Showing papers on "Papillary renal cell carcinomas published in 2015"

Recurrent chromosomal gains and heterogeneous driver mutations characterise papillary renal cancer evolution

Abstract: Papillary renal cell carcinoma (pRCC) is an important subtype of kidney cancer with a problematic pathological classification and highly variable clinical behaviour. Here we sequence the genomes or exomes of 31 pRCCs, and in four tumours, multi-region sequencing is undertaken. We identify BAP1, SETD2, ARID2 and Nrf2 pathway genes (KEAP1, NHE2L2 and CUL3) as probable drivers, together with at least eight other possible drivers. However, only ~10% of tumours harbour detectable pathogenic changes in any one driver gene, and where present, the mutations are often predicted to be present within cancer sub-clones. We specifically detect parallel evolution of multiple SETD2 mutations within different sub-regions of the same tumour. By contrast, large copy number gains of chromosomes 7, 12, 16 and 17 are usually early, monoclonal changes in pRCC evolution. The predominance of large copy number variants as the major drivers for pRCC highlights an unusual mode of tumorigenesis that may challenge precision medicine approaches.

Papillary renal cell carcinoma: A review of the current therapeutic landscape

Abstract: Renal cell carcinoma (RCC) is the most common cancer of the kidney and accounts for 2-3% of all adult malignancies. Clear cell carcinoma represents the most common histologic subtype, while papillary Renal Cell Carcinoma (pRCC) accounts for 10-20% of all renal cell cancers. While the inactivation of VHL gene can be found in the majority of clear cell carcinomas, different molecular mechanisms are involved into pRCC biology. Mutations in the MET oncogene are an essential step into the pathogenesis of hereditary pRCC forms, but they can be found only in a small rate of sporadic cases. Several agents, including anti-VEGF drugs and mTOR inhibitors, are possible options in the treatment of advanced and metastatic pRCC, following the demonstration of efficacy obtained in clinical trials including all RCC histologic subtypes. However, data specifically obtained in the subgroup of patients affected by pRCC are limited and not conclusive. Several ongoing trials are evaluating the efficacy of targeted therapy in papillary form. However, more rationale approaches based on molecular studies would help improving the outcome of these patients. Among others, MET inhibitors and targeted immunotherapy are promising new strategies for hereditary and sporadic disease. This review summarizes current knowledge on pRCC tumorigenesis and discusses recent and ongoing clinical trials with new therapeutic agents.

New Strategies in Renal Cell Carcinoma: Targeting the Genetic and Metabolic Basis of Disease

Abstract: The development of new forms of treatment of advanced renal cell carcinoma over the past two decades has been primarily focused on targeting the VHL/HIF pathway. The recent identification of mutations of chromatin-remodeling genes in clear-cell renal carcinoma (ccRCC), of genomic heterogeneity, and of a Warburg-like metabolic phenotype in advanced disease has had a profound effect on our understanding of the evolution of ccRCC and on potential approaches to personalized therapy. Early approaches to therapy for patients with advanced type I papillary RCC that have centered around the MET/HGF pathway will expand as more genomic information becomes available. Sporadic and familial type II papillary renal cell carcinoma are characterized by enhanced aerobic glycolysis and share an antioxidant response phenotype. In fumarate hydratase-deficient RCC, fumarate-induced succination of KEAP1 activates Nrf2 signaling. CUL3 and Nrf2 mutations as well as an Nrf2 activation phenotype are found in sporadic type II papillary RCC. Therapeutic approaches designed to target the Nrf2 pathway as well as to impair blood flow and glucose delivery in these cancers that are highly dependent on a robust tumor vasculature and on ready availability of glucose for energy production and glycolysis are in development.

