Analysis of 10 cases of cystic kidney cancer
Zhao Pengcheng, He Zhaohong, Ren Junkai, Yang Tiejun, Feng Chaojie, Li Jing
Department of Urology, Henan Cancer Hospital 450003
Abstract】 Objective To investigate the diagnosis and treatment of cystic kidney cancer (CRCC). Methods A retrospective analysis of the clinical, ultrasound and CT characteristics, surgical approach and prognosis of 10 patients with cystic kidney cancer was performed. Two cases were diagnosed with cystic kidney cancer by preoperative ultrasound; six cases were diagnosed with cystic kidney cancer by CT, and two cases were diagnosed with renal cysts, which could not be excluded from the tumor, and intraoperative freezing indicated renal cell carcinoma. All 10 cases underwent radical nephrectomy. All 10 cases underwent radical nephrectomy and no recurrence was observed from 6 months to 4 years of follow-up. Conclusion Familiarity with the imaging characteristics of cystic kidney cancer is the key to improve the diagnosis rate of cystic kidney cancer. He Zhaohong, Department of Urology, Henan Cancer Hospital
【Key words】 Cystic renal cell carcinoma, diagnosis, treatment
Diagnosis and Treatment of 10 Cases of Cystic Renal Cell Carcinoma
[Abstract] Objective To study the diagnosis and therapy of cystic renal cell carcinoma (CRCC) . Methods Review historical document retrospective analysis was going on 10 cases of the cystic renal cell carcinoma from May 2006 to December 2010 about clinical features, images characteristics, prognosis and approach of surgery.
Results In the 10 cases of cystic renal cell carcinoma, 2 cases were diagnosed by ultrasonography and 6 by CT preoperatively ,other 2 cases were not diagnosed confirmly preoperatively, frozen Radical nephrectomy was performed in 10 cases .All have been followed up for 6months t o 4 years and have not recurrence. Conclusion Understanding of the characteristics of imaging of cystic RCC is the key to improve the diagnosis of cystic RCC. Key words】 Cystic renal cell carcinoma；Diagnosis；Treatment Renal cell tumors account for 80%-85% of primary malignancies of the kidney and usually present as solid masses; however, imaging studies have shown that a proportion of renal cell carcinomas present as unicellular cysts or multicellular cysts. The pathological histology of cystic RCC can be formed in 4 ways: unicompartmental intracapsular growth type (papillary cystic adenocarcinoma), multicompartmental intracapsular growth type, tumor cystic necrosis type (pseudocyst), and simple renal cystic malignancy type. Cystic renal carcinoma accounts for about 5-7% of solid renal tumors [1], and accurate determination of the benignity and malignancy of complex renal cysts is a problem frequently encountered by clinicians. However, imaging studies have shown that some renal cell carcinomas appear as unicompartmental cysts or multicompartmental cysts, which greatly affect the health and prognosis of patients. 1. Clinical data In our group, there were 10 patients, 6 males and 4 females, aged 35-55 years, with an average age of 46.8 years. The tumor was located on the right side in 3 cases and on the left side in 7 cases, with a diameter of 38-65 mm. 2 cases were found by ultrasound without conscious symptoms, 7 patients had varying degrees of lumbar swelling, 3 cases had microscopic/carnal hematuria, 2 cases had extrarenal manifestations such as malaise and hypothermia. 7 cases had no obvious positive signs on examination, 1 case had a palpable lumbar mass, and 2 cases had percussion pain in the affected kidney. Among the 10 cases, 2 cases showed cystic changes of multiple atria, with uneven septal thickness, uneven echogenicity inside the atria and flaky calcification at the edges, 7 cases showed thickening of the cystic wall and less smooth, and 1 case showed solid cystic changes. 