Testicular Cancer: Contemporary Updates in Staging.

Testicular tumors are the most common solid tumors in young men, the vast majority of which are of germ cell origin. The staging of human cancers is paramount to correct patient management. Staging systems have passed through several developments leading to the release of the most recent 8th edition of the American Joint Committee for Cancer (AJCC) staging manual, which is based on the current understanding of tumor behavior and spread. In this review, the authors summarize the current AJCC staging of the germ cell tumors, highlight essential concepts, and provide insight into the most important parameters of testicular tumors.

Diagnostic approach in TFE3-rearranged renal cell carcinoma: a multi-institutional international survey.

Transcription factor E3-rearranged renal cell carcinoma (TFE3-RCC) has heterogenous morphologic and immunohistochemical (IHC) features.131 pathologists with genitourinary expertise were invited in an online survey containing 23 questions assessing their experience on TFE3-RCC diagnostic work-up.Fifty (38%) participants completed the survey. 46 of 50 participants reported multiple patterns, most commonly papillary pattern (almost always 9/46, 19.5%; frequently 29/46, 63%). Large epithelioid cells with abundant cytoplasm were the most encountered cytologic feature, with either clear (almost always 10/50, 20%; frequently 34/50, 68%) or eosinophilic (almost always 4/49, 8%; frequently 28/49, 57%) cytology. Strong (3+) or diffuse (>75% of tumour cells) nuclear TFE3 IHC expression was considered diagnostic by 13/46 (28%) and 12/47 (26%) participants, respectively. Main TFE3 IHC issues were the low specificity (16/42, 38%), unreliable staining performance (15/42, 36%) and background staining (12/42, 29%). Most preferred IHC assays other than TFE3, cathepsin K and pancytokeratin were melan A (44/50, 88%), HMB45 (43/50, 86%), carbonic anhydrase IX (41/50, 82%) and CK7 (32/50, 64%). Cut-off for positive TFE3 fluorescent in situ hybridisation (FISH) was preferably 10% (9/50, 18%), although significant variation in cut-off values was present. 23/48 (48%) participants required TFE3 FISH testing to confirm TFE3-RCC regardless of the histomorphologic and IHC assessment. 28/50 (56%) participants would request additional molecular studies other than FISH assay in selected cases, whereas 3/50 participants use additional molecular cases in all cases when TFE3-RCC is in the differential.Optimal diagnostic approach on TFE3-RCC is impacted by IHC and/or FISH assay preferences as well as their conflicting interpretation methods.

Immunophenotypic Characterization of Germ Cell Tumor-Derived Primitive Neuroectodermal Tumors: Evidence for Frequent Neuronal and/or Glial Differentiation.

CONTEXT.­: Primitive neuroectodermal tumors (PNETs) may arise as a somatic-type malignancy in germ cell tumors. In this setting, most PNETs resemble those of the central nervous system and lack chromosome 22 translocations. However, description of the morphologic and differentiation spectrum of PNETs arising from germ cell tumors is lacking. OBJECTIVE.­: To investigate the morphologic and immunohistochemical features of these tumors, concentrating on neuronal and glial features. DESIGN.­: We selected cases based on a morphologically identifiable glial and/or differentiated neuronal component in association with the undifferentiated PNET. Immunohistochemistry for glial fibrillary acidic protein, S100 protein, synaptophysin, chromogranin A, and SOX11 was performed on tumors with available material, with the scoring of both staining intensity (0-3) and extent (0-3). Thirteen qualifying PNETs of testicular origin with available immunohistochemical stains or stainable material were identified. The complete stain panel was performed in 10 tumors. RESULTS.­: SOX11 demonstrated positive staining in the undifferentiated PNET component of all tumors (10 of 10) and was rarely positive in the differentiated (ie, neuronal/glial) component (1 of 10; focal and weak); synaptophysin was slightly less sensitive in the undifferentiated component (12 of 13; often focal and weak) and also showed positivity in the neuronal/glial component (5 of 13). Glial fibrillary acidic protein and S100 were more frequently positive in the differentiated areas (83% and 77%, respectively) compared with undifferentiated areas (25% and 17%, respectively). CONCLUSIONS.­: SOX11 is a sensitive immunohistochemical marker for testicular PNET, particularly those lacking differentiation. Testicular PNETs often demonstrate glial and/or neuronal differentiation. Differentiation is marked by the acquisition of S100 and glial fibrillary acidic protein expression and SOX11 loss.