Evaluation of Urine Aquaporin-1 and Perilipin-2 Concentrations as Biomarkers to Screen for Renal Cell Carcinoma: A Prospective Cohort Study

Abstract: Importance Historically, early detection of small asymptomatic kidney tumors presages better patient outcome. Screening for asymptomatic renal tumors by abdominal imaging is not cost-effective and cannot reliably distinguish benign from malignant tumors. Objective This investigation evaluated the clinical utility, sensitivity, and specificity of urine aquaporin-1 (AQP1) and perilipin-2 (PLIN2) concentrations as unique, noninvasive biomarkers to diagnose malignant clear cell or papillary renal cell carcinoma (RCC) in a screening paradigm. Design, Setting, and Participants From February through December 2012, urine samples were obtained from 720 patients undergoing routine abdominal computed tomography (CT) (screening population), 80 healthy controls, and 19 patients with pathologically confirmed RCC. Main Outcomes and Measures Urine AQP1 and PLIN2 concentrations were measured by sensitive and specific enzyme-linked immunosorbent assay and Western blot procedures, respectively, in all groups. In the otherwise asymptomatic screening population, the absence or presence of a renal mass and RCC were verified by abdominal CT and by postnephrectomy pathologic diagnosis, respectively. Results Urine AQP1 and PLIN2 concentrations were significantly higher (all P Conclusions and Relevance These results demonstrate the clinical utility, specificity, and sensitivity of urine AQP1 and PLIN2 to diagnose RCC. These tumor-specific proteins have high clinical validity and substantial potential as specific diagnostic and screening biomarkers for clear cell or papillary RCC and in the differential diagnosis of imaged renal masses.

Correcting the Shrinkage Effects of Formalin Fixation and Tissue Processing for Renal Tumors: toward Standardization of Pathological Reporting of Tumor Size.

Abstract: Given the importance of correctly staging renal cell carcinomas, specific guidelines should be in place for tumor size measurement. While a standard means of renal tumor measurement has not been established, intuitively, tumor size should be based on fresh measurements. We sought to assess the accuracy of postfixation and microscopic measurements of renal tumor size, as compared to fresh measurements and radiographic size. Thirty-four nephrectomy cases performed by a single surgeon were prospectively measured at different time points. The study cases included 23 clear cell renal cell carcinomas, 6 papillary renal cell carcinomas, and 5 other renal tumors. Radiologic tumors were 12.1% larger in diameter than fresh tumors (P<0.01). Furthermore, fresh specimens were 4.6% larger than formalin-fixed specimens (P<0.01), and postfixation measurements were 7.1% greater than microscopic measurements (P<0.01). The overall mean percentage of shrinkage between fresh and histological specimens was 11.4% (P<0.01). Histological processing would cause a tumor stage shift from pT1b to pT1a for two tumors in this study. The shrinkage effects of formalin fixation and histological processing may result in understaging of renal cell carcinomas. The shrinkage factor should be considered when reporting tumor size.

Urine Aquaporin 1 and Perilipin 2 Differentiate Renal Carcinomas From Other Imaged Renal Masses and Bladder and Prostate Cancer

Abstract: Objective To evaluate the sensitivity and specificity of urine aquaporin 1 (AQP1) and perilipin 2 (PLIN2) concentrations to diagnose clear cell or papillary renal cell carcinoma (RCC) by comparing urine concentrations of these unique biomarkers in patients with RCC, noncancer renal masses, bladder cancer, and prostate cancer. Methods From February 1, 2012, through October 31, 2012, preoperative urine samples were obtained from patients with a presumptive diagnosis of RCC based on an imaged renal mass, prostate cancer, or transitional cell bladder cancer. Imaged renal masses were diagnosed postnephrectomy—as malignant or benign—by histology. Urine AQP1 and PLIN2 concentrations were measured by using a sensitive and specific Western blot and normalized to urine creatinine concentration. Results Median concentrations of urine AQP1 and PLIN2 in patients with clear cell and papillary RCC (n=47) were 29 and 36 relative absorbance units/mg urine creatinine, respectively. In contrast, median concentrations in patients with bladder cancer (n=22) and prostate cancer (n=27), patients with chromophobe tumors (n=7), and patients with benign renal oncocytomas (n=9) and angiomyolipomas (n=7) were all less than 10 relative absorbance units/mg urine creatinine (Kruskal-Wallis test, P Conclusion These results support the specificity and sensitivity of urine AQP1 and PLIN2 concentrations for RCC. These novel tumor-specific proteins have high clinical validity and high potential as specific screening biomarkers for clear cell and papillary RCC as well as in the differential diagnosis of imaged renal masses. Trial Registration clinicaltrials.gov Identifier: NCT00851994

