Nodular lesions in renal tuberculosis.

We retrospectively studied the CT findings of renal tuberculosis in 27 cases (32 kidneys). As a characteristic CT finding, nodular lesions were recognized in 20 kidneys. Low density nodules were found in three kidneys, isodensity nodules in seven, and high density nodules in 10. In a case examined by follow-up five years later, the low and isodensity nodules changed to high density nodules with decreasing volume. Ultrasound demonstrated the high density nodules as low-echo mass lesions. These nodular lesions corresponded with the localized foci in the renal parencyma and/or pyocalyx. We consider that the density differences in nodular lesions reflect the process of water absorption from the caseous necrotizing materials of tuberculosis.