Practical Molecular Testing in a Clinical Genitourinary Service.

CONTEXT.­: Molecular testing is increasingly playing a key role in the diagnosis, prognosis, and treatment of neoplasms of the genitourinary system. OBJECTIVE.­: To provide a general overview of the clinically relevant molecular tests available for neoplasms of the genitourinary tract. DATA SOURCES.­: Relevant medical literature indexed on PubMed. CONCLUSIONS.­: Understanding of the molecular oncology of genitourinary neoplasms is rapidly advancing, and the pathologist must be aware of the practical implications of molecular testing. While many genomic abnormalities are not yet clinically relevant, there is an increasing library of ancillary tests that may guide diagnosis, prognosis, and/or treatment of many neoplasms. Recurrent genomic abnormalities have been identified in many types of renal cell carcinoma, and some types of renal cell carcinoma are specifically defined by the molecular abnormality. Two major routes of developing urothelial carcinoma have been molecularly described. Recurrent translocations involving ETS family genes are found in approximately half of prostate cancer cases. Testicular germ cell tumors typically harbor i(12p). Penile neoplasms are often high-risk human papillomavirus-driven cancers. Nonetheless, even as genitourinary neoplasms are increasingly better understood at the molecular level, further research with eventual clinical validation is needed for optimal diagnosis, prognosis, and treatment of aggressive malignancies in the genitourinary tract.

Prostate Specific Membrane Antigen Targeted Positron Emission Tomography of Primary Prostate Cancer: Assessing Accuracy with Whole Mount Pathology.

PURPOSE: We evaluated which lesions are detected and missed on [68Ga]Ga-PSMA (prostate specific membrane antigen)-11 positron emission tomography in patients with primary prostate cancer. MATERIALS AND METHODS: Patients undergoing radical prostatectomy were enrolled in this prospective observational study. Patients underwent [68Ga]Ga-PSMA-11 positron emission tomography/computerized tomography or positron emission tomography/magnetic resonance imaging prior to surgery and received a dose of [68Ga]Ga-PSMA-11 intraoperatively for positron emission tomography of extirpated specimens. Whole mount pathology was performed with lesion and intralesion based analysis to determine the characteristics of lesions detected or not detected by PSMA positron emission tomography. Lesion volume was determined by planimetry and clinically significant lesion volume was calculated as lesion volume × fraction pattern 4/5. RESULTS: On whole mount analysis 30 cancerous lesions were found in a total of 15 patients, including 4, 15, 4, 1 and 6 which were Grade Group 1, 2, 3, 4 and 5, respectively. PSMA-positron emission tomography detected 100% of primary/index lesions and 8 of 11 (82%) secondary lesions. All Grade Group 3-5 lesions were detected vs 12 of 15 Grade Group 2 lesions. When comparing Grade Group 2 vs 3-5, lesion size was similar (p=0.48) but the standardized uptake value was lower for Grade Group 2 vs 3-5 (5.3 vs 7.9, p=0.03). The 3 missed lesions showed 10% or less of pattern 4 and a Gleason pattern 4/5 volume of less than 0.1 cm3. CONCLUSIONS: PSMA positron emission tomography detected 100% of primary/index lesions in this study. The 3 missed secondary lesions were small and had a low percent of pattern 4. This argues for further study to better understand what defines clinically significant prostate cancer, which would assist in determining whether small lesions that become challenging to detect by [68Ga]Ga-PSMA-11 positron emission tomography confer a risk to the patient.

MYB-NFIB gene fusion in prostatic basal cell carcinoma: clinicopathologic correlates and comparison with basal cell adenoma and florid basal cell hyperplasia.