Do Clear Cell Papillary Renal Cell Carcinomas Have Malignant Potential

Abstract: There have been no recurrences or metastases of clear cell papillary renal cell carcinoma (CCPRCC) in 268 reported cases with follow-up in the English-language literature. We identified all our cases of CCPRCC (1990 to 2013), reviewing all cases that preceded the formal designation of the entity. Immunohistochemical stains were performed on 32 cases during their initial workup. In addition, stains for carbonic anhydrase IX and cytokeratin 7 were performed on 2 cases, one with atypical follow-up and the other with a more compact morphology, although not performed initially. An extended panel with AMACR, CD10, and renal cell carcinoma (RCC) was added to the case with atypical follow-up. Fluorescence in situ hybridization for chromosomes 3p, 7, and 17 was performed on the latter case and on another clinically presumed metastatic tumor. In classic cases, immunohistochemical staining was not performed. Fifty-eight patients (31 women; 27 men) with follow-up data were included in our study; 39 cases were from our consult service. The patients' ages ranged from 36 to 83 years. Thirty-five patients had cystic or partially cystic lesions; 6 tumors were multifocal, 3 of which were bilateral. The majority (53 patients; 91.4%) presented with stage pT1 disease (size range, 0.2 to 8 cm), 2 patients presented with pT2 disease (8.5 and 10.3 cm), 1 patient presented with pT3 disease (6.5 cm sarcomatoid RCC focally extending out of the kidney), and pathologic stage was unavailable in 2 cases. Treatment consisted of 29 partial nephrectomies, 26 radical nephrectomies, 2 cryoablations, and 1 cyst ablation. The resection margins were negative in all but one case, with this case disease free after a 26-month period. Two patients had intraoperative tumor disruption and were disease free at 9 and 34 months. Five patients had synchronous ipsilateral renal cell carcinomas (non-CCPRCC). Mean follow-up time was 21 months (range, 1 to 175 mo), with all but 3 patients having no evidence of disease. One patient was presumed to have contralateral disease on the basis of imaging findings and is alive and well 37 months after multiple partial nephrectomies. Metastatic disease to the lung was clinically presumed in 1 patient in whom a higher-grade lesion may have been missed during sampling of the predominantly cystic pT1b tumor and tissue confirmation of the metastases was not obtained. Another case presented with multiple skeletal and pulmonary metastases 8 months after resection of pT3 sarcomatoid CCPRCC. The patient with the sarcomatoid RCC died of multifocal skeletal and pulmonary metastatic disease 13 months after resection of the renal tumor. Our study, the largest to date with follow-up, along with others, suggests that pure CCPRCC is an indolent tumor and should be renamed "clear cell papillary neoplasm of low malignant potential" to reflect their biology.

A shower of second hit events as the cause of multifocal renal cell carcinoma in Tuberous Sclerosis Complex

Abstract: Tuberous sclerosis complex (TSC) is a genetic disorder characterized by seizures and tumor formation in multiple organs, mainly in the brain, skin, kidney, lung and heart. Renal cell carcinoma (RCC) occurs in ∼3% of TSC patients, and typically develops at age 1 tumor. The second (male) TSC patient had bilateral partial nephrectomies (both at age 36), with similar findings of multifocal PRCC. NGS analysis of TSC2 in two of these tumors identified a second hit mutation c.2355+1G>T in one sample that was not seen in other tumors. In conclusion, we report the first detailed genetic analysis of RCCs in TSC patients. Molecular studies indicate that tumors developed independently due to various second hit events, suggesting that these patients experienced a 'shower' of second hit mutations in TSC2 during kidney development leading to this severe phenotype.

Dismantling papillary renal cell carcinoma classification: The heterogeneity of genetic profiles suggests several independent diseases

