[Using laser radiation in partial nephrectomy for renal tumors]

In recent years, the number of organ-sparing operations for renal tumors has been increasing steadily due to comparable oncological outcomes and the desire to preserve functioning renal parenchyma. Another technique, which is becoming increasingly popular, is so-called zero ischemia partial nephrectomy, which allows bleeding to be controlled during the operation without clamping the renal artery, thus avoiding renal ischemic injury. One of the most interesting and promising instruments for partial nephrectomy is a laser radiation. It combines good cutting and coagulating properties, thus enabling partial nephrectomy to be carried out without vascular clamping. This literature review presents the physical basis of laser technology and evidence from published clinical studies on using of various types of laser radiation for partial nephrectomy. The prospects for further development of the technique are discussed.

Improved laparoscopic nephron-sparing surgery for renal cell carcinoma based on the precise anatomy of the nephron

The aim of the present study was to investigate a method of laparoscopic nephron-sparing surgery (LNSS) for renal cell carcinoma (RCC) based on the precise anatomy of the nephron, and to decrease the incidence of hemorrhage and urinary leakage. Between January 2012 and December 2013, 31 patients who presented to the General Hospital of the People's Liberation Army (Beijing, China) were treated for RCC. The mean tumor size was 3.4±0.7 cm in diameter (range, 1.2-6.0 cm). During surgery, the renal artery was blocked, and subsequently, an incision in the renal capsule and renal cortex was performed, at 3-5 mm from the tumor edge. Subsequent to the incision of the renal parenchyma, scissors with blunt and sharp edge were used to separate the base of the tumor from the normal renal medulla, in the direction of the ray medullary in the renal pyramids. The basal blood vessels were incised following the hemostasis of the region using bipolar coagulation. The minor renal calyces were stripped carefully and the wound was closed with an absorbable sutures. The arterial occlusion time, duration of surgery, intraoperative bleeding volume, post-operative drainage volume, pathological results and complications were recorded. The surgery was successful for all patients. The estimated average intraoperative bleeding volume was 55.7 ml, the average surgical duration was 95.5 min, the average arterial occlusion time was 21.2 min, the average post-operative drainage volume was 92.3 ml and the average post-operative length of hospital stay was 6.1 days. No hemorrhage or urinary leakage was observed in the patients following the surgery. LNSS for RCC based on the precise anatomy of the nephron was concluded to be effective and feasible. The surgery is useful for the complete removal of tumors and guarantees a negative margin, which may also decrease the incidence of hemorrhage and urinary leakage following surgery.

Anesthesia for bench surgery

Surgical removal of the kidney tumor outside the body, (ex vivo renal bench surgery) followed by auto transplantation is an emerging and often done procedure to reconstruct the urinary tract. It possesses immense challenges to both the anesthesiologists and the surgeons. The risks are multiplied if you are performing the surgery on a solitary functioning kidney. Here, we are describing the anesthetic management of 70-year-old male post nephrectomy patient undergoing renal auto transplantation by bench surgery. Our primary goals for perioperative management were to maintain a stable hemodynamics throughout the procedure, to reduce fluid overload during the period of extracorporeal surgery, to maintain perfusion for the transplanted solitary kidney, to control bleeding to a minimum, and to provide adequate analgesia for the patient. We made use of a balanced anesthetic technique and stringent monitoring standards to bring forth a successful outcome for the patient. At the end of his hospital stay, patient went home with a healthy, normally functioning kidney.

Preoperative evaluation of renal artery in patients with renal tumor: Using noncontrast-enhanced magnetic resonance angiography

