Electron microscopy findings in malignant melanoma of nose.

Electron microscopic examination of malignant melanoma tumour tissue taken from a patient who has survived with the tumour without metastases for 13 years has shown spherical melanosomes with no internal fibrillar structure. This finding and other cell features described, suggest that this melanoma developed from Dubreuilh's melanosis rather than melanocytic change in a junctional naevus.