Polycystic disease of the kidney, according to some authors, is always bilateral.1 Others state that it may be unilateral.2 In the bilateral form, which in some instances seems to have a hereditary tendency, there appear to be two types: (a) the more frequent adult form, characterized by replacement of renal parenchyma and distortion of the collecting tubules due to large cysts, with death usually occurring in the fifth to sixth decade; (b) the infantile form, in which small cysts are present throughout the parenchyma and replacement of renal tissue leads to early death of the patient.
A unilateral variety which is said to be congenital has been described in both adults and children. In some of these cases of presumed unilateral polycystic disease there has been postmortem confirmation3,4; in others, further study has demonstrated that the involvement was actually bilateral.5 A review of the literature shows
MENASHE V, SMITH DR. Apparently Unilateral Polycystic KidneyA Cause for Abdominal Calcific Shadows. AMA Am J Dis Child. 1957;94(3):313-317. doi:10.1001/archpedi.1957.04030040099015