HIGH-RESOLUTION ULTRASONOGRAPHY IN THE DIFFERENTIAL-DIAGNOSIS OF CYSTIC DISEASES OF THE KIDNEY IN INFANCY AND CHILDHOOD - PRELIMINARY EXPERIENCE

Autosomal recessive polycystic kidney disease, autosomal dominant poly cystic disease, and glomerulocystic disease may all appear in the peri natal period as bilaterally enlarged echogenic kidneys. Current ultras onographic equipment can better demonstrate the underlying pathologic state and assist in the differentiation of these conditions. The prima ry abnormality in autosomal recessive polycystic kidney disease is at the level of the collecting ducts, which are dilated and saccular. The nephrons remain normal. These dilated ectatic tubules are seen in the ir usual distribution as a radial array, with major ducts being perpen dicular to the renal capsule, in both the renal cortex and the medulla . The peripheral renal cortex does not normally contain collecting duc ts and remains unaffected in patients with mild disease. Autosomal dom inant polycystic disease is characterized by cystic changes involving both the nephron and the collecting ducts. The nephron may become cyst ic at any point. Multiple discrete cysts of varying sizes are seen in both the renal cortex and the medulla in the severely affected infant. Subcapsular cysts are seen regularly. Glomerulocystic disease is an u nusual sporadic condition characterized by the cystic dilation of the space of Bowman and the proximal convoluted tubule. On ultrasonographi c examination tiny, isolated cysts, usually smaller than those occurri ng in autosomal dominant polycystic kidney disease, are seen in the ec hogenic renal cortex and may extend to the periphery of the kidney. No cysts are seen in the renal medulla. Correlation between pathologic f indings and sonographic images is of value in correctly diagnosing the se conditions.