Prostatic basal cell carcinoma is a malignant neoplasm composed of basaloid cells forming infiltrative nests and tubules, which may potentially be misdiagnosed as benign basal cell proliferations (i.e., florid basal cell hyperplasia or basal cell adenoma) and also closely resembles adenoid cystic carcinoma of the salivary gland. MYB-NFIB gene rearrangement occurs in 30-86% of salivary gland adenoid cystic carcinomas. We sought to further characterize MYB gene rearrangement in prostatic basal cell carcinoma and correlate MYB-NFIB fusion status with other clinicopathologic characteristics. To this end, FISH analysis for MYB-NFIB gene fusion using fusion probes was performed on formalin-fixed, paraffin-embedded tissue sections from prostatic basal cell carcinoma (n = 30), florid basal cell hyperplasia (n = 18), and basal cell adenoma (n = 4). Fourteen of 30 (47%) cases of basal cell carcinoma were positive for MYB-NFIB gene fusion FISH, and no cases of benign basal cell proliferations were positive (p < 0.05). FISH-positive patients (mean age = 63 years, range: 35-81) tended to be younger than FISH-negative patients (mean age = 70 years, range: 55-93). Most FISH-positive cases demonstrated adenoid cystic carcinoma-like morphology (57%), and most FISH-negative cases demonstrated nonadenoid cystic carcinoma-like morphology (93%); one case (FISH-positive) demonstrated areas with both adenoid cystic carcinoma-like and nonadenoid cystic carcinoma-like morphology. FISH-positive cases more frequently demonstrated perineural invasion (50% vs. 14%, p < 0.05) compared to FISH-negative cases. Conversely, tall basal cells (i.e., neoplastic cells at least two times taller than wide) were more frequent in FISH-negative cases than FISH-positive cases (93% vs. 36%, p < 0.05). Approximately, 50% of prostatic basal cell carcinoma harbor MYB-NFIB gene fusion. The majority of these cases were characterized by adenoid cystic carcinoma-like morphology, perineural invasion, and lack tall basal cells. Florid basal cell hyperplasia and basal cell adenoma are negative for MYB-NFIB gene fusion.

Clinicopathological characteristics of ypT0N0 urothelial carcinoma following neoadjuvant chemotherapy and cystectomy.

AIMS: To describe a large tertiary care academic centre's experience with patients who achieve a complete pathological response (ie, ypT0N0) following neoadjuvant chemotherapy (NAC) and radical cystectomy (RC) with emphasis on morphological features present in the RC and clinical outcome. METHODS: 41 patients with ypT0N0 disease following transurethral resection of bladder tumour (TURBT), NAC and RC with available clinical follow-up information were analysed. Slides from all RCs were reviewed to confirm pathological stage and assess for morphological parameters (eg, foreign body giant cell reaction, dystrophic calcification, scar and fat necrosis). RESULTS: With median follow-up of 32.8 months, the recurrence-free survival at 1 and 5 years was 97.4% and 93.5%, while the overall survival at 3 and 5 years was 94.2% and 88.6%, respectively. No patients died of urothelial carcinoma. Stage assigned at TURBT was 1 pTa (2%), 1 pT1 (2%), 38 pT2 (93%) and 1 pT3a (2%). 17 TURBTs demonstrated variant histology, with the majority of these being squamous (65%). The most common morphological features present at RC were scar (100%), foreign body giant cell reaction (80%), chronic inflammation within lamina propria (68%) and dystrophic calcifications (39%). Other morphological features were less common or absent. CONCLUSION: ypT0N0 disease at RC portends an excellent prognosis, regardless of stage or variant histology in the TURBT; scar, foreign body giant cell reaction, chronic inflammation and dystrophic calcifications are often present.

Cytomorphologic comparison of type 1 and type 2 papillary renal cell carcinoma: A retrospective analysis of 28 cases.

