The purpose of this study was to evaluate the radiologic features of Hot Tub Lung disease.
The CT scans of 15 patients (13 high resolution and 2 conventional CT scans) were evaluated for the distribution and extent of nodules, irregular lines and ground glass attenuation.
Nodules were present in 11/15 cases. They were bilateral and symmetric in 9 and bilateral and asymmetric in 2. In 9 cases there was a diffuse distribution of the nodules in the cephalocaudal plane with a centrilobular distribution in the transaxial plane. In the other 2 cases, the nodules had an upper lung distribution in the cephalocaudal plane and a random distribution in the transaxial plane. In 5 cases the nodules were well-defined and in 6 cases poorly defined. Ground glass attenuation was seen in 11/15 cases, and was bilateral and symmetric when present. The ground glass attenuation was diffuse in the cephalocaudal plane with a random distribution in the transaxial plane in 10/11 cases. In the other 1 case the areas of ground glass attenuation had lower lung predominance with a random distribution in the transaxial plane. In 6 cases the areas of ground glass attenuation involved >40% of the lungs and in 5 involved < 40% of the lungs. Both the nodules and ground glass attenuation were present in 7 cases (nodules only were present in 3 patients; ground glass only present in 3 patients). One patient had nodules, areas of ground glass attenuation and irregular linear opacities. Irregular linear opacities were present in only 1 case. They were bilateral and asymmetric with a subpleural and lower lung predominance and involved <10% of the lungs. In 7 cases expiratory images were obtained and all showed evidence of air trapping.
The patterns of centrilobular nodules, ground glass attenuation and air trapping are very similar to findings of subacute hypersensitivity pneumonitis.
In cases where the CT findings suggest hypersensitivity pneumonitis, hot tub lung should also be a diagnostic consideration.
Viktor Hanak, None.