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BackgroundPulmonary mucoepidermoid carcinoma (PMEC) and pulmonary adenoid cystic carcinoma (PACC) are the two major types of primary salivary gland-type (PSGT) lung cancers. The demographic profile, clinicopathological features, and predictors of survival as an overall group have not been described for PSGT cancers of lung.MethodsIn this study, we analyzed demographic, clinical, and survival data from 1,032 patients (546 PMEC and 486 PACC) who were diagnosed of PSGT lung cancer in the Surveillance, Epidemiology and End Results database from 1973 to 2014.ResultsThe PSGT constituted 0.09% of all lung cancers with age-adjusted incidence rate of 0.07 per 100,000 person-years and change of −32% from 1973 to 2014. The incidence of PMEC was slightly higher than PACC but there were no differences in the age and sex distribution. PACCs (55%) were significantly higher at trachea and main bronchus while PMECs were more common at peripheral lungs (85%). Most of the tumors were diagnosed at an early stage and were low grade irrespective of histology. As compared to PMEC, significantly higher number of patients with PACC underwent radical surgery and received adjuvant radiation. The 1- and 5-year cause-specific survival was 76.6 and 62.8%, respectively. On multivariate analysis, the survival was affected by age at diagnosis, tumor stage, histological grade, period of diagnosis, and surgical resection. The histology showed strong interaction with time and hazard ratio of patients with PACC was significantly worse than patients with PMEC only after 5 years.ConclusionThe incidence of pulmonary PSGT cancer is 7 cases per 10 million population in the United States and is decreasing. There was no difference between demographic profile of patients with PMEC and PACC but pathological features were diverse. The difference in the survival of patients with the two histological types surfaced only after 5 years when survival of patients with PMEC was better than PACC.

Pneumocystis carinii organisms cluster in alveolar casts. A method for concentrating alveolar casts in sputum specimens might improve the diagnostic usefulness of sputum studies in possible cases of pulmonary infection with Pneumocystis carinii. The use of sputum induction to detect Pneumocystis carinii was studied in 40 consecutive patients with known or suspected human immunodeficiency virus infection having bronchoscopy for evaluation of pulmonary disease. Sputum produced by deep coughing induced by 3% saline via a jet nebulizer was liquefied with dithiothreitol, and cells were sedimented and stained. Liquefaction of mucus allowed concentration of alveolar casts where P. carinii cysts were readily identified. A total of 28 patients were found to have P. carinii, which was detected in concentrated sputum in 21 of 38 patients, unconcentrated sputum in 10 of 38 patients, and by bronchoscopy in 25 of 37 patients. Sensitivity of concentrated sputum compared with bronchoscopy was 78% (95% CI, 58 to 90), with a negative predictive value of 71% (95% CI, 47 to 87). Values for unconcentrated sputum were 43% (95% CI, 25 to 63) and 48% (95% CI, 30 to 67), respectively. Liquefaction of adequately induced sputum facilitates processing and interpretation and increases yield for P. carinii, eliminating the need for invasive procedures in most patients.

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