To investigate the feasibility of the noncontrast-enhanced magnetic resonance angiography (NCE-MRA) to evaluate renal arteries before partial nephrectomy (PN).Retrospective analyzed 479 patients who underwent renal surgery between January 2013 and December 2015 with NCE-MRA or computed tomographic angiography (CTA) renal artery image reconstruction preoperative in our department. The renal artery reconstruction score (RARS) was based on the level of artery visualization in a 4-class criterion, and the R.E.N.A.L nephrometry score (R.E.N.A.L), arterial based complexity (ABC) were also analyzed.Of the 479 patients, the overall-lever RARS was 3.62, and the average in 2 groups was no significant difference (NCE-MRA vs CTA, P = 0.072). The performance of NCE-MRA in PN group was similar with CTA. Further comparison demonstrated that the efficiency of NCE-MRA in moderate- or low-degree tumor according to the R.E.N.A.L and ABC complexity less than 3S was equal to CTA. However, high degree (P < 0.001), 3S (P = 0.027), or 3H (P < 0.001) would affect the imaging of renal artery. Intragroup analysis showed that tumor complexity such as max tumor size (r = -o.351, P < 0.001), R.E.N.A.L (r = -0.439, P < 0.001), and ABC (r = -0.619, P < 0.001) were closely correlated with the NCE-MRA performance. The images of 2 sides of the kidney were compared in single person as well, which was meaningful for NCE-MRA patients only (NCE-MRA, P < 0.001; CTA, P = 0.182).The renal artery reconstruction performed by NCE-MRA is feasible and has a similar achievement in the PN potential recipients, with a lower side effect, and meets the requirements for making surgical decision. It has a broad application prospect in clinical practice; however, it still needs to further improve the ability in more complex tumors.

Surgical treatment of kidney tumors - contemporary trends in clinical practice

INTRODUCTION

The aim of this article is to generally describe the roles of main surgical modalities in treatment of renal tumors, especially in the CT1a category in clinical practice. Surgical modalities include the following: laparoscopic or open resection (LR, OR) and laparoscopic or open nephrectomy (LN, ON). Representation of these methods has been changing over years due to improved operative skills and equipment and due to a shift of tumors to the lower T categories.

MATERIAL AND METHODS

The sources of data were surgeries performed for renal tumors at the institution of the main author during the period 2002 to III/2016, reaching a total of 2204 cases (546 ONs, 647 LNs, 668 ORs and 343 LRs). Patients indicated for percutaneous ablative therapy or active surveillance were not included.

RESULTS

During the whole period, the proportions of methods were: ONs 24.8%, LNs 29.4%, ORs 30.3%, LRs 15.6%. But during the years 2014 - III/2016, these changed to 12.6%:26.3%:31.6%:29.4% (in cT1a 1.7%:8.3%:37.8%:52.2%). Category cT1a constitutes in the years 2007 - III/2016 41.3%, in 2014 - III/2016 50.9%.

CONCLUSIONS

Resections and minimally invasive approaches are being performed more frequently and are the preferred methods in surgical treatment of kidney tumors. Resection is now indicated in about 60% of cases (open vs. laparoscopic resection are used nearly equally with a slight tendency for laparascopic predomination). In the cT1a category (amounting to approximately 50% of all surgically treated tumors), resection is possible in about 85-90% of cases.

Primary renal lymphoma: A case report and literature review

Primary renal lymphoma (PRL) is a rare disease, with no more than 70 cases reported in the literature. The present study reports the case of a 70-year-old woman with PRL. The patient was asymptomatic, however, a mass on the right kidney was identified incidentally during routine physical examination. Computed tomography revealed a mass in the right kidney that was 3.6 cm in diameter. Subsequently, right nephrectomy was performed. The histological evaluation of the nephrectomy specimen showed diffuse large B-cell non-Hodgkin's lymphoma. The patient was treated with 6-8 cycles of a cyclophosphamide, epirubicin, vindesine and dexamethasone regimen. Follow-up examination performed after 2 months of treatment revealed no evidence of local recurrence. The present study also reviewed 49 cases of PRL that have been reported since 1989. It was found that a shorter survival time was experienced by patients with bilateral PRL (mean, 21 months) compared with unilateral PRL (mean, 68 months). A shorter survival time was also experienced by patients who were treated with chemotherapy only (mean, 15.8 months) compared with those who were treated with combination chemotherapy and surgery (mean, 49.4 months).

