Bronchiolar-cell carcinoma.

Abstract

Bronchiolar carcinoma is a recognized clinical and pathologic entity. The radiologic findings are not specific, but permit the consideration of the diagnosis in many cases. While it is undoubtedly true that the x-ray appearance is extremely varied, the findings are completely understandable if they are classified according to the stage of development of the tumor. In its behavior, location, and relatively benign histology, bronchiolar carcinoma is quite different from bronchogenic carcinoma. The authors are reporting 16 cases (Table I) to illustrate the various features of the condition. Cases of intrinsic bronchogenic carcinoma or with primary adenocarcinoma elsewhere in the body have been excluded. Synonyms: The most common synonyms for bronchiolar carcinoma are: alveolar-cell carcinoma, pulmonary adenomatosis, papillary adenocarcinoma, and mucous carcinoma. Others are: primary multiple carcinoma, multicentric papillary adenocarcinoma of the lungs, columnar-cell carcinoma, alveolar-cell tumor, malignant adenomatosis, and multiple nodular carcinoma. Still others are mentioned by Liebow (15). Definition: Bronchiolar carcinoma is a primary lung tumor probably originating in the terminal bronchioles (Herbut, 10) in the peripheral portions of the lung. It has a relatively benign histologic appearance and is composed of tall columnar or cuboidal mucus-secreting cells lying on an intact alveolar septum. It does not, as a rule, destroy the normal pulmonary tissue. We are making no distinction between this tumor and pulmonary adenomatosis. Etiology The etiology of bronchiolar carcinoma is unknown. It is a primary lung tumor with a distinctive histologic pattern and pathogenesis, setting it apart from other pulmonary neoplasms. Its relation to Jaagsiekte (probably a virus infection) in sheep, chronic inflammations (Beaver and Shapiro, 2), and possibly to irritating fumes such as smog and tobacco smoke, is of interest. None of these, however, has been established as the cause of bronchiolar carcinoma in man (Storey et al., 25). Pathology Gross: Small tumors are found in the peripheral portion of the lung. Rarely major bronchi may be invaded late in the course of the disease. There are no favorite sites; all lobes and either or both lungs may be involved. The tumors may be multiple or solitary, varying in size from those measuring a few millimeters in diameter to extremely large tumors involving the whole lung. A large mass may be present in one section and multiple small nodules may be found in another section or sections. The cut surface is moderately firm, gray-tan to yellow-brown in color. Mucus may exude from the cut surface. Nodular tumors may extend to the pleura. Pleural effusions may be present and be serosanguineous. Focal atelectases are not uncommon, but collapse of major bronchopulmonary segments, lobes, or a whole lung is rare.