In Langerhans cell histiocytosis (LCH) pulmonary involvement, which is often initially asymptomatic, may contribute to significant morbidity and mortality. To determine the long‐term prognosis, a cross‐sectional study was undertaken.

Forty‐one patients with ≥5 years follow‐up after the diagnosis of LCH were interviewed and underwent physical examination, blood tests, a chest X‐ray and a high‐resolution CT (HRCT) of the lungs. All patients included had been referred to the Department of Pediatrics at the Karolinska Hospital in Stockholm between July 1962 and February 1990 (median follow‐up 16 years). Biopsies from all patients were reviewed and confirmed to be consistent with LCH. Information on previous clinical features including treatment and the results of chest X‐rays were also collected for risk factor analysis.

Radiographic abnormalities of the lungs (cysts and/or emphysema), found in 10/41 (24%) at follow‐up, were classified into five groups according to the extent of the cysts. These patients had more often suffered from multisystem than from single‐system disease (P = 0.01), were significantly older at diagnosis (P < 0.001), and had been more heavily treated with chemotherapy and/or radiotherapy. They were also more frequently smokers (P < 0.0001) and 7/10 (70%) had suffered lung involvement at diagnosis. At the time of diagnosis of the pulmonary involvement, 4/10 (40%) patients had respiratory symptoms, but only 2/10 (20%) had symptoms at follow‐up.

Ten (24%) of the 41 patients had abnormal findings on radiological examination of the lungs at long‐term follow‐up and seven are or had been smokers. It is of great importance that patients with LCH be informed about smoking‐related pulmonary morbidity. Prolonged monitoring of the lungs for smokers and patients with known pulmonary involvement is recommended. Med. Pediatr. Oncol. 36:459–468, 2001. © 2001 Wiley‐Liss, Inc.