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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.

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