Cytomorphology, immunoprofile, and management of renal oncocytic neoplasms.

BACKGROUND: The goal of this study was to evaluate the morphology, immunoprofile, and management of renal oncocytoma (RO), hybrid oncocytic tumor (HOT), and chromophobe renal cell carcinoma (ChRCC). METHODS: Forty-seven cases of RO, 7 cases of HOT, and 25 cases of ChRCC were included in the study. Tissue microarrays were prepared for immunohistochemical evaluation. RESULTS: Large sheets of cells with transverse vessels, and higher nuclear grade were seen more often in ChRCC than in RO or HOT. Tumor cells of RO were more uniform in size and shape relative to HOT and ChRCC. The cytoplasmic features of RO were more uniformly granular relative to HOT and ChRCC, which exhibited variable cytoplasmic features. CK7 and MUC1 were expressed more frequently and diffusely in ChRCC (54% and 94%, respectively) than RO (4% and 52%, respectively) and HOT (0% and 71%, respectively). AMACR and PAX8 were more frequently expressed diffusely in RO (67% and 42%, respectively) than in HOT (0% and 0%, respectively) or ChRCC (14% and 11%, respectively). Most HOT (57%) and CHRCC (60%) patients underwent nephrectomy. Cryoablation was the treatment of choice for 24% of patients with ChRCC, 2% of patients with RO, and 0% of patients with HOT. The majority of patients with RO (88%) opted for active surveillance-a much higher rate than that for patients with HOT (29%) or ChRCC (12%). CONCLUSION: Some cytologic features and immunomarkers are useful in differentiating RO, HOT, and ChRCC. Because no immunomarker or morphologic finding is specific by itself, a combination of morphologic features with immunohistochemistry appears to be the most reliable way to distinguish ChRCC, HOT, and RO on biopsy samples. Subclassification of renal oncocytic tumors into specific categories impacts clinical management and downstream treatment selection.

The classification of pediatric and young adult renal cell carcinomas registered on the children's oncology group (COG) protocol AREN03B2 after focused genetic testing.

BACKGROUND: Renal cell carcinomas (RCCs) are rare in young patients. Knowledge of their pathologic and molecular spectrum remains limited, and no prospective studies have been performed to date in this population. This study analyzes patients diagnosed with RCC who were prospectively enrolled in the AREN03B2 Children's Oncology Group (COG). The objective was to classify these tumors with the aid of focused genetic testing and to characterize their features. METHODS: All tumors registered as RCC by central review were retrospectively re-reviewed and underwent additional ancillary studies. Tumors were classified according to the 2016 World Health Organization classification system when possible. RESULTS: In total, 212 tumors were identified, and these were classified as microphthalmia transcription factor (MiT) translocation RCC (MiT-RCC) (41.5%), papillary RCC (16.5%), renal medullary carcinoma (12.3%), chromophobe RCC (6.6%), clear cell RCC (3.3%), fumarate hydratase-deficient RCC (1.4%), and succinate dehydrogenase-deficient RCC (0.5%). Other subtypes included tuberous sclerosis-associated RCC (4.2%), anaplastic lymphoma kinase (ALK)-rearranged RCC (3.8%), thyroid-like RCC (1.4%), myoepithelial carcinoma (0.9%), and unclassified (7.5%). MiT-RCCs were classified as either transcription factor E3 (TFE3) (93.2%) or EB (TFEB) (6.8%) translocations, and characterization of fusion partners was possible in most tumors. CONCLUSIONS: The current study delineates the frequency of distinct RCC subtypes in a large prospective series of young patients and contributes knowledge to the diagnostic, clinical, and genetic features of MiT-RCC, the most common subtype among this age group. The identification of rare subtypes expands the spectrum of RCC in young patients, supporting the need for a thorough diagnostic workup. These studies may aid in the introduction of specific therapies for different RCC subtypes in the future. Cancer 2018. © 2018 American Cancer Society.

