Chest radiograph and CT were undertaken. Chest radiograph (Fig. 2a) showed a reticular pattern more pronounced in the central parts of the lungs. There was also an increase in lung density centrally in both lungs. No pleural fluid was noted, and the heart and central vascular structures were normal. On CT, there was a patchy distribution of areas with increased lung attenuation throughout both lungs. Superimposed on this increased lung attenuation a linear pattern was seen. There were multiple small regular and irregular lines. Some of them were thickened interlobular septa. More lines were visible in the centre of the secondary pulmonary lobule in a very irregular pattern suggesting thickening of the intralobular interstitium.