Sonographically detected malignant transformation of a simple renal cyst

CEUS Bosniak Classification-Time for Differentiation and Change in Renal Cyst Surveillance

It is time for a change. CEUS is an established method that should be much more actively included in renal cyst monitoring strategies. This review compares the accuracies, strengths, and weaknesses of CEUS, CECT, and MRI in the classification of renal cysts. In order to avoid overstaging by CEUS, a further differentiation of classes IIF, III, and IV is required. A further development in the refinement of the CEUS-Bosniak classification aims to integrate CEUS more closely into the monitoring of renal cysts and to develop new and complex monitoring algorithms.

Single-Incision Laparoscopic Deroofing and Omentalization of a Cystic Renal Adenoma in a Dog

A 12 yr old 13.5 kg male castrated Pembroke Welsh corgi was presented for evaluation of a suspected renal cyst following multiple episodes of lethargy and abdominal pain. Abdominal imaging revealed a large, thin-walled, hypoechoic cystic lesion associated with the cranial pole of the left kidney and a second smaller cystic lesion on the caudal pole. The larger cystic lesion was repeatedly drained percutaneously, but the lesion returned to initial size and clinical signs returned within weeks. Percutaneous ethanol sclerotherapy achieved only transient improvement in lesion size and abdominal discomfort. Laparoscopic deroofing and omentalization of the larger left renal cystic lesion was performed. The resected cystic wall was histopathologically consistent with a renal adenoma. Abdominal ultrasonography performed 1 mo postoperatively found no recurrence of the cystic renal adenoma. Repeated ultrasonography at 3 mo postoperatively detected a small cystic lesion at the cranial pole of the left kidney, which remained static in appearance at 11 and 18 mo postoperatively. During all follow-up visits, the dog was reported to be doing well with no recurrence of clinical signs. Renal cysts causing clinical signs and renal adenomas are rare in veterinary medicine; laparoscopic deroofing and omentalization provides a minimally invasive treatment approach.

Partial nephrectomy for a Bosniak IV cystic renal mass mimicking a simple renal cyst adjacent to a solid renal tumor

INTRODUCTION

Renal tumors are often associated with renal cysts. Meanwhile, in some cases there are challenging issues of how to diagnose renal cystic tumors and to decide surgical procedures.

CASE PRESENTATION

A 75-year-old man was referred to our department for a 21-mm tumor by his left kidney. Contrast-enhanced computed tomography showed an intense contrast uptake the tumor, which was adjacent to a 64-mm unilocular renal cyst with no contrasting effects. It was clinically diagnosed as renal cell carcinoma, stage T1aN0M0, and treated with robot-assisted partial nephrectomy, for both the solid tumor and the adjacent cyst. Pathological findings revealed a tumor cell clump within the cyst wall, concurrent with the renal cell carcinoma. The patient has remained free of disease at 1 year after surgery.

CONCLUSION

A partial nephrectomy that includes the entire cyst wall should be considered for renal tumor associated with unilocular renal cyst.

Renal cell carcinoma originating in the free wall of simple renal cyst: Two unusual case reports with literature review

RATIONALE

Simple renal cyst (SRC) is a benign disease. However, rarely renal cell carcinoma (RCC) may be raised at the wall of a preexisting SRC. We herein describe 2 unusual cases of RCC arising from the outer surface of the free wall of the renal cyst.

PATIENT CONCERNS

A 75-year-old female and a male were admitted to our department because of an asymptomatic renal cystic mass. Although the case history, preoperative imaging, and intraoperative examination of the cyst were carefully evaluated, no concerns were raised with respect to the underlying malignancy.

DIAGNOSIS

RCC of the clear cell type was diagnosed based on the histology and pathological examination.

INTERVENTIONS

With an initial diagnosis of SRC, the retroperitoneal laparoscopic de-roofing of the SRC was performed in both of the patients. When the diagnoses were confirmed 7 days postoperative, both of them were readmitted to our department for a radical nephroureterectomy.

OUTCOMES

The postoperative course was uneventful and the two patients did not undergo further chemotherapy. They are currently well and have no clinical or radiological signs of recurrence.

