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Nested variant of urothelial carcinoma (NVUC) is a rare and often unrecognized urothelial neoplasia. Diagnosis is based on morphology only, and no immunohistochemical or cytogenetic differences from usual high-grade urothelial carcinomas have been reported.We describe the case of a 49-year-old woman affected by hepatitis C virus presented with fever, discomfort, urgency, and hypertension. Computed tomography showed a sclerosing inflammatory process involving the connective and adipose tissue of the renal sinus. In the absence of renal or pelvic masses an underlying malignancy was excluded and renal abscess or tuberculosis was suspected. Accordingly, nephrectomy and proximal ureterectomy was performed. Grossly, calices, renal pelvis, and pyeloureteral junction appeared modestly dilated with whitish, thickened, and uneven mucosa. Microscopically, the subepithelial connective tissue, the fibromuscular layer, and the renal sinus fat were diffusely infiltrated by small nests of medium to large urothelial cells (p63 positive) with abundant eosinophylic cytoplasm and slightly atypical nuclei.On the basis of morphologic and immunohistochemical features, a diagnosis of NVUC was made. After surgery, the patient recovered from hypertension. Pelvic and upper urothelial tract NVUCs are uncommon, and to the best of our knowledge, this is the second case of NVUC with renal involvement.

Background T-cell lymphoblastic lymphoma comprises approximately 85-90% of all lymphoblastic lymphomas. It often arises as a mediastinal mass, and with bone marrow involvement. Presentation at other sites without nodal or mediastinal localization is uncommon. Case report We describe clinical, histologic, immunohistochemical, and molecular features of two cases of primary T-cell lymphoblastic lymphoma arising respectively in uterine corpus and testis. The tumors were composed by medium to large cells, exhibiting a diffuse pattern of growth but sometimes forming indian files or pseudo-rosettes. The neoplastic cells strongly expressed TdT and T-cell markers in both uterine corpus and testis. However, the testis case also showed aberrant expression of B-cell markers, thus molecular biology was necessary to achieve a final diagnosis. T-cell receptor gene rearrangement analysis identified a T-cell origin. Conclusions To the best of our knowledge, only one doubtful previous case of primary uterine T-cell lymphoblastic lymphoma and no previous cases of primary testicular T-cell lymphoblastic lymphoma have been reported. Due to the morphology of neoplastic cells, a challenging differential diagnosis with all the tumors belonging to the so-called small round blue cell tumor category is mandatory. In ambiguous lineage cases, molecular biology may represent an adequate tool to confirm diagnosis. Virtual Slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1559880973128230