Ewing sarcoma/primitive neuroectodermal tumor of the kidney treated with chemotherapy including ifosfamide

Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET) of the kidney is extremely rare, and is usually diagnosed after nephrectomy without neoadjuvant chemotherapy. Although ifosfamide and etoposide improve survival to a great extent in ES/PNET, the use of nephrotoxic agent, particularly ifosfamide, is a concern after nephrectomy. We describe the case of a 14-year-old female patient with abdominal mass who was diagnosed with ES/PNET of the right kidney after nephrectomy. Adjuvant chemotherapy including ifosfamide and etoposide were given. The estimated glomerular filtration rate decreased to 75% after the end of therapy. There was no evidence of recurrence 70 months after initial diagnosis.

Predictive factors for complete renal tumor ablation using RFA

BACKGROUND

Radiofrequency ablation (RFA) can be used to treat renal masses in patients where surgery is preferably avoided. As tumor size and location can affect ablation results, procedural planning needs to identify these factors to limit treatment to a single session and increase ablation success.

PURPOSE

To identify factors that may affect the primary efficacy of complete renal tumor ablation with radiofrequency after a single session.

MATERIAL AND METHODS

Percutaneous RFA (using an impedance based system) was performed using computed tomography (CT) guidance. Fifty-two renal tumors (in 44 patients) were retrospectively studied (median follow-up, 7 months). Data collection included patient demographics, tumor data (modified Renal Nephrometry Score, histopathological diagnosis), RFA treatment data (electrode placement), and follow-up results (tumor relapse). Data were analyzed through generalized estimating equations.

RESULTS

Primary efficacy rate was 83%. Predictors for complete ablation were optimal electrode placement (P = 0.002, OR = 16.67) and increasing distance to the collecting system (P = 0.02, OR = 1.18). Tumor size was not a predictor for complete ablation (median size, 24 mm; P = 0.069, OR = 0.47), but all tumors ≤2 cm were completely ablated. All papillary tumors and oncocytomas were completely ablated in a single session; the most common incompletely ablated tumor type was clear cell carcinoma (6 of 9).

CONCLUSION

Optimal electrode placement and a long distance from the collecting system are associated with an increased primary efficacy of renal tumor RFA. These variables need to be considered to increase primary ablation success. Further studies are needed to evaluate the effect of RFA on histopathologically different renal tumors.

Simultaneous metastases of clear cell renal cell carcinoma to the urinary bladder and left retroperitoneal space: A case report and review of the literature

The present study describes an extremely rare case of simultaneous metastases of clear cell renal cell carcinoma (ccRCC) to the urinary bladder and left retroperitoneal space, occurring subsequent to an open radical nephrectomy. A review of the literature is also considered. A 70-year-old man presenting with diabetes mellitus and hypertension was referred to West China Hospital (Chengdu, China) with constant left flank pain that had been apparent for 2 months. Ultrasonography identified a heterogeneous tumor with a solid component measuring 4.4×3.4×5.0 cm, and computed tomography (CT) revealed a circumscribed and contrast-enhanced tumor in the left kidney. Subsequent pathological analysis of the specimen, obtained from an open radical nephrectomy, confirmed the presence of ccRCC. At 1 month after the radical nephrectomy, an abdominopelvic CT scan identified tumors located on the posterior bladder wall and also in the left retroperitoneal space, forming due to hematuria and acute urinary clot retention. There was no evidence of metastasis to the lungs, bones or other organs. A transurethral resection of the bladder tumor was performed and pathological analysis of the bladder specimen demonstrated metastatic ccRCC. Extensive hydrothorax and general anasarca presented half a month after the transurethral resection, with the patient subsequently succumbing 15 days later.

Usefulness of selective renal artery embolization for urinary fistula following partial nephrectomy: Two case reports

The present study reported two cases in which selective artery embolization were identified to assist in resolving urinary fistulae following partial nephrectomies. The first case involved a 51-year-old male who received a mini-incision partial nephrectomy with renorrhaphy. Following the operation, urine continued to discharge from the retroperitoneal drain. Selective renal artery embolization of the upper calyx at post-operation day 20 was highly effective and urine output from the drain stopped immediately. Case 2 involved a 66-year-old male, who also suffered from a urinary fistula following a partial nephrectomy. Selective renal artery embolization performed at post-operation day 21 was again effective. In each case, the upper calyx was separated from the renal pelvis. These cases demonstrated that suturing of the collecting system and renal parenchyma may result in the separation of the urine pathway, and that selective renal artery embolization appears to be a highly effective treatment in such cases.