BACKGROUND: Papillary renal cell carcinoma (pRCC) is classified as type 1 or type 2 on the basis of histomorphologic features. Type 1 pRCC typically carries a better prognosis, and renal cell carcinoma is often diagnosed by fine-needle aspiration (FNA). Thus, this study was designed to characterize cytomorphologic features present in FNA cases that could be used to discriminate between type 1 and type 2 pRCC. METHODS: Electronic records of Indiana University were searched for pRCC FNA cases (2007-2018). Corresponding surgical pathology reports were reviewed to classify patients as having type 1 or type 2 pRCC. FNA slides were reviewed to assess cytomorphologic features (ie, nuclear grade; cell size; cytoplasmic volume and quality; and the presence of single cells, papillary clusters, nuclear grooves, foamy histiocytes, hemosiderin pigment, psammoma bodies, and hyaline globules). A semiquantitative score was assigned to each feature. The nuclear grade was assigned with the World Health Organization/International Society of Urological Pathology grading system. The cytomorphologic features of type 1 and type 2 pRCC were compared. RESULTS: Sixteen patients with type 1 pRCC and 12 patients with type 2 pRCC were included in the study. Type 2 pRCC had a higher nuclear grade, a higher volume of cytoplasm, and more granular cytoplasm. Type 1 pRCC more frequently had nuclear grooves and clear cytoplasm. The remaining features (ie, cell size, papillary clusters, single cells, foamy histiocytes, hemosiderin pigment, psammoma bodies, and hyaline globules) were not statistically significant. CONCLUSIONS: Nuclear grade, cytoplasmic volume and granularity or clarity, and nuclear grooves are cytomorphologic features that may aid in the distinction between type 1 and type 2 pRCC.

Clinical utility and concordance of upper urinary tract cytology and biopsy in predicting clinicopathological features of upper urinary tract urothelial carcinoma.

Five percent of urothelial carcinoma occurs in the upper urinary tract (UUT), a challenging location to biopsy. We aim to evaluate concordance between biopsy, cytology, and resection specimens in a large upper tract urothelial carcinoma (UTUC) cohort. One hundred seventeen UTUC resections with UUT biopsy and/or cytology specimens from 2000 to 2016 were retrieved; pathologic material was re-reviewed, evaluated for concordance, and correlated with clinical information. Fourteen percent of preoperative biopsies, including 8 from the renal pelvis and 6 from the ureter, lacked neoplastic diagnoses. Seventy-seven percent of diagnostic biopsies included subepithelial tissue; 11% demonstrated reclassification of grade and 30% demonstrated reclassification of invasion status. Twenty-six percent of renal pelvis UTUC and 36% of ureter UTUC were invasive only on resection. Of 18 UTUCs reclassified from noninvasive high-grade papillary urothelial carcinoma to invasive high-grade papillary urothelial carcinoma, 39% had prior radical cystectomy (versus 8% invasive UTUC and 11% noninvasive UTUC with concordant biopsies). Most high-grade UTUC (88%) and some low-grade UTUC (58%) resections had abnormal cytology results. Biopsy-resection pairs with concordant invasion status and pairs with discordant invasion status showed similar rates of recurrence (38% versus 38%) and metastasis (25% versus 27%). Fourteen percent of UUT biopsies lacked diagnostic neoplastic material. Grade concordance between biopsy and resection was high (89%), but 30% of cases showed invasion only on resection. Subepithelial tissue was less commonly present in ureter biopsies, particularly from the midureter or proximal ureter. UTUC in patients with prior cystectomy were more likely to show invasion on resection but not biopsy.

The utility of upper urinary tract urine cytology before and after application of the Paris system.