Abstract: Papillary renal cell carcinoma (pRCC) is the second most frequent renal cell carcinoma (RCC) after clear cell RCC. In contrast to clear cell RCC, there is no consensual protocol using targeted therapy for metastatic pRCC. Moreover, diagnosis of some pRCC, especially pRCC of type 2 (pRCC2) may be challenging. Our aim was to identify molecular biomarkers that could be helpful for the diagnosis and treatment of pRCC. We studied the clinical, histological, immunohistological, and comprehensive genetic features of a series of 31 pRCC including 15 pRCC1 and 16 pRCC2. We aimed to determine whether pRCC represents a unique entity or several diseases. In addition, we compared the genetic features of pRCC2 to those of eight RCC showing various degrees of tubulo-papillary architecture, including three TFE-translocation RCC and five unclassified RCC. We demonstrate that pRCC is a heterogeneous group of tumors with distinct evolution. While most pRCC2 had genetic profiles similar to pRCC1, some shared genomic features, such as loss of 3p and loss of chromosome 14, with clear cell RCC, TFE-translocation RCC, and unclassified RCC. We identified variants of the MET gene in three pRCC1. A mutation in the BRAF gene was also identified in one pRCC1. In addition, using next-generation sequencing (NGS), we identified several variant genes. Genomic profiling completed by NGS allowed us to classify pRCC2 in several groups and to identify novel mutations. Our findings provide novel information on the pathogenesis of pRCC that allow insights for personalized treatment.

Mucinous tubular and spindle cell renal cell carcinoma: a review of clinicopathologic aspects

Abstract: Mucinous tubular and spindle cell renal cell carcinoma is a rare, recently described variant of renal cell carcinoma characterized by an admixture of cuboidal cells in tubules and sheets of spindle cells, and variable amounts of mucinous stroma. It has been recognized as a distinct entity in the 2004 World Health Organization tumor classification. Since then, several dozen of these tumor have been reported with additional complementary morphologic characteristics, immunohistochemical profile, and molecular genetic features that have further clarified its clinicopathologic aspects. Although originally considered as a low grade renal cell carcinoma on the basis of its bland appearing nuclear features and indolent clinical course, mucinous tubular and spindle cell renal cell carcinoma has currently been proven to be a tumor that has a histological spectrum ranging from low to high grade that includes sarcomatoid differentiation. In this review, we present a detailed summary of the current knowledge regarding the clinicopathologic, immunohistochemical, molecular genetic, and prognostic characteristics, as well as differential diagnoses of mucinous tubular and spindle cell renal cell carcinoma.

Identification of Protein Markers Specific for Papillary Renal Cell Carcinoma Using Imaging Mass Spectrometry.

Abstract: Since the emergence of proteomics methods, many proteins specific for renal cell carcinoma (RCC) have been identified. Despite their usefulness for the specific diagnosis of RCC, such proteins do not provide spatial information on the diseased tissue. Therefore, the identification of cancer-specific proteins that include information on their specific location is needed. Recently, matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) based imaging mass spectrometry (IMS) has emerged as a new tool for the analysis of spatial distribution as well as identification of either proteins or small molecules in tissues. In this report, surgical tissue sections of papillary RCC were analyzed using MALDI-IMS. Statistical analysis revealed several discriminative cancer-specific m/z-species between normal and diseased tissues. Among these m/z-species, two particular proteins, S100A11 and ferritin light chain, which are specific for papillary RCC cancer regions, were successfully identified using LC-MS/MS following protein extraction from independent RCC samples. The expressions of S100A11 and ferritin light chain were further validated by immunohistochemistry of human tissues and tissue microarrays (TMAs) of RCC. In conclusion, MALDI-IMS followed by LC-MS/MS analysis in human tissue identified that S100A11 and ferritin light chain are differentially expressed proteins in papillary RCC cancer regions.

Whole lesion quantitative CT evaluation of renal cell carcinoma: differentiation of clear cell from papillary renal cell carcinoma.

Abstract: Purpose Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell cancer (RCC), followed by papillary RCC (pRCC). It is important to distinguish these two subtypes because of prognostic differences and possible changes in management, especially in cases undergoing active surveillance. The purpose of our study is to evaluate the use of voxel-based whole-lesion (WL) enhancement parameters on contrast enhanced computed tomography (CECT) to distinguish ccRCC from pRCC.

Diagnostic approach to hereditary renal cell carcinoma.

Abstract: OBJECTIVE. The purpose of this article is to discuss the histopathologic features, genetics, clinical presentation, and imaging of hereditary renal cancer syndromes. CONCLUSION. Hereditary renal cell carcinoma syndromes can be diagnosed with a pattern-based approach focused on the predominant histologic renal cell carcinoma subtype and associated renal and extrarenal features of each syndrome.