Uncommon renal tumors in children: A single center experience

Aims:

Scrutiny over the clinical behaviors, management, and the final outcome of some rare renal neoplasm in order to find out some hidden facts about these tumors which are playing an important role in the disease course and its management.

Materials and Methods:

Retrospective evaluation of uncommon (non-Wilms’) renal neoplasm in the pediatric population in a tertiary care center. Fifteen cases of uncommon renal tumors were treated in our institution over the last 5 years (January 2008 to December 2012). The cases were tabulated in the form of age, sex, mode of presentation, preoperative investigations, intraoperative grading, pathological type, postoperative management and the final outcome. The patients were followed up for 2 years (clinically every 3 months and ultrasonography abdomen in every 6 months for first 2 years) in order to see any evidence of recurrence and complications related to postoperative chemotherapy.

Results:

Out of 15 cases, four cases were clear cell sarcoma (CCS) (26.6%), three cases were rhabdoid tumor (20%), three cases were congenital mesoblastic nephroma (20%), two cases were multilocular cystic nephroma (13.3%), two cases were renal teratoma (13.3%), and one case of teratoid Wilms’ tumor (6.6%). There were two deaths (one CCS and one rhabdoid tumor) due to chemotherapy-related toxicity but no recurrence. Three patients were lost during postoperative follow-up; ten patients are doing well and getting a regular visit in the follow-up clinic.

Conclusion:

The clinical presentations of these uncommon renal tumors are similar to that of Wilms’ tumor. Thus, preoperative diagnosis is difficult even with modern imaging techniques. Some of these tumors (CCS, rhabdoid tumor) are rapidly progressing and have a poor outcome. Hence, early intervention in the form of complete surgical resection of the tumor (whenever possible) and postoperative chemo/radiotherapy are imperative for fruitful outcome.

Molecular genetics and immunohistochemistry characterization of uncommon and recently described renal cell carcinomas

Renal cell carcinoma (RCC) compromises multiple types and has been emerging dramatically over the recent several decades. Advances and consensus have been achieved targeting common RCCs, such as clear cell carcinoma, papillary RCC and chromophobe RCC. Nevertheless, little is known on the characteristics of several newly-identified RCCs, including clear cell (tubulo) papillary RCC, Xp11 translocation RCC, t(6;11) RCC, succinate dehydrogenase (SDH)-deficient RCC, acquired cystic disease-associated RCC, hereditary leiomyomatosis RCC syndrome-associated RCC, ALK translocation RCC, thyroid-like follicular RCC, tubulocystic RCC and hybrid oncocytic/chromophobe tumors (HOCT). In current review, we will collect available literature of these newly-described RCCs, analyze their clinical pathologic characteristics, discuss their morphologic and immunohistologic features, and finally summarize their molecular and genetic evidences. We expect this review would be beneficial for the understanding of RCCs, and eventually promote clinical management strategies.

The Value of Mitotic Count and Ki67 Proliferation Index in Congenital Mesoblastic Nephroma

OBJECTIVE

We aimed to define the histopathologic features and proliferative rate of congenital mesoblastic nephroma (CMN) as a risk factor for recurrence.

METHODS

Fourteen cases of CMN among 138 registered pediatric renal tumors were retrospectively reviewed. The prognostic impact for mitotic rate and Ki67 index was investigated.

RESULTS

There were four (28.6%) classic, six (42.9%) cellular, and four (28.6%) mixed type CMNs, with average Ki-67 counts of 16.75% in the classic CMN, and 53.2% in the tumors with cellular components (both mixed and cellular CMNs). Twelve patients (85.7%) were aged less than six months. Tumors with cellular component showed significantly larger tumor diameter and higher Ki-67 index (p = 0.015 and p = 0.016, respectively). The patient with cellular CMN, whose tumor showed the highest mitotic rate (4.9/HPF), but not the highest Ki67 index (57.4%), died of recurrent disease with distant metastasis.