BACKGROUND: The Paris System (TPS) introduced diagnostic criteria for urine cytology to improve reproducibility among pathologists. Thus far, most cytology studies have investigated application of TPS on lower urinary tract specimens. Also, it is unclear which cytologic features are most predictive of malignancy, particularly in the upper urinary tract. We evaluate concordance rates of preoperative upper urinary tract cytology specimens before and after application of TPS criteria with surgical resections and assess cytologic features associated with malignancy. DESIGN: 54 resections with high- and low-grade urothelial carcinoma (HGUC, LGUC) from 2000-2016 with available preoperative cytology (n = 61) were identified. Cytology was re-reviewed to evaluate cytologic features and provide diagnoses before and after TPS implementation. RESULTS: The most common cytologic features associated with HGUC were N:C ratios ≥0.7 (88%), hyperchromasia (83%), coarse chromatin distribution (67%), and nuclear pleomorphism in cell clusters (65%). Application of TPS criteria resulted in 10 diagnostic downgrades and 6 diagnostic upgrades. After TPS criteria were applied, the sensitivity of a positive diagnosis decreased from 29% to 19%. The morphologic feature most consistently associated with a downgrade from positive to suspicious was a lack of marked nuclear contour irregularities in atypical urothelial cells. CONCLUSION: Using strict TPS criteria in upper urinary tract cytology specimens may decrease the frequency of positive diagnoses with a concurrent increase in suspicious diagnoses. These findings may indicate that different morphologic features, particularly markedly irregular nuclear contours, may have different predictive values for HGUC in upper urinary tract cytology specimens compared with those from the lower urinary tract.

Staging of bladder cancer.

Urothelial carcinoma of the urinary bladder is a heterogeneous disease with multiple possible treatment modalities and a wide spectrum of clinical outcome. Treatment decisions and prognostic expectations hinge on accurate and precise staging, and the recently published American Joint Committee on Cancer (AJCC) Staging Manual, 8th edition, should be the basis for staging of urinary bladder tumours. It is unfortunate that the International Union Against Cancer (UICC) 8th edition failed to incorporate new data which is considered in the AJCC 8th edition. Thus, the AJCC 8th edition is the focus of this review. Several critical changes and clarifications are made by the AJCC 8th edition relative to the 7th edition. Although the most obvious changes in the 8th edition are in the N (i.e. perivesical lymph node involvement now classified as N1) and M (i.e. M1 is subdivided into M1a and M1b) categories, several points are clarified in the T category (e.g. substaging of pT1 should be attempted). Further optimisation, however, is required. No particular method of substaging pT1 is formally recommended. In this review, these modifications are discussed, as well as points, which require further study and optimisation.

Updates in Staging and Reporting of Testicular Cancer.

The American Joint Committee for Cancer eighth edition staging manual incorporated several critical changes regarding staging of testis germ cell tumors, and these changes are summarized and discussed in this article. Further challenges, however, remain, and these are also highlighted.

The utility of SDHB and FH immunohistochemistry in patients evaluated for hereditary paraganglioma-pheochromocytoma syndromes.

A significant portion of paragangliomas (PGL) and pheochromocytomas (PCC) occur in patients with hereditary PGL/PCC syndromes, including those with germline mutations in succinate dehydrogenase (SDHx) subunit genes. Recently, germline fumarate hydratase (FH) mutations have been identified in a subset of PGL/PCC, and patients with hereditary leiomyomatosis and renal cell carcinoma (HLRCC) may have an increased risk of developing PGL/PCC. SDHB immunohistochemistry (IHC) has previously been shown to be useful for identifying SDHx-deficient PGL/PCC, however, FH IHC has never been explored in these tumors. Thus, we characterized SDHB and FH IHC in a large cohort of PGL/PCC patients (n = 41) at our institution who were evaluated for hereditary PGL/PCC syndromes. Overall, there was strong, positive correlation between germline SDHx subunit gene mutation status and SDHB IHC status (rφ = 0.77; P < .0001), with high corresponding sensitivity, specificity, positive predictive value, and negative predictive value (95.0%, 81.8%, 82.6%, and 94.7%, respectively). Although SDHB loss by IHC was highly correlated with germline SDHx gene mutations, its utility in this population was dependent on clinicopathologic context: while all head and neck PGL patients with SDHB-deficient tumors had germline SDHx gene mutations, only a small subset (25.0%) of PCC patients with SDHB-deficient tumors harbored a germline SDHx gene mutation. Finally, although our cohort contained only one HLRCC patient, their tumor was FH-deficient by IHC, and all other PGL/PCC showed retained FH IHC. Thus, in the appropriate clinical setting, SDHB and FH IHC may be useful for identifying PGL/PCC patients for Medical Genetics evaluation.

