[Computed tomography of adrenal Cushing's adenoma--CT-pathological correlation]

CT findings of 22 patients with surgically confirmed adrenal Cushing's adenomas were compared with pathologic findings. The cut surfaces of the adenomas showed mixture of yellow and brown areas in various proportions and were classified into three patterns; speckled brown areas in yellow background, geometrically brown areas in yellow background, totally brown or black surface. The maximum diameters of the cut surfaces were measured. The CT appearances of Cushing's adenomas after intravenous contrast administration have various patterns of enhancement and classified into three patterns; speckled, geometrical, and homogeneous. The maximum diameters of the adenomas in CT images were also measured. Correlation between the CT and gross appearances of the specimens showed that while brown areas in adenomas were strongly enhanced, yellow areas were poorly enhanced. Histologically, brown areas in adenomas consist of compact-like cells with rich intercellular space and yellow areas consist of clear-like cells with poor intercellular space. The patterns of contrast enhancement seem to depend on the cell types of adenomas. Difference in the intercellular space between compact and clear-like cells may have altered the patterns of contrast enhancement. The study also revealed that predominantly brownish adenomas were smaller in size than predominantly yellowish ones. As compact-like cells which make up the brown areas in Cushing's adenoma are thought to be more active in producing and secreting steroid hormones than clear-like cells, this result suggests that clinical symptoms may appear earlier in predominantly brownish adenomas than in predominantly yellowish ones.