CONCLUSION

Proliferative markers-mitotic count and Ki67 index-have limited value to predict recurrence or metastasis in CMNs with a cellular component.

Malignant lymphoma occurring simultaneously in the urinary bladder wall and bilateral renal parenchyma: A case report

A 67-year-old man was admitted to hospital with acid regurgitation, acute right lower abdominal pain and mild fever. Multiple suspicious mass lesions were detected in the patient's kidneys, the right side wall of his bladder and the right lower ureter, using CT urography and PET-CT. He underwent palliative surgery of the bladder and percutaneous renal biopsy. Postoperative histopathological examination and immunohistochemical staining indicated that the tumor was consistent with diffuse large B-cell lymphoma (DLBCL). Although DLBCL is by far the most common type of non-Hodgkin's lymphoma, it is rare for DLBCL to simultaneously involve the kidneys, bladder and the lower ureteric tract.

Lithium and renal and upper urinary tract tumors - results from a nationwide population-based study

OBJECTIVES

A recent alarming finding suggested an increased risk of renal tumors among long-term lithium users. The objectives of the present study were to estimate rates of renal and upper urinary tract tumors (RUT), malignant and benign, among individuals exposed to successive prescriptions for lithium, anticonvulsants, and other psychotropic agents used for bipolar disorder, and among unexposed individuals.

METHODS

This was a nationwide, population-based longitudinal study including time-specific data from all individuals exposed to lithium (n = 24,272) or anticonvulsants (n = 386,255), all individuals with a diagnosis of bipolar disorder (n = 9,651), and a randomly selected sample of 1,500,000 from the Danish population. The study period was from 1995 to 2012, inclusive. Outcomes were hazard rate ratios (HR) for RUT in three groups: (i) combined malignant and benign, (ii) malignant, and (iii) benign. Analyses were adjusted for the number of prescriptions for lithium/anticonvulsants, antipsychotic agents, antidepressants, and use of all other types of medication; age; gender; employment status; calendar year; and a diagnosis of bipolar disorder.

RESULTS

Continued treatment with lithium was not associated with increased rates of RUT [adjusted HR malignant or benign: 0.67-1.18, p (trend) = 0.70; adjusted HR malignant: 0.61-1.34, p (trend) = 0.90; adjusted HR benign: 0.74-1.18, p (trend) = 0.70]. Similarly, continued treatment with anticonvulsants was not associated with increased rates of RUT [adjusted HR malignant or benign: 0.97-1.18, p (trend) = 0.10; adjusted HR malignant: 0.82-1.15, p (trend) = 0.80; adjusted HR benign: 0.94-1.36, p (trend) = 0.20]. The associations were confirmed among the 9,651 patients with a diagnosis of bipolar disorder.

CONCLUSIONS

Treatment with lithium is not associated with increased rates of RUT.

Reconstructive kidney surgery for organ-preserving therapy of renal tumors

Background: The objective of this study was to evaluate differences in various clinical endpoints in patients with reconstructive surgery by renal partial nephrectomy for tumors up to 4 cm compared to tumors larger than 4 cm.

Material and methods: A total of 170 partial renal resection patients that presented malignant tumors were included in the retrospective study. Data was analyzed retrospectively based on internal clinic files, as well as a questionnaire to enhance the follow-up clinical outcomes data obtained. The most important outcomes determined included post-operative renal function, intra- and post-operative complications, local recurrence rate and total survival time.

Results: The local recurrence rate was 6.1% for tumors up to 4 cm in size, compared to 14.9% for tumors that were larger than 4 cm. Compared to results for partial resection of T1a tumors, results for partial resection of tumors larger than 4 cm are worse in terms of post-operative renal function (p=0.007), as well as in terms of a total complications rate (p=0.048). It is important to note that there was not only a higher risk of post-operative bleeding that required transfusions (p=0.012), but also a higher risk of a hypertensive episode during the post-operative period reviewed (p=0.022). In addition, the total survival time for patients presenting tumors of up to 4 cm in size was significantly better (p=0.003).

