Outcome after right middle lobe syndrome.

The long-term pulmonary consequences of right middle lobe syndrome (RMLS) in childhood are not known. Therefore, outcome was evaluated in 17 children with RMLS diagnosed in early childhood (mean age, 3.3 years; SD, 1.1 year). Mean age at follow-up was 10.1 years (SD, 2.6 years). RMLS was defined as atelectasis of the right middle lobe (RML) of at least 1 month's duration and visible on the lateral view of the chest radiograph as a wedge-shaped density extending from the hilum anteriorly and downward. Seventeen children without personal history of allergy or respiratory tract disease were studied as control group. Five of 17 study group children had ongoing respiratory problems: symptoms of asthma were present in 4 patients, and cylindrical bronchiectasis was present in one patient. Chest radiograph at follow-up was abnormal in six patients. Pulmonary function tests, including mean and SEM for vital capacity (VC) (82% of predicted +/- 7 vs 94% predicted +/- 3), FEV1 (77% of predicted +/- 12 vs 96% of predicted +/- 4) and their ratio (75 +/- 5 vs 85 +/- 3) were significantly lower in patients with ongoing respiratory symptoms than in the control children. The provocative dose causing a 20% decrease in FEV1 (PD20) of methacholine was significantly lower in patients with ongoing symptoms at follow-up than in control children and in patients without symptoms at follow-up (2.8[2.2 to 3.1] vs 4.5[2.2 to 8.8] and 9.2[2.3 to 24] mg/mL; median and P25-75, p < 0.05). Age at initial diagnosis tended to be younger in patients with ongoing symptoms at follow-up (2.3 +/- 0.7 years vs 3.8 +/- 0.4 years; p < 0.08).