Prepared by Jeanne G. Hill, MD, of the Department of Radiology
at the Medical University of South Carolina, Charleston, SC.
A 4-year-old previously healthy white boy presented to his
pediatrician with a history of intermittent gross hematuria. He had
no immediate prior history of trauma or abdominal pain. His
physical examination was un-remarkable. Laboratory evaluation at
that time was significant for microscopic hematuria on urin-alysis.
Renal ultrasound exam-ination and abdominal CT were performed
(figures 1 and 2). The patient was referred to a surgeon. Despite
medical advice, surgery was delayed at the parents' insistence.
Three weeks after initial presen-tation, the patient returned with
acute right abdominal and flank pain. A repeat abdominal CT was
followed by laparotomy (figures 3 and 4).
Multilocular cystic nephroma
Imaging reveals a focal collection of uncomplicated cysts
deforming the contour of the right kidney. The cysts do not appear
to communicate with each other or with the renal pelvis. The septae
between the cysts are smooth and regular. The development of
obstruction in the involved kidney was secondary to the passage of
a clot, noted as a filling defect on the initial CT image,
The differential diagnosis of this lesion includes a cystic
partially differentiated nephroblastoma (predominantly cystic
Wilm's tumor), and congenital mesoblastic nephroma. The former
occurs in the same age group and cannot be differentiated
conclusively from a multilocular cystic nephroma by any imaging
modality. The latter, a benign mesenchymal neoplasm, is usually
solid (but rarely may be cystic) and detected in the first 3 months
of life. Although there are other primarily cystic renal neoplasms,
multilocular cystic renal cell carcinoma and cystic hamartoma of
the renal pelvis, these entities are exceedingly rare in the
pediatric population. Unilateral focal autosomal dominant
polycystic kidney disease, also a very rare entity, could have a
similar imaging appearance and family history would be vital to
making this diagnosis.
Multilocular cystic nephroma is an uncommon, usually benign,
renal neoplasm characterized by a well-encapsulated mass of
noncommunicating, fluid-filled locules separated by thin
Since its initial description in 1892, a variety of terms have been
applied to this lesion causing a great deal of confusion about this
entity. Over the years, it has been considered a developmental
lesion, a form of renal dysplasia, a hamartoma, and now, as
initially, a neoplasm.
It has a bimodal age and sex distribution, affecting boys from 3
months to 4 years of age, and women over 30 years of age.
The tumor usually presents as a non-painful abdominal mass in
children. Gross hematuria, may be seen at all ages and is
associated with herniation of tumor into the renal pelvis.
The tumor is usually unilateral but may be multiple and bilateral.
Madewell JE, Goldman SM, Davis CJ Jr., et al
: Multilocular cystic nephroma: A radiographic-pathologic
correlation of 58 patients. Radiology 146:309-321, 1983.
Eble JN, Bonsib SM:
Extensively cystic renal neoplasms: Cystic nephroma, cystic
partially differentiated nephroblastoma, multilocular cystic renal
cell carcinoma, and cystic hamartoma of renal pelvis. Sem Diag
Pathol 15(1):2-20, 1998.