Reactive type II pneumocytes in bronchoalveolar lavage fluid

OBJECTIVE: To evaluate the prevalence of reactive type II pneumocytes (RPII) in bronchoalveolar lavage (BAL) fluid samples obtained from patients with various pulmonary disorders. STUDY DESIGN: Consecutive BAL fluid samples were screened for the presence of RPII on May-Grünwald-Giemsa-stained cytocentrifuge preparations. BAL fluid samples with and without RPII were compared with regard to prevalence, associated clinical diagnoses and cytologic findings. RESULTS: RPII were generally large cells with a high nuclear:cytoplasmic ratio and deeply blue-stained, vacuolated cytoplasm. Most RPII occurred in cohesive cell groups, and the vacuoles tended to be confluent. Cytologic findings associated with RPII were foamy alveolar macrophages, activated lymphocytes and plasma cells. RPII were present in 94 (21.7%) of 433 included BAL fluid samples. The highest prevalences were noted in patients with systemic inflammatory response syndrome and alveolar hemorrhage. In addition, RPII tended to occur more frequently in ventilator-associated pneumonia, Pneumocystis carinii pneumonia, extrinsic allergic alveolitis and drug-induced pulmonary disorders. In contrast, RPII were not observed in BAL fluid samples obtained from patients with sarcoidosis. CONCLUSION: RPII were prevalent in about 20% of BAL fluid specimens. They were associated mainly with conditions of acute lung injury and not observed in sarcoidosis.