Conclusion: The results of our retrospective study of 170 patients that underwent partial renal resection after the diagnosis of malignant tumors, is that partial renal resection presents an oncologicaly safe surgical solution with low local recurrence rates. Additionally, partial resection in case of tumors that are larger than 4 cm showed worse post-operative renal function, a higher complications rate and a worse survival rate.

Castleman's disease of the kidney: Sonographic findings

We report a case of rare Castleman's disease of the kidney that mimicked a renal neoplasm with emphasis on the imaging and histologic findings. A 47-year-old man presented with dyspeptic symptoms. Ultrasound revealed a vascular, heterogeneous mass in the left kidney. Multiphasic CT scan confirmed an enhancing lesion with enlarged left para-aortic lymph nodes suspicious for nodal metastases. The provisional diagnosis was renal cell carcinoma. Percutaneous biopsy yielded a diagnosis of Castleman's disease of the hyaline-vascular type. Despite advancement in imaging modalities, differentiation of hyaline-vascular variant of Castleman's disease from hypervascular renal neoplasm remains difficult and the final diagnosis requires histopathological confirmation.

AB118. Feasibility and safety evaluation of pure laparoscopic radical nephrectomy and thrombectomy for renal tumor patients with venous tumor thrombus

Objective

Methods

Results

Conclusions

Total nephrectomy with nephron-sparing surgery for a giant bilateral renal angiomyolipoma: A case report

The current report presents the case of a 50-year-old female who presented with a giant bilateral renal angiomyolipoma (AML). After assessing the patient's symptoms, the tumor size and renal function, the patient underwent a total nephrectomy for the right AML, which measured 28×20×14 cm and nephron-sparing surgery was performed without preoperative selective angiographic embolization for a further 3 AMLs in the left kidney, the largest of which had a diameter of 12 cm. The introperative bleeding volume was at an acceptable level and the renal function was stable. No local recurrence was observed and no dialysis was required during follow-up. The strategy of the treatment in this report should be considered when treating similar tumors.

Undiagnosed giant cystic pheochromocytoma: A case report

Giant cystic pheochromocytomas (GPCCs) are rare adrenal tumors and the majority of them present as asymptomatic. As a result GPCCs often remain undiagnosed until surgery and therefore the surgical team face a greater challenge in perioperative management. The present study describes the case of a 36 year-old woman with an undiagnosed GPCC, which was successfully resected despite the occurrence of perioperative cardiovascular events, including hypertension, hypotension, ventricular arrhythmias, acute heart failure, acute myocardial infarction, and the patient was discharged home without any recurrence. It should be considered in retroperitoneal tumour of patients with nonspecific symptoms and given adequate treatment to promote the perioperative safety.

An Unusual Presentation of Cystic Nephroma in an Adult Man

Cystic nephroma (CN) is an uncommon, benign lesion of the kidney, whose clinical presentation is nonspecific with symptoms such as flack pain, hematuria and urinary tract infection. There are two peaks in the incidence of the tumor, with a bimodal distribution presenting in children between three months and two years, and in adults over 30-years of age. We report a case of CN in the middle part of the left kidney in a 66-year-old male that presented with a singular unilocular, well-circumscribed cyst containing numerous calcifications on the walls and with unremarkable thin or relatively thicker septa from the border with the renal parenchyma, but no solid components. Laparoscopic nephrectomy was performed. Images, histopathological and immunohistochemical features, that are potentially useful for refining this lesion, are discussed.