LESSONS

Such cases remind us that seemingly benign renal cysts may harbor underlying neoplasia. Further evaluation and periodical follow-up are also recommended on the management of those seemingly benign renal cysts.

Renal cell carcinoma presenting as a simple renal cyst: A case report

Cases of renal cell carcinoma (RCC) presenting as a simple cyst are extremely rare. We herein report the case of a patient with RCC diagnosed as a simple renal cyst preoperatively. A 39-year-old female patient presented with abdominal pain for 3 months. Ultrasonography and contrast-enhanced computed tomography revealed a simple cyst in the left kidney. The patient underwent laparoscopic decortication of the renal cyst. Biochemical analysis of the cystic fluid revealed unusually low levels of potassium, sodium, calcium and glucose, and the histological examination of the floor of the cyst indicated malignancy. Laparoscopic nephrectomy was performed 20 days later and the pathological examination confirmed the diagnosis of RCC of the clear cell type. At the 2-year follow-up, the patient remained well and recurrence-free on imaging. The aim of the present study was to emphasize the importance of recognizing that RCC may occur in what appears to be a simple renal cyst based on imaging results. Biochemical analysis of the cystic fluid may help identify the presence of malignancy.

Influence of vascular endothelial growth factor inhibition on simple renal cysts in patients receiving bevacizumab-based chemotherapy

Purpose

Although angiogenesis has been implicated in the promotion of renal cyst growth in autosomal dominant polycystic kidney disease, no studies have investigated the role of angiogenesis in the growth of simple renal cysts. The aim of current study was to investigate the effect of chemotherapy with the antivascular endothelial growth factor antibody bevacizumab on renal cyst development and growth in cancer patients.

Materials and Methods

We retrospectively reviewed the medical records of 136 patients with a variety of cancers that were treated with bevacizumab-based chemotherapy for metastatic disease. The presence of and changes in renal cysts were evaluated by retrospective analysis of computed tomography scans performed for assessment of tumor response to bevacizumab-based therapy.

Results

The median age of the patients was 64 years. Renal cysts were identified in 66 patients, in whom 33 (50%) had a single cyst and the rest had 2 or more cysts. The average dose of bevacizumab was 2.68 mg/kg per week. Median duration of treatment was 33 weeks. Average cyst size was 1.9±2.4 cm at the beginning of the study and the majority of the cysts (54 patients, 84%) did not change in size or shape during bevacizumab treatment. No patients were identified with new cysts. Cyst size changed in 10 patients (16%): an increase of 15% to 40% from the baseline size in 5 patients and a decrease in size of 10% to 70% in another 5 patients. The duration of bevacizumab therapy was significantly longer in the subgroup of patients with diminished or increased cyst size than in the patients with stable cyst size: 62 weeks versus 29 weeks, respectively (p=0.0002).

Conclusions

Our data demonstrated that simple renal cysts were stable in size and number in the vast majority of cancer patients treated with bevacizumab.

How simple are 'simple renal cysts'?

The increasing use of medical imaging as an investigative tool is leading to the incidental and frequent finding of renal cysts in the general population. The presence of a solitary or multiple renal cysts has been generally considered benign in the absence of a family history of renal cystic disease or evidence of chronic kidney disease. Nonetheless, a number of recent studies have questioned this consensus by reported associations with the development of hypertension or malignant change. For these reasons, some clinicians consider the presence of renal cysts to be a contraindication to kidney donation. The situation is complicated by the different usage of the term 'simple' by some radiologists (to indicate non-complex lesions) or nephrologists (to indicate age-related non-hereditary lesions). We propose that the term 'simple' be replaced with the morphological description, Stage I renal cyst (Bosniak Classification). The presence of a Stage I renal cyst should not preclude kidney donation. However, occult renal disease should be excluded and appropriate donor assessment performed.

Complicated variation of simple renal cyst usually means malignancy: results from a cohort study

BACKGROUND

Currently, simple renal cysts (SRCs) are not considered to warrant follow-up or specific treatment unless a patient presents symptomatically. By demonstrating malignant transformation of SRCs, we urge regular follow-up and timely surgical treatment in affected patients.