6 of the 10 cases showed single cystic changes on CT. The CT value of the cystic fluid was higher than that of renal cysts, ranging from 17 to 22 Hu. 8 cases had enhancement and 2 cases had no significant enhancement. In the other two cases, the tumors were multi-atrial, separated by a thin cystic wall, with a CT value of 22 Hu. All 10 patients with cystic kidney cancer underwent radical nephrectomy, among which 2 cases were not clearly diagnosed by preoperative imaging and 2 cases were clearly diagnosed by intraoperative frozen biopsy. All patients had clear cell carcinoma on postoperative pathology. The postoperative pathological classification of renal cancer was cystic necrosis in 2 cases, multi-hall cystic renal cancer in 2 cases, single-hall cystic renal cancer in 5 cases, and cystic carcinoma in 1 case. The tumors were treated with immunotherapy or combined with biologic therapy after surgery, with no recurrence at 6 months to 4 years of follow-up. 2. Discussion 2.1 Concept of cystic kidney cancer Hartman et al. classified cystic kidney cancer into cystic necrosis, polycystic kidney cancer, unicystic kidney cancer and simple renal cystic carcinoma from the pathogenesis point of view [2]. granulosa cell carcinoma, now classified as high-grade clear cell carcinoma), papillary renal cell carcinoma, suspicious cell carcinoma, multifocal cystic renal cell carcinoma, Bellini’s collecting duct carcinoma, renal medullary carcinoma, Xp11. 2 translocation/TFE3 gene fusion-associated renal carcinoma, neuroblastoma-associated renal cell carcinoma, mucinous tubular and spindle cell carcinoma. Among them, multifocal cystic renal clear cell carcinoma is classified as a separate type of renal cell carcinoma, characterized by several cystic cavities of variable size and disparity, divided by irregular, thick-walled fibrous septa covered with clear cells. The ratio of male to female patients is 3:1, the age of onset is 20-76 years, and the incidence accounts for 1-2% of all renal tumors [4,5,6], which can be considered as a specific subclinical type of renal cancer due to its characteristic microscopic features and good healing. 2.2 Pathological basis of cystic renal carcinoma In 4% to 15% of renal clear cell carcinomas, cystic degeneration of varying degrees occurs. The causes of cystic transformation include: clear cell carcinomas of proximal tubular epithelial origin that tend to grow as cysts; cystic lumens that may arise from enlarged renal collecting ducts that have been obstructed by the tumor; and cystic transformation that is thought to arise from the fusion of mucin-like material. In addition, tumor necrosis may result in the formation of pseudocysts and simple renal cysts may also undergo malignant transformation. 2.3 Diagnosis of cystic kidney cancer 2.3.1 Clinical presentation Cystic renal carcinoma is a special type of renal cancer, which is rare and can occur in any part of renal parenchyma, but it is more common in the upper and lower parts; it often grows outwardly and is separated from renal tissue by a fibrous pseudo-envelope, with clear and neat borders and uneven thickening of the capsule wall or separation; the contents of the capsule are uneven and may be calcified. The clinical symptoms of cystic kidney cancer are insidious, and the clinical features are the same as those of solid kidney cancer, which can be manifested as soreness and pain in the lumbar region, microscopic/naked eye hematuria, lumbar and abdominal masses, and some patients have extra-renal manifestations such as weakness and hypothermia. 2.3.2 Imaging Ultrasound is of great value in the diagnosis of cystic kidney cancer. In typical cases, the wall of the capsule is thickened and not smooth, and there may be flaky calcification at the edge, and there may be separation within the capsule cavity and uneven internal echogenicity. The clinical features are the same as those of solid renal carcinoma, which may manifest as soreness and pain in the lumbar region, microscopic/meat hematuria, uneven thickness of the interstitial septum, non-echoic areas or dense punctate weakly echogenic areas in the capsule. However, B-ultrasound has some limitations in diagnosing cystic kidney cancer and the diagnosis rate is low, which may be due to the following reasons: tiny protrusions or small nodules in the cystic kidney cancer cyst wall, no echogenicity of fluid in the cyst, uneven echogenicity in the interstitial septum and uneven echogenicity in the interstitial septum. Ultrasonography can detect some small tumors and tumors without blood supply that are difficult to detect by