HISTOPATHOLOGICAL STUDIES ON THE TUMOURLET OF THE LUNG WITH SPECIAL REFERENCE TO THE CYTOGENESIS OF PROLIFERATING CELLS

Eight foci of tumourlets of the lung and one allied lesion obtained from autopsy cases were histologically examined. The tumourlet of the lung consisted of epithelial cells and was considered to be a benign lesion. Small sized-lesion, uniformity of proliferating cells with very few mitosis and existence of associated lung lesions were documented as characteristic findings. However, the histopathogenesis of the tumourlet was not fully clarified. It was found that proliferating cells of tumourlets often show argyrophilia and contain numerous neurosecretory-like granules in their cytoplasm. These characteristics are very similar to Kultschitzky-like cells of the lung.