ALK-rearranged renal cell carcinomas in children.

Knowledge of the clinicopathological and molecular spectrum of pediatric renal cell carcinomas (RCC) remains limited, and approximately 16%-24% of these neoplasms cannot be classified into specific subtypes. In this review of 168 pediatric RCC prospectively registered on Children's Oncology Group AREN03B2 protocol, six RCC (3.5%) that demonstrated a unique epithelioid morphology and a peculiar immunophenotypic profile that includes expression of ALK, TFE3, and retention of INI1 was identified. Further investigation revealed ALK rearrangements in all cases, manifested molecularly by fusion transcripts of either VCL-ALK (3 patients all with sickle cell trait which had been previously reported) or TPM3-ALK (3 patients, none with sickle cell trait). Based on the shared unique morphologic, immunophenotypic, and genetic features, it was proposed that these neoplasms belonged to a distinct subgroup of RCC frequently occurring in pediatric patients, which they have termed as ALK-rearranged RCC. Importantly, additional therapeutic options may be available for these patients.

Expanding the Spectrum of Renal Tumors in Children: Primary Renal Myoepithelial Carcinomas With a Novel EWSR1-KLF15 Fusion.

We report the first 2 examples of primary renal myoepithelial carcinoma (MEC), both occurring in children. Both tumors had the unique morphologic features, immunophenotype, and EWSR1 gene rearrangements supporting the diagnosis. In keeping with the previous observations of an aggressive behavior in pediatric MEC, both cases presented with advanced local stage and distant metastases at the time of diagnosis. The EWSR1 translocation partner was identified as the Kruppel-like factor 15 (KLF15) gene in both tumors, and the novel EWSR1-KLF15 gene fusion transcripts were verified using reverse transcription polymerase chain reaction and Sanger dideoxy sequencing. So far, a role for KLF15 in carcinogenesis has not been established, in contrast to other members of the Kruppel-like family of transcription factors, and no rearrangements involving this gene have been documented to our knowledge. These findings expand the spectrum of pediatric renal tumors to include MEC. The characterization of novel EWSR1-KLF15 fusion transcripts carries important diagnostic implications, as well as clues to understand the pathogenesis of these neoplasms.

Immunoexpression of napsin A in renal neoplasms.

BACKGROUND: Immunohistochemistry (IHC) for napsin A has been widely used to support a diagnosis of lung adenocarcinoma with high sensitivity. In this study, we evaluated immunoreactivity for napsin A in a broad spectrum of renal neoplasms by using tissue microarrays (TMA). METHODS: Duplicate TMA of 159 surgically excised renal neoplasms of various types were constructed. IHC for napsin A was performed on TMAs with appropriate positive and negative controls. RESULTS: Napsin A was expressed in Acquired cystic disease associated renal cell carcinoma (RCC) (2/2, 100.0%), chromophobe RCC (5/45, 11.1%), clear cell RCC (10/23, 43.5%), clear cell papillary RCC (9/19, 47.4%), metanephric adenoma (3/3, 100.0%), oncocytoma (13/23, 56.5%), and papillary RCC (31/37, 83.8%). Expression of napsin A was not seen in mucinous tubular and spindle cell carcinoma (0/1, 0.0%), TFE/MITF RCC 0/1, 0.0%), and urothelial carcinoma (0/6, 0.0%). CONCLUSIONS: Napsin A is expressed in both common and rare sub-types of renal neoplasms with variable sensitivity. Based on our results, napsin A is not specific for lung adenocarcinoma. When a metastatic carcinoma of unknown primary is positive for napsin A, the differential diagnosis should include tumors of both renal and lung origin. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9558727831304717 .

The utility of p63, p40, and GATA-binding protein 3 immunohistochemistry in diagnosing micropapillary urothelial carcinoma.

