosomes and hypertrophied mitochondria in the oncocytic cells. CONCLUSIONS: Oncocytic cells do not produce melanin for themselves, melanin granules apparently being transferred from the adjacent dendritic cells to the oncocytic cells. This transfer of melanin seems to occur after the onset of oncocytic metaplasia; little melanin pigment was present in the normal respiratory epithelium. It is possible that oncocytic cells produce a migration factor and trophic substances that stimulate melanin production of the melanocytes.

KEY WORDS: Melanocyte, Oncocytic metaplasia, Electron microscopy, Respiratory epithelium, Non-neoplastic tumor-like condition.

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Paper presented at the International Symposium on Impact of Biotechnology on Cancer Diagnostic & Prognostic Indicators; Geneva, Switzerland; October 28 - 31, 2000; in the section on prognostic markers.