MALT1 Rearrangements in BAL Fluid.

We read with great interest the article by Kido et al 1 in an issue of CHEST (January 2012) demonstrating mucosa-associated lymphoid tissue (MALT) lymphoma translocation gene 1 rearrangements in BAL fl uid (BALF) in four of fi ve cases of pulmonary MALT lymphoma. The use of BALF is debated, but the authors elegantly demonstrate that BALF may be useful for the diagnosis of pulmonary disease, particularly when lymphoma is suspected. The authors report an elevated number of lymphocytes, median 30%, in BALF from patients with pulmonary MALT lymphoma, which did not differ from control samples (23.6%). However, the authors did not report the phenotype of the lymphocytes or the results of clonality analysis. Indeed, we previously reported, for a series of 44 patients, an increased proportion of lymphocytes in BALF (31.5%) and a median B-lymphocyte proportion (CD19 or CD20) of total alveolar lymphocytes of 20% (normally , 10%); moreover, clonality analysis of alveolar B cells showed a B-cell clone in 82% of the cases. 2 In a prospective study, specifi city and sensitivity of BALF clonality results were reported to be 97% and 95%, respectively. 3