Background: Most histopathological variants of renal cell carcinomas (RCC) are showing distinct morphological patterns. However, there are some overlaps between some variants, which in turn, affect the prognosis. The aim of this review articleis to distinguish the recently described variants of RCCs and to illustrate the role of immunohistochemistry and genetic study in diagnosis of confusing cases. Conclusions: Applying immunohistochemical and moleculartests in addition to routine staining allow better classification of different variants of RCCs.

Background and aim: Chemokine receptor (CXCR)4 is a G-protein coupled receptor involved in many biological processes as inflammation, angiogenesis and immune responses. Previous researches illustrated that CXCR4 expression has been detected in many carcinomas of various origins. The aim of this study was to evaluate the possible prognostic value of CXCR4 in RCCs by correlating immunohistochemical expression of CXCR4 with different patients' clinical and pathological criteria. Methods: Formalin-fixed paraffin embedded tissue blocks of 49 specimens of RCCs were evaluated for CXCR4 expression by immunohistochemistry (IHC). Correlation of CXCR4 expression with different clinical and pathological data was measured statistically. Results: Nuclear expression of CXCR4 was correlated to International society of urological pathology (ISUP) grading system that is applied for ccRCCs and papillary RCCs (p=0.024). Both cytoplasmic and membranous expression of CXCR4 were associated with histological subtypes of the studied RCC cases (p<0.0001) and Fuhrman nuclear grading system (p=0.008 &p<0.0001). Membranous CXCR4 was inversely correlated to pathological T stage of the studied RCCs (p=0.035). Conclusions: Expression of CXCR4 decreases in advanced stages of RCC. CXCR4 is a valuable prognostic biomarker in RCCs and should be evaluated in each subcellular localization.