Electron microscopy of small cell carcinoma of the lung with special reference to the crush phenomenon

Four cases of small cell carcinoma of the lung were studied ultrastructurally. The tumor cells contained scattered neurosecretory granules. Areas of the tumor that showed the characteristic crush phenomenon were found to be surrounded by myofibroblasts. It is proposed that the crush phenomenon is caused by contraction of the encircling myofibroblasts. The myofibroblasts and collagen may also cause degeneration and necrosis of the tumor cells. Myofibroblasts have not been observed in other histologic types of carcinoma of the lung.