Adenocystic carcinoma and mucoepidermoid carcinoma of the tracheobronchial tree.

ronchogenic carcinoma causes most of the morbidity and mortality associated with neoplasms of the lower respiratory tract. The term "bronchial adenoma" has been used to describe a small subgroup which comprises about 1.5 percent of all neoplasms of the lower respiratory tract.'p2 The value of the term "bronchial adenoma" lies in its gross descriptive classification of a group of primary endobronchial tumors with similar clinical features which differ significantly from those of bronchogenic carcinoma. Their relative incidence is rare, their sex distribution is equal if not more common in women. They tend to be located in the proximal portions of the tracheobronchial tree and symptoms are frequently of many years' duration. Three subgroups of bronchial adenoma are now generally recognized. The carcinoid variety accounts for about 85 percent of all bronchial adenoThe clinical features, treatment, pathology and malignant potential of the more common carcinoid type of bronchial adenoma, have been the subject of many reports in the literature and will not be considered further in this paper. Adenocystic carcinomas or cylindromas comprise about 10 percent of the so-called bronchial adenomas and the mucoepidermoid carcinomas the remaindera6 Smetma and co-workers7 in 1952 are generally credited with the first description of the mucoepidermoid carcinoma although they considered it a form of cylindroma. Two additional cases were added by LiebowB in the same year also as variants of cylindroma. As additional cases have accumulated, mucoepidermoid carcinomas have been separated and are now generally felt to be a distinct subgroup of bronchial a d e n ~ m a s . ~ . ~ . ~ ' ~ With the increasing recognition of the malignant potential of cylindromas, the term adenocystic carcinoma has been used synonymously in recent year^.^.'^,'^ Recognizing the rarity of these two tumors, it was felt worthwhile to report three additional cases recently seen at the Kansas City Veterans Administration Hospital (KCVAH).