Multiple foci of atypical epithelial hyperplasia (tumourlets) in irradiated human lungs.

Abstract

Small foci of atypical epithelial hyperplasia arising from respiratory bronchioles, alveolar ducts and alveolar epithelial cells have been named “tumourlets” by Whitwell (1955). They have been regarded as bronchial carcinoids or adenomas (Felton, Liebow and Lindskog, 1953; Prior 1953), early carcinomas (Petersen, Hunter and Sneeden, 1949; Stewart and Allison, 1943), and atypical hyperplasia, or metaplasia of bronchial and bronchiolar epithelium (Berkheiser, 1959; King 1954; Whitwell, 1955). Tumourlets have been described in lungs affected by bronchiectasis, chronic abscesses, fibrosis, nonspecific inflammation, anthracosis, and at the edge of old pulmonary infarcts (Evans, 1968). They have never been found in the absence of damage to the lung (Spencer, 1968). They have been produced experimentally in rabbits by the intratracheal instillation into the lungs of 1 per cent nitric acid, the animals being protected from the development of pneumonia by antibiotic cover (Totten and Moran, 1961). No reports describing the presence of tumourlets in irradiated lungs have been found in the literature. The finding of tumourlets in the lungs of a patient with multiple pulmonary metastases from malignant teratoma of the testis treated by radiotherapy, who has developed radiation pneumonitis, forms the basis of this report. The patient, a 37-year-old man, was admitted to hospital with possible torsion of his right testis at the beginning of November 1971. Two weeks previously he had noticed swelling of his right testis, which became increasingly painful.