conventional ultrasound, clarify the size, number, nature, location and peripheral conditions of tumors, and observe the blood perfusion of the occupying lesions in the kidney in real time [7]. After contrast injection, the cystic wall and the partitions were enhanced with the number of partitions > 4 and thickness > 1 mm, and the solid nodules were obviously enhanced in the typical lesion. Infected cysts have poor intracapsular sound transmission and lack of contrast perfusion during imaging, with a clear and smooth periphery. Although multifocal cysts may have different echogenic manifestations within the cyst, the cyst wall and intracapsular septa are thin and uniform with good continuity; color Doppler flow imaging rarely detects blood flow signals in the cyst wall and septa, and a small amount of contrast can be seen in the cyst wall or septa after contrast injection, but the number of septa is < 4 and the thickness is < 1 mm. when the cyst bleeds, high echogenicity appears in the liquid dark area, and ultrasonography shows a thin cyst wall and no intracapsular echogenicity. Although the cyst may be filled with different contrast agents. CT is an important tool to diagnose cystic kidney cancer. CT can not only detect kidney lesions, but also determine the nature of the tumor and its relationship with surrounding tissues. The main features of CT scan of cystic kidney cancer are early uneven enhancement, irregular thickening of the cyst wall and septa, wall nodules, calcification, etc., and some of them can be seen as solid masses in the cyst. Most of the tumors have a rough inner wall, and separation or nodules can be seen; a few tumors have a thin and smooth inner wall, which can be easily misdiagnosed. Dynamic enhancement of cystic kidney cancer is highly variable, either with or without significant enhancement, and some tumors are in between. Among them, those with insignificant enhancement are most likely to be misdiagnosed. On the one hand, clear cell carcinoma is easy to be cystic, on the other hand, it is related to the pathological aspect that large cells predominate and the proportion of interstitium is low, so the tumor is easy to be degenerated; in addition, cystic transformation is related to the tissue differentiation of the tumor, most of the significant cystic tumors are differentiated grade I-II, while grade III-IV tumors are common with coagulative necrosis, the cystic cavity formed by necrosis is of unequal size, the inner wall is very irregular and the wall is thick, which is different from the relatively regular and neat cystic transformation. 2.4 Differential diagnosis of cystic kidney cancer Since cystic renal carcinoma is characterized by cystic changes, it needs to be differentiated from the following cystic lesions: (1) common type renal clear cell carcinoma with cystic changes: since the prognosis of the two is significantly different, the differential diagnosis is especially important. (2) Multi-compartmental cystic nephroma: It is a misshapen tumor developed from mesenchymal tissue, and cystic cavities of different sizes can be seen in the cross-section. The nature of cystic fluid is similar to that of multicompartmental cystic renal cell carcinoma, but its covered epithelium is highly columnar or flattened epithelium, and there are fibroblasts, smooth muscle and infantile mesenchymal tissue between cystic cavities. (3) Adult-type polycystic kidney: the lesions are often bilateral, the kidney volume is significantly increased, covered with a single layer of flat or cuboidal epithelium, there is compression of the atrophied renal parenchyma between the cysts, often accompanied by secondary infection. (4) Simple renal cyst: it shows regular wall, clear boundary, and uniform echogenicity of cystic fluid. The nature of the cystic fluid is similar to that of polycystic renal cell carcinoma, but the covered epithelium is highly columnar. The cystic transformation of renal cancer is a hemorrhagic necrotic foci caused by reduced blood supply or hemorrhage in the center of the tumor, the cystic cavity is relatively small, the morphology is irregular, the density is not uniform, and the CT value is higher than water. The invasion of renal cysts