Light and electron microscopic features of a case of ceruminous adenocarcinoma are presented and compared to normal ceruminous glands. A survey of the literature disclosed 4 types of ceruminoma: adenoma, adenocarcinoma, adenoid‐cystic carcinoma, and mixed tumor. The pathogenesis and histologic features of each type are discussed. Because biologic activity varies with the histologic pattern, and because of the greater frequency of malignancy as compared to other cutaneous apocrine tumors, it is recommended that the generic term “ceruminoma” be retained for apocrine tumors arising in the external auditory canal.

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Three cases of Dial and Liebow's intravascular bronchioloalveolar tumour are described, with emphasis on ultrastructure and histogenesis. The tumour cells are quite different from adjacent reactive alveolar cells and electron microscopy does not support the suggested alveolar cell origin. The tumour cells contain abundant microfilaments, moderate amounts of rough endoplasmic reticulum and varying numbers of Weibel-Palade bodies. With features of smooth muscle, myofibroblast and endothelial cell differentiation, a vascular origin from precursor mesenchymal cells such as the vasoformative reserve cells is suggested.

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