Micropapillary urothelial carcinoma (MPUC) is an uncommon variant of urothelial carcinoma (UC) with an aggressive clinical course. There have been limited studies on the UC markers GATA-binding protein 3 (GATA3), p63, and p40 in MPUC. Our study investigated the immunoreactivity of these 3 markers in MPUC compared with conventional UC of different grades and stages. Immunohistochemistry was performed on 62 cases of high-grade urothelial carcinoma (HGUC), 16 low-grade urothelial carcinoma (LGUC), and 20 MPUC. p63 expression was strong and diffuse in all LGUC, significantly decreased in high stage and HGUC, and virtually absent in MPUC. p40 expression was decreased in HGUC and markedly decreased in MPUC relative to LGUC. These results suggest that loss of p63 expression in a UC appears to be associated with adverse features--including cases with micropapillary differentiation. Decreased GATA3 expression was seen frequently in high-grade and high-pathologic stage (≥pT2) tumors but was retained in MPUC cases. The findings of retained GATA3 expression in MPUC, which often shows a loss of expression of other urothelial markers such as p63, may be helpful for determining the origin of micropapillary carcinoma of unknown primary. Compared with the traditional markers p63 and p40, GATA3 is the most sensitive marker of conventional UC and MPUC.

Diagnostic accuracy of frozen-section analysis of cancer-containing bladder transurethral resection specimens for the presence of muscularis propria invasion.

AIMS: Frozen section (FS) consultation is generally an accurate diagnostic modality. At our institution, we are frequently asked to assess transurethral resection specimens (TURBT) at FS for muscularis propria (MP) invasion by carcinoma. This study documents our experience in evaluating cancer-containing TURBT specimens at FS for MP invasion. METHODS: 32 TURBT sent for FS from 2008-2010 were identified. The FS and permanent section (PS) diagnoses were reviewed. Cases excluded from the calculation of test performance included: (1) cases without cancer on FS or PS slides, (2) FS diagnosis deferred, (3) cases without MP on FS and subsequent PS slides. Sensitivity (SEN), specificity (SPEC), positive predictive value (PPV), and negative predictive value (NPV) for identifying MP invasion at FS were calculated. RESULTS: In 6 cases, no cancer was present in FS or PS slides (18%). The FS diagnosis was deferred on 3 cases (9%). In one case (3%) MP was not present in the FS or the subsequent PS slides. Of the remaining 22 cases, 2 false positive and 6 false negative diagnoses of MP invasion were identified. The test performance for FS assessment of MP invasion in TURB were SEN=33%, SPEC=84%, PPV=60%, and NPV=64%. CONCLUSIONS: Identifying MP invasion on PS can be difficult, and our results suggest that this is more difficult at FS. Though this study is based on small numbers, our results point to the conclusion that examination of TURBT specimens for MP invasion is best done on PS.

Non-mass-associated intraductal papillomas: is excision necessary?

Intraductal papillomas (IDPs) of the breast can be associated with a variety of clinical symptoms and radiologic findings. Surgical excision is often recommended based on the possibility of an associated high-grade lesion. Although the rate of upgrades has been extensively evaluated for IDPs, many studies are hindered by broad inclusion criteria, a lack of pathologic-radiologic concordance, and no standard definition of what constitutes an upgrade. In the current study, we evaluate the risk of upgrade for a specific subset of IDPs: non-mass-associated IDPs. We identified all breast needle core biopsies with a diagnosis of IDP between 2003 and 2010. Patients with associated masses, architectural distortion, or ipsilateral breast cancer were excluded. All needle core biopsy slides and relevant imaging studies were reviewed to ensure pathologic-radiologic concordance. Excision pathology was also reviewed; an upgrade was defined as the presence of ductal carcinoma in situ or invasive carcinoma in the excision. Seventy-nine IDPs that met inclusion criteria were identified and were further divided into 3 histologic categories: micropapilloma, fragmented IDP, and atypical IDP. Micropapillomas and fragmented IDPs had no upgrades (0/37). In patients who did not undergo excision, none subsequently developed ipsilateral breast cancer (follow-up, 50-61 months). This is in contrast to atypical IDPs that had a 33% upgrade rate. One patient with an unexcised atypical IDP developed ipsilateral breast cancer within 2 years. Our data suggest that conservative follow-up is reasonable for non-mass-associated IDPs without atypia regardless of microscopic size, provided that careful pathologic-radiologic correlation is achieved.

