Bronchial granular cell tumor. Presentation of three cases with tissue culture and ultrastructural study

Three granular cell tumors, two arising from the bronchi and one from the trachea, are described. Two of the cases were studied by tissue culture and electron microscopy of the original tumor tissue and the cultivated cells. The granular cells grew actively in culture and showed a specific pattern in vitro different from tumors of fibrohistiocytic and schwannian origin. Ultrastructural examination of the newly grown cells allowed follow-up of the progressive cytoplasmic granulation of cells, with a transition from elements with an ultrastructural morphology consistent with the "early granular cells" described in tumor tissue in previous studies to fully developed mature granular cells.