Ordering Stains That Aren't Indicated.

The pathologist rarely interacts with patients face-to-face, but he or she nonetheless maintains a crucial relationship with the patient (i.e., the patient-pathologist relationship). A more tangible relationship, the pathologist-clinician relationship, is typically augmented by the patient-pathologist relationship, but at times the two distinct relationships are at odds, creating ethical dilemmas for the pathologist. This case study and discussion highlight some of these potential ethical questions and underscore the need for pathologists and clinicians to have cooperative, collaborative, and professional relationships. Pathologists should feel empowered to guide the clinician's use of appropriate clinical testing to ensure proper management of the patient and responsible use of health care resources.

Metastatic ductal carcinoma of the breast to the thyroid gland diagnosed with fine needle aspiration: A case report with emphasis on morphologic and immunophenotypic features.

Metastases to the thyroid are uncommon [<0.2% of thyroid fine needle aspirations (FNA)]. Of metastases to the thyroid, breast carcinoma is relatively common. The diagnosis of metastasis to the thyroid has important therapeutic and prognostic implications. To our knowledge, a morphologic and immunophenotypic comparison of metastatic ductal carcinoma of the breast and primary thyroid carcinomas has not been reported. Here, we report the case of a 37-year-old female with a history of metastatic ductal carcinoma of the breast (modified Bloom-Richardson grade 2; ER+, PgR+, HER2+) diagnosed 6 years prior. She developed hoarseness, prompting a CT scan. Multiple thyroid nodules were found, including a 1.5 cm hypoechoic, solid, irregularly-shaped nodule. On FNA, cells were arranged singly and in crowded groups, varied in size and degree of pleomorphism, and exhibited rare nuclear grooves, inconspicuous nucleoli, and rare intracytoplasmic lumina with no nuclear pseudoinclusions or colloid (Figs. 1A and B). These findings raised the differential of papillary thyroid carcinoma (Fig. 1C), follicular neoplasm (Fig. 1D), medullary carcinoma (Fig. 1E), parathyroid (Fig. 1F), and metastatic breast carcinoma. Immunostaining for GATA-3 (+), ER (+), PAX-8 (-), and TTF-1 (-) was consistent with metastatic breast carcinoma (Fig. 2). We conclude that metastatic breast carcinoma to the thyroid may morphologically mimic primary thyroid carcinoma on FNA; a panel of immunomarkers, such as GATA-3, hormonal marker(s), PAX-8, and TTF-1, may be useful in some cases. GATA-3 immunostaining for metastatic breast carcinoma was helpful in our case and has not been previously reported in a thyroid metastasis sampled by FNA. Diagn. Cytopathol. 2016;44:530-534. © 2016 Wiley Periodicals, Inc.

Comprehensive Immunophenotypic Characterization of Adult and Fetal Testes, the Excretory Duct System, and Testicular and Epididymal Appendages.