Primary carcinoid tumor of the kidney with estrogen and progesterone receptor expression

Primary carcinoid tumors are uncommon neoplasms in the kidney. The current study presents a case of primary carcinoid tumor of the kidney in a 49-year-old female who suffered from painless gross hematuria for half a month. Left hydronephrosis, a horseshoe kidney and a space-occupying lesion of the left ureter were found by abdominal computed tomography scans and ultrasonic testing. Surgery was performed and an oval tumor was found under the left ureter; the tumor and left kidney were excised completely. The neoplasm was composed of solid nests of cells, trabeculae, adenoid structures and anastomosing cords in a loose and myxoid background. The tumor cells, which were consistent in volume, exhibited centrally oval nuclei with inconspicuous nucleoli, and eosinophilic finely granular cytoplasm. Upon immunohistochemical staining, the neoplastic cells were positive for AE1/AE3, vimentin, synaptophysin, chromogranin A, estrogen receptor and progesterone receptor, while being negative for epithelial membrane antigen, inhibin A, cluster of differentiation (CD)99, S-100 and CD10. Based on the histological characteristics, a diagnosis of primary carcinoid tumor of the left kidney was formed. The patient did not receive further treatment. The total follow-up period was 18 months after the surgery and repeated imaging examinations every 6 months revealed no recurrence.

Distinctive expression patterns of glycoprotein non-metastatic B and folliculin in renal tumors in patients with Birt-Hogg-Dubé syndrome

Birt–Hogg–Dubé syndrome (BHD) is an inherited disorder associated with a germline mutation of the folliculin gene (FLCN). The affected families have a high risk for developing multiple renal cell carcinomas (RCC). Diagnostic markers that distinguish between FLCN-related RCC and sporadic RCC have not been investigated, and many patients with undiagnosed BHD fail to receive proper medical care. We investigated the histopathology of 27 RCCs obtained from 18 BHD patients who were diagnosed by genetic testing. Possible somatic mutations of RCC lesions were investigated by DNA sequencing. Western blotting and immunohistochemical staining were used to compare the expression levels of FLCN and glycoprotein non-metastatic B (GPNMB) between FLCN-related RCCs and sporadic renal tumors (n = 62). The expression of GPNMB was also evaluated by quantitative RT-PCR. Histopathological analysis revealed that the most frequent histological type was chromophobe RCC (n = 12), followed by hybrid oncocytic/chromophobe tumor (n = 6). Somatic mutation analysis revealed small intragenic mutations in six cases and loss of heterozygosity in two cases. Western blot and immunostaining analyses revealed that FLCN-related RCCs showed overexpression of GPNMB and underexpression of FLCN, whereas sporadic tumors showed inverted patterns. GPNMB mRNA in FLCN-related RCCs was 23-fold more abundant than in sporadic tumors. The distinctive expression patterns of GPNMB and FLCN might identify patients with RCCs who need further work-up for BHD.

Retroperitoneal schwannomas of renal and pararenal origin: presentation of two case reports

Retroperitoneal schwannomas are a rare entity. They originate from the Schwann cells of the nerve sheaths and may be of renal or pararenal origin. We report on two patients with retroperitoneal schwannomas, who received surgery under the suspicion of renal cell carcinoma.

Immunohistochemical characterization of renal tumors in patients with Birt-Hogg-Dubé syndrome

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant disorder associated with a germline mutation of folliculin (FLCN). The affected families are at a high risk for developing multiple renal cell carcinomas (RCC). Little is known about the immunostaining patterns of mutant FLCN-associated RCCs. We investigated 32 RCCs obtained from 17 BHD patients. The studied tumors included chromophobe RCCs (n = 15), hybrid oncocytic/chromophobe tumors (HOCT) (n = 14) and clear cell RCCs (n = 3). Almost all chromophobe RCCs and HOCTs revealed positive staining for S100A1, Ksp-cadherin and CD82. They stained either focally or diffusely for CK7, and were negative for CA-IX. All clear cell RCCs were positively stained for CA-IX and negative for CK7. These data confirmed that mutant FLCN-associated oncocytic and clear cell RCCs exhibited generally similar immunostaining patterns compared to their sporadic counterparts. Frequent positive staining for S100A1, Ksp-cadherin and CD82 in chromophobe RCCs and HOCTs indicated that these two types were relatively similar rather than distinctively different in their patterns of immunoreactivity. Characteristic peri-nuclear halos and polygonal cells with clear cytoplasm, which often misleads pathologists into the diagnosis of clear cell RCC, should be carefully examined using an immunohistochemical panel including CA-IX, Ksp-cadherin, CD82 and CK7.