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The International Society of Urological Pathology held a conference devoted to issues in testicular and penile pathology in Boston in March 2015, which included a presentation and discussion led by the testis microscopic features working group. This conference focused on controversies related to staging and reporting of testicular tumors and was preceded by an online survey of International Society of Urological Pathology members. The survey results were used to initiate discussions, but decisions were made by expert consensus rather than voting. A number of recommendations emerged from the conference, including that lymphovascular invasion should always be reported and no distinction need be made between lymphatic or blood invasion. If lymphovascular invasion is equivocal, then it should be regarded as negative to avoid triggering unnecessary therapy. Lymphovascular invasion in the spermatic cord is considered as category pT2, not pT3 unless future studies provide contrary evidence. At the time of gross dissection, a block should be taken just superior to the epididymis to define the base of the spermatic cord and direct invasion of tumor in this block indicates a category of pT3. Pagetoid involvement of the rete testis epithelium must be distinguished from rete testis stromal invasion, with only the latter being prognostically useful. Percentages of different tumor elements in mixed germ cell tumors should be reported. Although consensus was reached on many issues, there are still areas of practice that need further evidence on which to base firm recommendations.

The International Society of Urological Pathology held a conference devoted to issues in testicular and penile pathology in Boston in March 2015, which included a presentation and discussion led by the testis microscopic features working group. This conference focused on controversies related to staging and reporting of testicular tumors and was preceded by an online survey of the International Society of Urological Pathology members. The survey results were used to initiate discussions, but decisions were made by expert consensus rather than voting. A number of recommendations emerged from the conference, including that lymphovascular invasion (LVI) should always be reported and no distinction need be made between lymphatic or blood invasion. If LVI is equivocal, then it should be regarded as negative to avoid triggering unnecessary therapy. LVI in the spermatic cord is considered as category pT2, not pT3, unless future studies provide contrary evidence. At the time of gross dissection, a block should be taken just superior to the epididymis to define the base of the spermatic cord, and direct invasion of tumor in this block indicates a category of pT3. Pagetoid involvement of the rete testis epithelium must be distinguished from rete testis stromal invasion, with only the latter being prognostically useful. Percentages of different tumor elements in mixed germ cell tumors should be reported. Although consensus was reached on many issues, there are still areas of practice that need further evidence on which to base firm recommendations.

Renal Medullary Carcinomas (RMCs) and Collecting Duct Carcinomas (CDCs) are rare subsets of lethal high-stage, high-grade distal nephron-related adenocarcinomas with a predilection for the renal medullary region. Recent findings have established an emerging group of fumarate hydratase (FH)-deficient tumors related to hereditary leiomyomatosis and renal cell carcinoma syndrome (HLRCC-RCCs) within this morphologic spectrum. Recently-developed, reliable ancillary testing has enabled consistent separation between these tumor types. Here, we present the clinicopathologic features and differences in the morphological patterns between RMCs, CDCs and FH-deficient RCCs in consequence of these recent developments. This study included a total of 100 cases classified using contemporary criteria and ancillary tests. Thirty-three RMCs (SMARCB1/INI1-deficient, hemoglobinopathy), 38 CDCs (SMARCB1/INI1-retained) and 29 RCCs defined by the FH-deficient phenotype (FH-/2SC+ or FH±/2SC+ with FH mutation, regardless of HLRCC syndromic stigmata/ history) were selected. The spectrum of morphologic patterns was critically evaluated and the differences between the morphological patterns present in the three groups were analyzed statistically. Twenty five percent of cases initially diagnosed as CDC were reclassified as FH-deficient RCC based on our contemporary diagnostic approach. Among the different overlapping morphologic patterns, sieve-like/cribriform and reticular/yolk sac tumor-like patterns favored RMCs, whereas intracystic papillary and tubulocystic patterns favored FH-deficient RCC. Tubulopapillary pattern favored both CDCs and FH-deficient RCCs, and multinodular infiltrating papillary pattern favored CDCs. Infiltrating glandular and solid sheets/cords/nested patterns were not statistically different among the three groups. Viral inclusion-like large nucleoli considered as a hallmark of HLRCC-RCCs were observed significantly more frequently in FH-deficient RCCs. Despite the overlapping morphology found among these clinically aggressive infiltrating high-grade adenocarcinomas of the kidney, reproducible differences in morphology emerged between these categories after rigorous characterization. Finally, we recommend that definitive diagnosis of CDC should only be made if RMC and FH-deficient RCC are excluded.

Aims: In some cases distinction between chromophobe renal cell carcinoma (CRCC), oncocytoma and clear cell (conventional) renal cell carcinoma (eosinophilic variant) using routine light microscopy remains problematic. The present study investigates the level of agreement in the diagnosis of CRCC, as well as the histological features most frequently used for this diagnosis by two pathologists with a special interest in renal neoplasia. The sensitivity and specificity of immunohistochemical markers in cases with overlapping histological features in the diagnosis of CRCC were also studied. Electron microscopy was performed, as a diagnostic gold standard, on all of the cases. Methods and results: Thirty-two renal tumours with predominantly eosinophilic cytoplasm were reviewed in a blinded fashion by two pathologists. The diagnosis and morphological features used to render each diagnosis were tabulated. Validation of the utility of keratin 7 and 20, epithelial membrane antigen (EMA), vimentin, CD10, parvalbumin, RCC antigen, antimitochondrial antibody and Hale's colloidal iron was performed by the construction of a tissue microarray (TMA) master block. Based on histological criteria alone, overall agreement on the diagnosis of these tumours was reached in 69% of the cases, while there was total disagreement in 12%. In 59% of the cases, total agreement was reached in classifying the case as a CRCC based on histology alone. Kappa statistics for interobserver variability were calculated as only slight agreement (kappa = 0.3). The histological features most frequently associated with a diagnosis of CRCC were accentuated cell borders (87%) and a combination of hyperchromatic wrinkled nuclei (79%) and perinuclear halos (74%). The most sensitive and specific marker for CRCC was parvalbumin (sensitivity 0.91; specificity 1.0). The immunohistochemical profile of EMA+/ vimentin- was useful but had low specificity (sensitivity 0.75; specificity 0.4). CD10 had the highest sensitivity (1.0) but worst specificity (0.25) for CRCC. Keratin 7 had high sensitivity (0.83) but fairly low specificity (0.37) for CRCC. Hale's colloidal iron and the RCC antigen marker were not contributory. Finally, the antimitochondrial antibody was found to be fairly sensitive (0.83) for excluding CRCC. Conclusions: A small but significant proportion of renal tumours with cells having eosinophilic cytoplasm cannot be classified, even by experienced pathologists, based on histology alone. In these cases it is imperative to use markers with known sensitivity and specificity for the diagnosis of CRCC. ZR 0 Z8 1 ZS 1 ZB 48