Differential diagnosis of renal tumors with clear cytoplasm: clinical relevance of renal tumor subclassification in the era of targeted therapies and personalized medicine.

CONTEXT: The World Health Organization classification of renal tumors synthesizes morphologic, immunohistochemical, and molecular findings to define more than 40 tumor types. Of these, clear cell (conventional) renal cell carcinoma is the most common malignant tumor in adults and-with the exception of some rare tumors-the most deadly. The diagnosis of clear cell renal cell carcinoma on morphologic grounds alone is generally straightforward, but challenging cases are not infrequent. A misdiagnosis of clear cell renal cell carcinoma has clinical consequences, particularly in the current era of targeted therapies. OBJECTIVE: To highlight morphologic mimics of clear cell renal cell carcinoma and provide strategies to help differentiate clear cell renal cell carcinoma from other renal tumors and lesions. The role of the pathologist in guiding treatment for renal malignancies will be emphasized to stress the importance of proper tumor classification in patient management. DATA SOURCES: Published literature and personal experience. CONCLUSIONS: In challenging cases, submission of additional tissue is often an inexpensive and effective way to facilitate a correct diagnosis. If immunohistochemical stains are to be used, it is best to use a panel of markers, as no one marker is specific for a given renal tumor subtype. Selection of limited markers, based on a specific differential diagnosis, can be as useful as a large panel in reaching a definitive diagnosis. For renal tumors, both the presence and absence of immunoreactivity and the pattern of labeling (membranous, cytoplasmic, diffuse, focal) are important when interpreting the results of immunohistochemical stains.

Primary adenocarcinoma of the urinary bladder: differential diagnosis and clinical relevance.

CONTEXT: Glandular lesions of the urinary bladder include a broad spectrum of entities ranging from completely benign glandular lesions to primary and secondary malignancies. Common benign bladder lesions that exhibit glandular differentiation include cystitis cystica, cystitis glandularis, von Brunn nests, nephrogenic adenoma, intestinal metaplasia, urachal remnant, endometriosis, and prostatic-type polyp. The World Health Organization defines primary adenocarcinoma of the bladder as an epithelial malignancy with pure glandular differentiation without evidence of typical urothelial carcinoma. Malignant lesions that should be included in the differential diagnosis of a primary adenocarcinoma of the bladder include noninvasive and invasive urothelial carcinoma with glandular differentiation and secondary malignancies involving the bladder by direct extension or metastasis. The recognition and distinction of these different entities may be a challenge for pathologists, but they are of great clinical importance. OBJECTIVE: To review features of primary bladder adenocarcinoma as well as those entities that need to be differentiated from primary bladder adenocarcinoma, with emphasis on clinical findings, pathologic characteristics, and immunoprofiles. DATA SOURCES: Selected original articles published in the PubMed service of the US National Library of Medicine. CONCLUSIONS: The accurate diagnosis of adenocarcinoma of the urinary bladder is important and challenging. It has to prompt an extensive clinical workup to rule out other glandular lesions in the urinary bladder, especially the possibility of secondary involvement of the bladder by an adenocarcinoma from a different site.

Urine cytomorphology of micropapillary urothelial carcinoma.

