Does anyone have any information or experience with a complex kidney cyst in a child? My child has a complex cyst, about 1cm, that has one or two areas of septation. We were previously told by urologist and nephrologist that the cyst did not look at all concerning on the ultrasound and may in fact be a simple cyst, but an additional radiologist they asked advised it is in fact complex because of the septations and further imaging is needed.

We were told it cannot be classified using the Bosniak scale because this isn't used in children. But I have read otherwise online. Is it used for cysts in children?

Also interested in other experiences with this type of cyst in a child and or any statistics on the chance of malignancy or the likelihood of the cyst to change over time into something more serious (assuming it is found to not be a concern right now). ?

One of the nephrologists we talked to said he has actually never seen a complex cyst in a child. Are they very rare? I cannot find much information online at all.

Thank you for any information.
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replied June 10th, 2014
Welcome to e health forum.

Renal cysts occur in a variety of genetic diseases in adults and children, but ‎‎"simple renal cysts" are commonly observed in normal kidneys. They are so ‎common, it is difficult to consider them a disease. ‎

More and more people are being diagnosed with these lesions as we use more ‎medical imaging technology such as ultrasound, X-ray and CT scanning. Magnetic resonance imaging is especially useful for characterizing the inside of ‎a cyst that is indeterminate after ultrasound and CT. Serial MRI examinations ‎at three, six and 12 months are warranted in some patients.‎
In one survey of people undergoing ultrasound for evaluation of non-kidney-‎related problems, 15 percent of men and 7 percent of women aged 50 to 69 ‎had a renal cyst. ‎
One-third of men and 15 percent of women older than 70 had a renal cyst.‎

The initial radiologic appearance of most cysts determines what further ‎evaluation is needed. The physician needs to accurately distinguish simple ‎renal cysts from complex renal cysts. ‎

Simple cysts are round with a single wall, and in most cases do not require treatment. ‎

Complex cysts have walls within the outer wall or are a collection of small ‎cysts. These can harbor cancerous masses.‎

Many physicians use the Bosniak classification of renal cysts to determine ‎follow-up. ‎
Observation of lesions is far more common than biopsy.

Traditionally biopsy ‎required removal and loss of the kidney. ‎Biopsy can now be done with a needle through the skin using CT imaging to ‎guide the needle. These needle biopsies were once discouraged but are now ‎done in very specific circumstances.
Bosniak uses a complicated algorithm of CT scan characteristics such as size, ‎density and perfusion to place cystic renal masses into one of five different ‎categories. ‎

Bosniak categories I and II are generally simple cysts and do not require ‎further evaluation. Some would repeat an ultrasound at six to 12 months to ‎assure stability and a correct diagnosis.‎

Bosniak category IIF cysts are more complex and deserve follow-up imaging to ‎document stability. The absence of change over time supports benign disease, ‎while progression suggests a cancer. In one study with long-term follow-up of ‎‎42 patients with category IIF, two eventually developed more complicated ‎cysts that were found to be cancerous. Observation prevented many ‎unnecessary surgeries.‎

Most Bosniak category III lesions undergo surgical ‎removal and evaluation, as 40 percent to 50 percent will be cancer. ‎In some cases close follow-up with magnetic resonance imaging is recommended.

Category IV lesions require surgical removal of the ‎kidney. Approximately 85 percent to 100 percent of these are cancerous.

Greater than 90 percent of those diagnosed with renal cancer still confined to ‎the kidney are alive and disease-free five years after diagnosis. ‎Five year disease free survival is 60 percent to 70 percent for those whose ‎disease has grown outside the kidney. ‎Survival rates are very low if the disease has spread beyond the kidney.‎

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