MDCT Findings of Renal Cell Carcinoma Associated With Xp11.2 Translocation and TFE3 Gene Fusion and Papillary Renal Cell Carcinoma

Abstract: OBJECTIVE. The purpose of this study was to compare the MDCT features of renal cell carcinoma (RCC) associated with Xp11.2 translocation and TFE3 gene fusion (Xp11 RCC) and papillary RCC. MATERIALS AND METHODS. The study included 19 and 39 patients with histologically proven Xp11 RCC and papillary RCC, respectively, who underwent multiphase renal MDCT before nephrectomy. CT findings were compared between Xp11 RCC and papillary RCC using the Student t test and chi-square test. Subgroup analyses of small (< 4 cm) renal masses for these features were performed. RESULTS. Patients with Xp11 RCC were younger (p < 0.001), and it was more prevalent in women (p = 0.007). Tumor size was greater in Xp11 RCC (p = 0.004) and more common in cystic change (p < 0.001). Calcification and unenhanced high-attenuating areas were more frequent in Xp11 RCC (p = 0.001 and 0.026, respectively). Xp11 RCCs were more prevalent in lymph node and distant metastasis (p < 0.001 and p = 0.031, respectively). Xp11 RCC and papillary RCC s...

A collision tumor of papillary renal cell carcinoma and oncocytoma: case report and literature review.

Abstract: Objectives The most common renal neoplasms include clear cell, chromophobe, and papillary renal cell carcinomas (PRCCs) and oncocytomas. While lesions containing hybrid features of different tumor types, such as hybrid oncocytic tumors, have been well documented in the literature, the finding of a collision tumor of two distinct tumor types— PRCC and oncocytoma—is extremely rare. Methods We present a case of PRCC associated with an oncocytoma. Our discussion includes a review of the available literature on this rare type of collision tumor. Results Prosection of a partial nephrectomy performed in a 78-year-old man for painless gross hematuria and nocturia revealed a 6.4 × 5 × 3.6-cm well-delineated orange to yellow-tan mass harboring a white-tan 1 × 0.9 × 0.9-cm mass. Histologic diagnosis of PRCC associated with an oncocytoma was rendered. By immunohistochemistry, focal CK7 expression was present in the oncocytoma, while strong diffuse positive CK7 expression was present in the PRCC component. Fluorescence in situ hybridization (FISH) revealed trisomy 17 in 39.3% of PRCC tumor nuclei but no significant chromosomal aberration in oncocytoma. Conclusions In view of this and previously reported cases, thorough sectioning and examination, especially in large oncocytomas, is recommended to exclude the presence of an associated malignancy. To our knowledge, trisomy 17 by FISH has not been previously reported in these extremely rare tumors.

Papillary Renal Cell Carcinoma Seeding along a Percutaneous Biopsy Tract

Abstract: We report a case of tumour seeding caused by percutaneous biopsy of a papillary renal cell carcinoma detected on pathological assessment of the partial nephrectomy specimen in a 50-year-old male. Whilst percutaneous biopsy of renal masses is considered to be safe and can be a valuable tool in the assessment of certain renal lesions, it is not without risks. This rare complication should be taken into consideration before contemplating its use in a patient.

Papillary renal cell carcinoma: a clinicopathological and whole-genome exon sequencing study.

Abstract: Papillary renal cell carcinoma (PRCC) represents the second most common histological subtype of RCC, and comprises 2 subtypes. Prognosis for type 1 PRCC is relatively good, whereas type 2 PRCC is associated with poor clinical outcomes. The aim of the present study was to evaluate the clinicopathological and mutations characteristics of PRCC. Hence, we reported on 13 cases of PRCC analyzed using whole-exome sequencing. Histologically, type 2 PRCC showed a higher nuclear grade and lymphovascular invasion rate versus type 1 PRCC (P < 0.05). Immunostaining revealed type 1 PRCC had higher CK7 and lower Top IIα expression rates (P < 0.05). Whole-exome sequencing data analysis revealed that the mutational statuses of 373 genes (287 missense, 69 silent, 6 nonsense, and 11 synonymous mutations) differed significantly between PRCC and normal renal tissues (P < 0.05). Functional enrichment analysis was used to classify the 287 missense-mutated genes into 11 biological process clusters (comprised of 61 biological processes) and 5 pathways, involved in cell adhesion, microtubule-based movement, the cell cycle, polysaccharide biosynthesis, muscle cell development and differentiation, cell death, and negative regulation. Associated pathways included the ATP-binding cassette transporter, extracellular matrix-receptor interaction, lysosome, complement and coagulation cascades, and glyoxylate and dicarboxylate metabolism pathways. The missense mutation status of 19 genes differed significantly between the groups (P < 0.05), and alterations in the EEF1D, RFNG, GPR142, and RAB37 genes were located in different chromosomal regions in type 1 and 2 PRCC. These mutations may contribute to future studies on pathogenic mechanisms and targeted therapy of PRCC.