by renal cancer can often be seen as part of the tumor and the cyst are fused together, while the non-invaded part of the cyst shows non-cancerous changes and the tumor mainly changes outside the cyst. Intraoperative pathological examination is a more ideal method to confirm the diagnosis, but occasionally we may encounter practical problems that are difficult to confirm the diagnosis. Bosniak classified renal cysts into four categories based on the findings of CT scans. I: Simple renal cyst, its cyst wall is thin, smooth, sharp boundaries, uniform density of cystic fluid (typical density is less than 20HU, higher CT value when benign cyst contains protein or bleeding inside the cyst), and the cyst wall is not enhanced after enhancement scan. Class II: The cyst is mildly complicated, benign lesion, and the cyst wall is not enhanced after enhancement scan, it may be slightly dense or multifocal, in which the separation is thin, and the cyst wall or separation may show a small amount of calcification. Class III: more complex cystic lesions with irregular cystic borders, thick cystic walls with calcification, irregular interatrial septa with thickness greater than 1 mm, or areas of solidity located in the appendages of the cystic wall, signs of solid tissue within the cystic wall or compression of the cystic wall by an external mass. Class IV: the lesion is clearly malignant, the cyst is multihoused, with many separations and connected to the solid part, and an enhancing soft tissue mass can be seen. The cysts of Class II and Class III are sometimes not easily distinguishable and are referred to by Bosniak as IIF, meaning follow-up. Most of the cystic renal carcinomas were classified as Bosniak's class III or IV. After CT-enhanced scan, cystic renal carcinoma appeared as a single- or multi-housed growing cyst with a thick wall and significant enhancement. Unicompartmental cystic renal carcinoma is easy to distinguish from simple cysts, while it is more difficult to distinguish multicompartmental cystic renal carcinoma from multicompartmental cystic nephroma, which is rare and can be surgically explored if it cannot be distinguished. The clinical challenge is to identify Bosniak types II and III. Close observation or renal aspiration biopsy may be an option, but aspiration biopsy carries certain risks and can only obtain limited cells and tissue, so its pathological diagnostic value is somewhat limited. 3. Conclusion The growth pattern of cystic renal carcinoma is quite similar to that of renal cysts, so it is difficult to give a definite diagnosis before surgery. The positive rate of cystic fluid aspiration cytology is less than 1/3, and negative cytology cannot exclude the possibility of malignancy. Familiarity with the imaging features of cystic kidney cancer is the key to improve the diagnostic rate of cystic kidney cancer. Therefore, we believe that for patients with complex renal cysts, preoperative imaging should be perfect and nephrectomy should be prepared. If the cyst wall is found to be less smooth or elevated and there are local thickening changes during surgery, rapid pathological examination must be performed first to exclude cystic kidney cancer and avoid unnecessary nephrectomy. Reference. [McGuire, Barry B; Fitzpatrick, John M Current Opinion in Urology. 20(5):349-354, September 2010. [2] Hartman DS ,Davis CJ ,Johns T ,et al . Cystic renal cell carcinoma[J ] . Urology ,1986 ,28 (2) :145-153. [3] Ma JF, Guan YY, Zheng S et al. New advances in the pathologic classification of renal cell carcinoma[ J] . Journal of Oncology, 2008, 14: 334-336. [LopezBelt ran A ,Scarpelli M ,Montironi R ,et al . 2004 WHO classification of t he renal tumors of t he adult s [J ] . Eur Urol , 2006 ,49 (5) :798-805. [5] Murphy WM, Grignon DJ, Perlman EJ. Kidney tumors in adults. in: Tumors of the Kidney, Bladder, and Related Urinary Structures. Washington, DC: American Registry of Pathology; 2004:121C123. [6] Shah V, Pathak H. Multilocular cystic renal cell carcinoma: a report of two cases with a rare feature.Internet J Urol. 2010:6(2). [7] Fan Z, An LCH. Ultrasonography diagnosis of giant renal cell carcinoma in a case. Chinese Medical Imaging Technology, 2010, 26( 2): 395