The immunophenotype of a normal testis and the excretory duct system has not been studied comprehensively in fetal and adult patients without testicular disease or hormonal manipulation so far. In addition, testicular (TA) and epididymal (EA) appendages are frequent paratesticular structures without previously reported comprehensive immunophenotypic studies. Immunohistochemistry for multiple markers, including the androgen receptor (AR), the estrogen receptor (ER), the progesterone receptor (PR), the prostate-specific antigen, the prostate-specific membrane antigen, PAX8, WT1, calretinin, CK7, CK20, OCT4, SALL4, and CD117, was performed on full sections of testicular/paratesticular tissue from a large cohort of adult and fetal autopsy patients. In contrast to adult germ cells (GC), fetal GC strongly express OCT4 and CD117, although the expression of these proteins is lost in the early postnatal period; SALL4, in contrast, is expressed in both fetal and adult GC, with only weak and focal expression in adult patients. Fetal Sertoli cells (SC) express WT1 and calretinin strongly and diffusely, in contrast to adult SC. Both fetal and adult excretory duct systems express CK7 and PAX8 with frequent AR coexpression, and all 3 main segments of the excretory duct system (ductuli efferentes, epididymis, and vas deferens) have unique immunophenotypes. The rete testis also has a unique immunohistochemical expression pattern, which includes strong expression of CK7, PAX8, WT1, calretinin, and AR. Finally, of the adult autopsy patients examined, 80% had a TA, and 60% had an EA; these paratesticular structures occurred at stereotypical locations, demonstrated reproducible morphologic features, and had a unique immunophenotype relative to other studied structures, with strong CK7, PAX8, WT1, AR, ER, and PR coexpression. The testis and the paratestis may be involved by diverse neoplastic and non-neoplastic processes, and knowledge of the immunophenotypic expression spectrum of these tissues may aid in clinical diagnosis and advance our understanding of the pathogenesis of both oncologic and nononcologic disease processes.

Clinicopathologic characteristics of anterior prostate cancer (APC), including correlation with previous biopsy pathology.

Anterior-predominant prostate cancer (APC) is an incompletely understood entity which can be difficult to sample via transrectal biopsy. Seemingly favorable biopsy results may belie the potential aggressiveness of these tumors. Here, we attempt to characterize APC by retrospectively examining the clinicopathologic features of APC at radical prostatectomy and comparing our findings with prior biopsy information. We found that 17.4 % of patients in our study had APC. APC demonstrated a significantly lower (P value < 0.05) Gleason score (GS) and pathologic stage than non-APC tumors, including the absence of seminal vesicle invasion by APC. A subset (5.6 %) of APC consisted of high-grade tumors (GS ≥ 8), and these tumors were more often detected on transperineal saturation biopsy than non-transperineal saturation (i.e., transrectal ultrasound guided) biopsy strategies. Four patients (7 %) without transperineal saturation biopsy exhibited a significantly worse GS at RP than biopsy, compared to five patients (36 %) with transperineal saturation biopsy. Our findings corroborate the difficulty in detecting APC and suggest that APC is not a uniform disease with a wholly indolent phenotype. Dedicated long-term outcome data are needed in these patients. Additionally, alternative pathologic staging parameters may be necessary.

MiT Family Translocation-Associated Renal Cell Carcinoma: A Contemporary Update With Emphasis on Morphologic, Immunophenotypic, and Molecular Mimics.

Translocation-associated renal cell carcinoma (t-RCC) is a relatively uncommon subtype of renal cell carcinoma characterized by recurrent gene rearrangements involving the TFE3 or TFEB loci. TFE3 and TFEB are members of the microphthalmia transcription factor (MiT) family, which regulates differentiation in melanocytes and osteoclasts, and MiT family gene fusions activate unique molecular programs that can be detected immunohistochemically. Although the overall clinical behavior of t-RCC is variable, emerging molecular data suggest the possibility of targeted approaches to advanced disease. Thus, distinguishing t-RCC from its morphologic, immunophenotypic, and molecular mimics may have important clinical implications. The differential diagnosis for t-RCC includes a variety of common renal neoplasms, particularly those demonstrating clear cell and papillary features; in addition, because of immunophenotypic overlap and/or shared molecular abnormalities (ie, TFE3 gene rearrangement), a distinctive set of nonepithelial renal tumors may also warrant consideration. Directed ancillary testing is an essential aspect to the workup of t-RCC cases and may include a panel of immunohistochemical stains, such as PAX8, pancytokeratins, epithelial membrane antigen, carbonic anhydrase IX, HMB-45, and Melan-A. Dual-color, break-apart fluorescent in situ hybridization for TFE3 or TFEB gene rearrangement may be helpful in diagnostically challenging cases or when molecular confirmation is needed.

Molecular and immunohistochemical characterization reveals novel BRAF mutations in metanephric adenoma.

