LETTERS TO THE EDITOR Vibration during high frequency ventilation in neonates

usefulness of HRCT scanning for diagnosis of this disease. Other previously reported CT findings of the disease include increased soft tissue density of the mediastinum 2 and mediastinal and hilar lymph adenopathies, but such findings were absent in our case. Possible explanations for the stable condition of our case over a long period are either that it was a chance discovery of an early phase of the disease by HRCT scanning or that PCH has separate subtypes with diVering speeds of progression. Wider use of HRCT scanning and more extensive understanding of PCH would resolve this issue in the future.