Micropapillary urothelial carcinoma (MPUC) is a rare subtype of urothelial carcinoma (UC) with an aggressive clinical course. The cytomorphologic features of MPUC in urine cytology have not been well described. In this study, 23 urine specimens (11 voided urines and 12 bladder washings) from 23 patients with MPUC on follow-up surgical material and 28 specimens (14voided urines and 14 bladder washings) from 28 patients with high-grade UCs (HGUC) were retrieved. Cytologic features (nuclear grade, cytoplasmic characteristics), architectural features (single cell pattern, true papillary structures, flat sheets/nests, three dimensional clusters, micropapillary (inside-out, acinar-like, or cauliflower with nuclei located peripherally)), and necrosis were evaluated. Clinical follow-up was obtained by chart review. Two findings, micropapillae and cytoplasmic vacuoles, were seen more frequently in MPUC compared to HGUC, 81.0% vs. 14.3%, and 57.1% vs. 14.3%, respectively. The combination of these two findings had a sensitivity of 78%, a specificity of 86%, a positive predictive value of 82%, and a negative predictive value of 83% for the diagnosis of MPUC on subsequent biopsy. MPUC and HGUC can both exhibit a single cell pattern, papillary structures, flat sheets/nests, three dimensional clusters, high-nuclear grade, and necrosis, thus these findings are not useful in distinguishing these entities. Chart review revealed that patients with MPUC had a higher rate of metastasis to lymph nodes and distant organs than HGUC, 57% vs. 4%. Therefore, the findings of cytoplasmic vacuoles and micropapillary structures in UC from a urine cytology specimen are associated with MPUC on subsequent biopsy.

Clear-cell papillary renal cell carcinoma: molecular and immunohistochemical analysis with emphasis on the von Hippel-Lindau gene and hypoxia-inducible factor pathway-related proteins.

Over the past few years several investigators have independently described unique low-grade renal epithelial neoplasms with clear cytoplasm, focal to diffuse papillary architecture, and occasional leiomyomatous stromal metaplasia that are not currently recognized in the World Health Organization classification of renal tumors. These tumors have been referred to by a variety of names including clear-cell papillary renal cell carcinoma and recently "clear-cell tubulopapillary renal cell carcinoma". On the basis of the available data, such tumors are positive for cytokeratin 7 (CK7) and carbonic anhydrase IX (CA9), while being negative for CD10, α-methylacyl-CoA racemase (AMACR), and TFE3. These tumors reportedly lack trisomies of chromosomes 7 and 17, deletions of 3p25, von Hippel-Lindau (VHL) gene mutations, and VHL promoter hypermethylation. Herein, we report on nine cases of this tumor emphasizing detailed studies of the VHL gene and hypoxia-inducible factor (HIF) pathway. Molecular studies performed included VHL mutational analysis, copy number changes assessed using single-nucleotide polymorphism arrays, and qRT-PCR for VHL mRNA expression. Immunohistochemical stains for markers of HIF pathway activation (HIF-1α, CA9, and glucose transporter-1 (GLUT-1)) as well as other relevant markers (CK7, CD10, AMACR, and TFE3) were performed. None of our tumors harbored VHL gene mutations, losses of chromosomal region 3p25, or trisomies of chromosomes 7 or 17. VHL mRNA was overexpressed in our tumors relative to normal renal tissue and clear-cell renal cell carcinoma. All cases showed strong co-expression of CK7, HIF-1α, GLUT-1, and CA9. No expression of TFE3, CD10, or AMACR was seen. The morphological, immunophenotypic, and molecular features of these unique low-grade tumors are sufficiently distinct to allow separation from other renal cell carcinoma subtypes. The co-expression of CA9, HIF-1α, and GLUT-1 in the absence of VHL gene alterations in clear-cell papillary renal cell carcinoma suggests activation of the HIF pathway by non-VHL-dependent mechanisms.

Pathologic Features of Adult Renal Cortical Tumors.

In the past few years, a much better understanding of the morphologic spectrum of renal cortical tumors has resulted in a clinically highly relevant contemporary classification system of these tumors. The current and still evolving era of targeted therapies in kidney cancer further highlights the importance of the appropriate pathologic classification. The recently gained knowledge about molecular-driven antigen expression almost certainly will have a major role to play in the characterization, development, and evaluation of targeted therapies in kidney cancer in the future.