Cystic nephroma (CN) is a benign cystic tumor of the kidney. Children with DICER1 variation are at elevated risk for development of these tumors. Risk for development of CN is highest in the first 4 years of life, however, development of CN has also been noted in older children and adolescents with DICER1 variation.
Isolated renal cysts are also more common in individuals with DICER1 variation.
Cystic nephroma may grow rapidly and cause concern for mass effect on normal functioning kidneys, a particular concern in bilateral tumors. Although benign, rare cases of cystic nephroma with progression to renal sarcoma, a malignant tumor, have been described.
In addition, children or young kids with germline DICER1 variation may rarely develop renal sarcoma or DICER1-related Wilms’ tumor with no preceding history of cystic nephroma.
The most common symptom is painless abdominal or a mass located on the sides of the abdomen. Abdominal or flank pain or hematuria may be noted.
On ultrasound, computed tomography (CT or CAT) and/or MRI, cystic nephroma appears as one or multiple cystic masses arising from the kidney.
Treatment for cystic nephroma consists of surgical resection via partial or full nephrectomy. Generally chemotherapy is not given for cystic nephroma alone, however, the use of chemotherapy has been considered in rare cases with extensive bilateral disease and continued rapid growth.
Treatments for renal sarcoma and Wilms tumor generally includes chemotherapy with or without radiation. Please contact the Registry for additional information.
Individuals and families should be counseled regarding potential symptoms of DICER1-related kidney tumors. For individuals with germline pathogenic DICER1 variation, we recommend ultrasound every 6 months until age 8 and annually until age 12. For a complete copy of surveillance guidelines for individuals with DICER1 variation, please contact the Registry.
Differential diagnosis for cystic renal tumors includes:
Isolated renal cysts are common in the general population, and the prevalence rises with increasing age. Simple renal cysts and cystic renal dysplasia are most commonly seen in children. Birt-Hogg-Dube syndrome is also associated with renal cysts, oncocytoma, and chromophobe renal cell carcinoma. None of these latter lesions are known to be associated with PPB. Multiple renal cysts may also be seen in von Hippel Lindau syndrome. There are also infant and adult types of polycystic kidney disease.
CN may grow rapidly and cause concern for mass effect on normal functioning kidneys, a particular concern in bilateral tumors.
A small number of children with CN and a DICER1 germline mutation have later developed high grade renal sarcomas resembling PPB. This sarcomatous transformation in the kidney may be similar to the transformation in the lung. Additionally, a subset of Wilms tumor, the most common kidney tumor of childhood, is related to DICER1 variation.