Diagnosis of lung cancer by fibreoptic bronchoscopy: problems in the histological classification of non-small cell carcinomas.

Specific cell typing in lung cancer has important implications for assessment of prognosis and the planning of treatment. Cell typing is, however, often difficult and the problem has been compounded by the universal use of the flexible fibreoptic bronchoscope, which yields specimens only 2 mm in diameter. We have reviewed the records of 107 patients who had a diagnosis of lung cancer established by fibreoptic bronchoscopy and who subsequently underwent staging biopsy or surgical resection. Examination of tissue obtained by surgical resection yielded a different cell type from that identified in specimens obtained at fibreoptic bronchoscopy in 11 of 32 patients with a bronchial biopsy specimen diagnostic of squamous cell, three of 44 patients with a diagnosis of adenocarcinoma, six of seven thought to have a poorly differentiated carcinoma, and 21 of 24 patients with a diagnosis of large cell carcinoma. In all, 41 of the 107 surgically removed specimens (38%) differed in cell type from their corresponding bronchoscopic specimens. Accurate cell typing by specimens obtained at fibreoptic bronchoscopy may be extremely difficult. If clearcut morphological criteria cannot be satisfied, the diagnosis of "lung cancer, non-small cell type" should be made.