Balloon cell melanoma of the skin. Part II: An electron-microscopic study

Electron microscopy of an oligomelanotic balloon cell melanoma confirmed the considerable presence of lipid vacuoles in the cytoplasm of the tumours cells. There was also a marked finding of glycogen. The tumour consisted of little cohesive cells only with sporadic specialized intercellular junctions of the desmosome or hemidesmosome type. No tonofibrils could be seen. The cell cytoplasm contained a large amount of cell organelles, while stage II melanosomes were observed only exceptionally. Some of the melanosomes of stage III were difficult to distinguish from the regressively altered cell organelles, particularly from mitochondria and lysosomeś. The prevailing findings of stage II melanosomes rather indicated organelles sui generis than phagocyted organelles. There were infrequent neurosecretory granules in some places of the cytoplasm. Quite numerous Langerhans' cells with Bierbeck's granules were demonstrated among the tumour cells.