METHODS

From September 2002 to September 2010, we treated 31 cases of renal cell carcinoma derived from SRCs. Among these patients, in 14 cases a SRC was radiographically detected by computed tomography (CT) or magnetic resonance imaging (MRI) prior to operation, and malignant tumors were detected by pathological analysis following laparoscopic cyst decortication; 13 of these patients received supplementary radical nephrectomy within 2 months, whereas one patient chose to receive active surveillance. The other 17 patients exhibited SRCs and were monitored by ultrasound for over 6 months; surgical treatment was chosen if a complicated variation of SRCs was found during surveillance, detected by ultrasound, and confirmed by CT or MRI. Median follow-up was 60 months (30 to 126 months). All data analyzed were collected with informed consent, and the study was approved by the ethical committee of our institute.

RESULTS

Pathological studies confirmed early-stage clear-cell renal cell carcinoma in all of the cases, with Fuhrman grade I to III. In decortication-detected malignancies, supplementary radical nephrectomy exhibited residual tumor in 7 out of 13 cases; the patient who chose active surveillance remains free of recurrence for 78 months, and all other patients survived without disease at the last follow-up.

CONCLUSIONS

Renal cell carcinoma may be detected incidentally in SRCs, and more attention should be paid to complicated variations of SRCs during surveillance, owing to the extremely high probability of malignancy. This interesting but alarming phenomenon might urge regular follow-up and timely surgical treatment in affected patients.

Unexpected outcome after sclerotherapy of simple renal cyst

Background

Simple renal cysts usually have benign clinical features. We report a rare case of papillary renal cell carcinoma (RCC) associated with a large recurrent simple cyst following sclerotherapy.

Case Presentation

A 47-year-old Japanese woman received minocycline sclerotherapy for a large (9 cm in diameter) simple left renal cyst in May 2005. The cyst regrew, and second-line sclerotherapy with ethanol was performed in November 2005. Three years later, she developed papillary RCC on the wall of the recurrent renal cyst. Radical nephrectomy was performed, but the patient died of metastatic disease 15 months after surgery.

Conclusion

Malignant transformation from recurrent simple renal cyst to RCC may occur in the years following sclerotherapy, underscoring the need for long-term follow-up.

Renal cysts in living donor kidney transplantation: long-term follow-up in 25 patients

INTRODUCTION

The acceptance of a living donor kidney bearing cysts might implicate complications after the transplantation due to the natural history of renal cysts. We have presented our experience with transplantation of living donor kidneys containing cysts but not polycystic disease.

PATIENTS AND METHODS

We retrospectively reviewed donor and recipient records of all living kidney transplants performed between January 1997 and April 2008. We analyzed serum creatinine and urea levels, as well as ultrasound scans concerning cyst size and morphology at hospital discharge as well as at 12 and 24 months after transplantation.

RESULTS

Among 268 living kidney transplantations, we noted 25 donors with renal cysts. In the computed tomography scan reports, 19 kidneys were described to show a single and six, multiple cysts. The size of 10 single cysts was <5 mm; the other nine were a mean of 17.33 mm. Two of the multiple cyst kidneys had lesions <5 mm; in four kidneys, the mean cyst size was 27.25 mm. The renal function of the recipients was normal or almost normal at discharge with a tendency to lower levels at 12 and 24 months after transplantation. Ultrasound revealed changes in cyst diameter among 6/23 kidneys; the mean diameter increased after 12 months, namely, 8.25 mm to 11.5 mm after 24 months. The subgroup of patients with enlarged cysts showed creatinine and urea levels slightly higher than in the entire group. No aspects of malignancy were found, according to the Bosniak and Israel classification system. One suspicious cyst was tomographically confirmed to be hemorrhagic without any need for treatment. None of the living donors had any problems related to the donor nephrectomy or a need for dialysis due to renal insufficiency in the long term. In addition, the living donors who had even beforehand cystic lesions in their contralateral nonremoved kidney at the time of transplantation did not show complications upon follow-up.

CONCLUSIONS

In our study, 25 living donor kidneys carried cysts. Neither cyst-related complications nor dysfunction of the transplanted organs occurred. An unroofing or excision of the cyst was generally not necessary. Regular ultrasound scans and optional computed tomography scans are recommended for follow-up. Based on this experience, we concluded that kidneys presenting cystic diseases should be considered to be suitable for transplantation without a hazard to the recipients, thus extending the pool of organs.