Metanephric adenoma (MA) is a rare benign renal tumor comprised of a neoplastic proliferation of primitive metanephric tubular cells. A previous study identified BRAF V600E mutations in approximately 90% of MA and found that similar BRAF exon 15 mutations are exceedingly rare in other common renal tumors, including renal cell carcinoma and oncocytoma. A recent follow-up study has validated mutation-specific immunohistochemistry (IHC) for detection of BRAF V600E mutations in a small cohort of MA. Here, we extend these findings to a larger, independent cohort of MA, demonstrating an overall 88% sensitivity and 100% specificity for BRAF V600E IHC. In addition, we report 2 cases of MA with novel BRAF exon 15 mutations, including a V600D missense mutation and a compound V600D and K601L missense mutation. Finally, we evaluate BRAF V600E IHC in a large tissue microarray cohort of common renal tumors and find no significant expression in several renal cell carcinoma subtypes. These data support a role for BRAF V600E IHC in diagnostically challenging cases of MA and expand the spectrum of BRAF exon 15 mutations in this uncommon but unique renal neoplasm.

Many postchemotherapy sarcomatous tumors in patients with testicular germ cell tumors are sarcomatoid yolk sac tumors: a study of 33 cases.

Sarcomatoid neoplasms in patients with testicular germ cell tumors (TGCTs) may show diverse lineages and are usually attributed to "transformation" of teratoma, although origin from yolk sac tumor (YST) has also been suggested. We evaluated 33 sarcomatoid tumors from 23 TGCT patients that lacked specific features of a defined sarcoma subtype for a number of features, including: atypia (mild, moderate, severe), cellularity, tumor necrosis, mitotic index, stromal vascularity, cell profile (spindle or epithelioid), and stromal quality (myxoid and/or fibrous). Immunohistochemical staining analyses directed against cytokeratin (AE1/AE3), SALL4, glypican-3 (GPC3), α-fetoprotein (AFP), p63, glial fibrillary acidic protein (GFAP), CD34, MUC4, smooth muscle actin (SMA), desmin, caldesmon, and myogenin were performed. Staining intensity (0=negative, 1=weak, 2=moderate, 3=strong) and extent (0=<1%, 1=1% to 10%, 2=10% to 50%, 3=>50%) were scored. Tumor grade based on the French sarcoma grading system was assessed, with grades 2-3 considered high grade. Tumors with at least moderate intensity and >10% (+) cells for both AE1/AE3 and GPC3 were considered to be sarcomatoid YST (SYST); 22 tumors from 14 patients (ages 18 to 38 y, mean 27 y) met these criteria and were the focus of this study. All SYSTs occurred after chemotherapy (3 to 132 mo after TGCT diagnosis; mean 42.5 mo, median 30.5 mo). They had spindled (100%; 19 predominant) and epithelioid cells (77%; 3 predominant) in myxoid to fibrous stroma. Thirteen exhibited at least focally severe nuclear atypia. Distinctive tumor "ringlets" and intercellular basement membrane deposits (parietal YST differentiation) were common. In addition to positivity for AE1/AE3 and GPC3, 15/22 were SALL4 (+), 10/22 were at least focally CD34 (+), and 2/22 were focally p63 (+). Fifty percent exhibited smooth muscle differentiation as evidenced by desmin (8/19), caldesmon (2/4), and/or SMA (4/6) reactivity. AFP, MUC4, GFAP, and myogenin were negative in all cases. On follow-up, 8/14 patients died of disease at 7 to 217 months (mean 58 mo) after the initial SYST diagnosis, whereas 5/14 were alive and had no evidence of disease (ANED) at 1 to 259 months (mean 83 mo). One patient died of unrelated causes at 39 months. Of the 11 patients with high-grade tumors, 8 were dead of disease, 1 died of an unrelated cause, and 2 were ANED; all 3 patients with low-grade tumors were ANED at 41 to 262 months (mean 128 mo). We conclude that a high proportion of sarcomatoid tumors in postchemotherapy resections of TGCT patients are SYSTs. These typically occur several years after diagnosis and behave aggressively when high grade.