Large intracytoplasmic body in lung cancer compared with Clara cell granule.

Large intracytoplasmic bodies in tumor cells of different pulmonary neoplasms were morphologically studied. In 27 of 105 cases of surgically resected lung tumors, large intracytoplasmic bodies were found in 13 adenocarcinomas, 9 squamous cell carcinomas, and 5 large cell carcinomas. These bodies appeared most frequently in large cell carcinomas and in well-differentiated adenocarcinomas, particularly of the Clara cell type. In squamous cell carcinomas, they were seen only in nonkeratinizing polygonal tumor cells. Large intracytoplasmic bodies in different pulmonary tumors and Clara cell granules in Clara cell carcinoma showed similar histochemical staining reactions. Electron microscopically, both large intracytoplasmic bodies and Clara cell granules appeared membrane bound and contained electron-dense matrices. The results suggest that large intracytoplasmic bodies in lung carcinoma cells may be a variant of Clara cell granules, only differing in size.