Incidental Findings During Routine Antepartum Obstetrical Sonography

The standard for performing an antepartum obstetrical sonogram primarily involves the examination of the fetus; however, both the American Institute of Ultrasound in Medicine (AIUM) and American College of Radiology (ACR) guidelines suggest the evaluation of maternal structures as well. The authors present 35 incidental findings that were discovered on routine antepartum obstetrical sonography. These include abdominal wall, gastrointestinal, reproductive, urinary, and vascular anomalies in the maternal structures. A review of the literature demonstrates that many of these findings have clinical significance, which highlights the wisdom of the AIUM and ACR guidelines, and it also stresses the importance of seeking and reporting them.

The 10-year natural history of simple renal cysts

OBJECTIVE

We previously reported the natural history of renal cysts, with a mean follow-up of 6 years. Here, we extended the follow-up period to 10 years.

METHODS

From January 1993 to August 2006, 61 patients diagnosed with renal cysts were followed for up to 14 years (mean 9.9 years). The sequential changes in renal cyst size were plotted against patient age, and the rate of increase in cyst size per year was calculated for each individual. Those cyst characteristics known to predict aggressiveness were analyzed.

RESULTS

The majority of the cysts increased in size and number. The average size increase and the average rate of enlargement in all cysts were 1.6 mm and 3.9% per year, respectively. Several cysts, especially multiloculated cysts, increased rapidly during the first 2 to 3 years, but then the rate of growth tended to decelerate with time. By using univariate analyses, age, laterality and cyst shape were revealed to be significant predictors of aggressiveness. The multivariate analysis revealed that age was the most significant predictor. Renal neoplasms originating from the renal cysts appeared in 2 patients during the follow-up period. The rate of size increase of the neoplasm-bearing cysts was similar to that of the other benign renal cysts in the same age category.

CONCLUSIONS

The simple renal cysts continued to increase in size over 10 years, and sometimes increased rapidly, especially in younger patients. However, their growth rates appeared to decrease with age. There seems to be no specific pattern observed in the neoplasm-bearing renal cysts.

Renal cell carcinoma presenting as a huge simple renal cyst

Simple renal cysts are the most common renal masses, accounting for roughly 65-70% of cases. Transformation of a simple renal cyst into a renal cell carcinoma (RCC), however, is extremely rare. We reported a 48-year-old man with a right huge simple renal cyst from which about 800 ml of dark yellowish fluid with elevated protein and lactic dehydrogenase (LDH) levels was aspirated. Cytological examination disclosed negative for malignant cells. Nephrectomy was performed because of intractable flank pain 3 months after aspiration. The pathology examination confirmed RCC. While this is an extremely unusual finding, one must not exclude the possibility of malignancy in an apparently simple cyst.

Renal cell carcinoma: unusual imaging manifestations

Unusual radiologic manifestations of a renal cell carcinoma (RCC) can present a diagnostic challenge. These manifestations include bilateral synchronous multifocal tumors, a small RCC with synchronous adrenal metastasis, and RCC associated with bulky abdominal lymphoma. Less common manifestations include multiseptated cystic carcinoma simulating a moderately complex renal cyst at ultrasonography (US), paraaortic metastatic adenopathy as the only sign of an undetectable primary renal neoplasm, RCC causing a large arteriovenous fistula, RCC simulating angiomyolipoma, and a nonfunctioning kidney due to transparenchymal renal propagation of cancer associated with a tumor thrombus occluding the renal vein. Radiologists should be aware of the possibility of tumor multifocality or of adrenal metastases from a high-grade small renal tumor, as well as of the association of RCC with lymphoma. They should also be aware of the importance of following up a multiseptated cystic mass found at US or a Bosniak category IIF renal cyst, since these lesions can serve as early indicators of cystic carcinoma. Because the clinical implications of and therapeutic strategies for RCC vary depending on imaging characterization of the nature and extent of the disease, familiarity with its more unusual radiologic manifestations facilitates accurate diagnosis and management.