Macroscopic and microscopic findings of the lesion. A: Endonasal view of the nasopharynx, with multiple melanotic lesions around the Eustachian tuber (left side). B: Microscopic findings of the lesion (hematoxylin and eosin stain, low magnification). C: Microscopic findings of the lesion (hematoxylin and eosin stain, high magnification). Plump epithelial cells with eosinophilic cytoplasm and many brown pigmented granules are arranged in a tubular pattern. D: Immunohistochemical findings of the lesion (S-100). S100-positive HMB45-negative dendritic cells were scattered in the lesion (arrows). By counterstaining with Giemsa stain, melanin pigment showed heterochromasia (green).
Kondo et al. Diagnostic Pathology 2010 5:5 doi:10.1186/1746-1596-5-5