Squamous cell carcinoma of bronchus: polypoid granules and mitochondrial densities found by electron microscopy.

In the course of studying a series of human bronchial and lung carcinomas by electron microscopy, we have come across a squamous cell (epidermoid) carcinoma containing two different kinds of small bodies that have not been described previously. One of them took the form of small round dense granules projecting from the surface of keratinizing tumour cells, which we have termed 'polypoid granules'. The other consisted of small oval dark densities associated with the outer membranes of the mitochondria of non-keratinizing tumour cells, which we have termed 'mitochondrial densities'. The composition of the bodies could not be identified by histochemical methods, but they are of interest since they have not been recorded previously, and may be concerned in some way with ectopic hormone production by the tumour.