[Multilocular cystic nephroma in adults. Unusual presentation and review of the literature].

The authors report a case of a multilocular cystic nephroma in an unusual site, extensively invading the pelvis and causing atypical symptoms of acute lumbar pain. The authors discuss the confusing terminology, the unusual presentation of this cystic tumour and the difficulty of establishing a definitive diagnosis of its benign nature before the operation in the light of a brief review of the literature.