Sustained NRF2 activation in hereditary leiomyomatosis and renal cell cancer (HLRCC) and in hereditary tyrosinemia type 1 (HT1)

Abstract: The nuclear erythroid 2-like 2 transcription factor (NRF2), is a major regulator of cellular redox balance. Although NRF2 activation is generally regarded as beneficial to human health, recent studies have identified that sustained NRF2 activation is over-represented in many cancers. This raises the question regarding the role of NRF2 activation in the development and progression of those cancers. This review focuses on the mechanisms and the effects of NRF2 activation in two hereditary cancer predisposition syndromes: hereditary leiomyomatosis and renal cell cancer (HLRCC) and hereditary tyrosinemia type 1 (HT1). Because the cancer initiating mutations in these hereditary syndromes are well defined, they offer a unique opportunity to explore the roles of NRF2 activation in the early stages of carcinogenesis. Over the years, a variety of approaches have been utilized to study the biology of HLRCC and HT1. In HLRCC, in vitro studies have demonstrated the importance of NRF2 activation in sustaining cancer cell proliferation. In the mouse model of HT1 however, NRF2 activation seems to protect cells from malignant transformation. In both HT1 and HLRCC, NRF2 activation promotes the clearance of electrophilic metabolites, enabling cells to survive cancer-initiating mutations. Biological insights gained from the hereditary syndromes’ studies may shed light on to the roles of NRF2 activation in sporadic tumours. * CUL3, : CULLIN 3; FAA, : fumarylacetoacetate; FAH, : fumarylacetoacetate hydrolase gene; FH, : fumarate hydratase; FN, : Fah/Nrf2 double knockout; HCC, : hepatocellular carcinoma; HLRCC, : hereditary leiomyomatosis and renal cell cancer; HPD, : 4-hydroxyphenylpyruvate dioxygenase; Ht1, : hereditary tyrosinemia type 1; KEAP1, : Kelch-like ECH-associated protein 1; LOH, : loss-of-heterozygosity; NRF2, : nuclear erythroid 2-like 2 transcription factor; NTBC, : 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione; PRCC2, : type 2 papillary renal cell carcinoma; ROS, : radical oxygen species; TCA, : tricarboxylic acid

Malignancies arising in allograft kidneys, with a first reported translocation RCC post-transplantation: A case series.

Abstract: Background The increased risk of malignancy in the post-renal transplant population has been well documented. Renal carcinoma is more common in this population, usually arising in native kidneys. Rarely, tumors arise in the transplanted kidney. Our case series reports four cases of malignancy in allograft kidneys, one of which is a first reported case of translocation RCC in a transplanted kidney. Methods The renal transplantation database (1584 patients) at St. Michael's Hospital was reviewed for malignancies arising in allograft kidneys: reports and pathology slides were reviewed. Results Four cases of malignancies arising in the allograft kidney were identified among our kidney transplant population. One patient developed a high grade urothelial carcinoma in the donor kidney post BK virus infection. The other 3 cases were renal cell carcinomas: one clear cell renal cell carcinoma, one translocation renal cell carcinoma, and one papillary renal cell carcinoma. The translocation renal cell cancer had confirmed TFE3 protein over-expression by immunohistochemistry. Molecular testing of the tumors in all 4 cases identified two separate genetic profiles, favored to represent tumors arising from donor tissues along with infiltrating recipient lymphocytes. Discussion Previous reports suggested that epithelial malignancies in allograft kidneys are rare. We identified 4 such tumors in 1584 transplant patients. Further, we identified the first reported case of translocation RCC in an allograft kidney. While the rate of malignancy in allograft kidneys is low, screening of the donor kidneys by ultrasound and/or urine cytology may be of use in detecting these lesions.