The patient reports and review of the literature presented by Hartman et al1 clearly document that multicystic kidneys are not always persistent asymptomatic masses. Clearly, they can be associated with significant morbidity. The natural history of retained multicystic kidney is, as the authors state, unclear, since most palpable multicystic lesions have been removed in the past. However, available data indicate to me that untoward events associated with retaining such dysplastic renal units are quite rare, and, therefore, a blanket recommendation for routine removal of all such lesions seems extreme.
At our hospital in recent years, prenatal ultrasound examinations have identified multicystic kidneys that are not palpable at birth. In addition, our experience and that of others (E. Tank, MD, telephone conversation, Jan 15, 1986) suggest that some lesions that are palpable at birth shrink to minimal proportions when followed up for several months sonographically. Thus,