Methods: English-language articles published up to November 2013 were systematically searched through PUBMED, EMBASE, and other databases. Adult patients with a proven diagnosis of MTX-P and careful mention of each BAL parameter were examined.
Results: Seventeen articles for a total of 47 patients were included. Four BAL patterns with a variably combined lymphocytosis and two with prominent neutrophilia were identified. A more intense lymphocytosis (P=0.004) and a more depressed CD4/CD8 ratio (P=0.01) were found in cancer patients compared with rheumatoid arthritis patients.
Conclusions: In MTX-P, cytological analysis of BAL may disclose up to six different patterns. In MTX-P affecting cancer patients, BAL tends to show the typical features of hypersensitivity pneumonitis, while, in rheumatoid arthritis patients, it is more heterogeneous, with a less intense lymphocytosis, a more pronounced neutrophilia, and a higher CD4/CD8 ratio. These differences could be related to a disparity in baseline pulmonary conditions between the two background diseases, i.e., to the presence of previously healthy lungs in cancer patients, and lungs already involved by the immune-mediated inflammatory processes, often not manifestly, in rheumatoid arthritis patients.