Localized ground glass opacities with multiple pulmonary small cysts in adult T-cell leukemia or lymphoma: an "alloy wheel" appearance.

We herein report a case of adult T-cell leukemia or lymphoma showing multiple lung cysts within a localized ground glass opacity (GGO) on computed tomography scan. The patterns of multiple localized GGOs having multiple small cysts were varied, including a large air space in the center of the localized GGO with surrounding small cysts, a solid part in the center of the localized GGO with peripheral small cysts, and clustered small cysts. These findings were considered to simulate the appearance of an "alloy wheel." Some of the central large air spaces had thickened walls. On the basis of the histopathologic findings, the pathogenesis of multiple cyst formation was considered to be a combination of 2 main mechanisms as follows: a check valve mechanism due to stenosis or an obstruction by the tumor cells' infiltration along the bronchioles, traction bronchiolectasis and ectatic alveoli by fibrosis.