Purpose To analyze the clinicopathologic and immunohistochemical features, differential diagnosis and prognosis of papil-lary renal cell carcinoma (PRCC). Methods Thirty-two cases of PRCC diagnosed were reviewed. A retrospective study was per-formed including reviewing the clinical documents, pathological sections and immunohistochemical stainning and follow-up was made of 32 cases of PRCC. Twenty-one patients were treated with radical nephrectomy, eleven patients were treated with partial nephrectomy. Results Among 770 cases of renal epithelial tumors 32(4. 2%) cases of PRCC were detected. Histologically, the PRCC were charac-terized by varying proportions of papillary and tubular architecture covered by single or multiple layer of tumor cells with scanty or volu-minous basophilic or eosinophilic cytoplasm. Foam cells and psammoma bodies were seen in some papillary cores and stroma, and the cytoplasm of some tumor cells contained hemosiderin. Of these 32 patients, 18 and 14 were diagnosed type-Ⅰand type-IIPRCC, re-spectively. Type-I, with small cuboid cell and pale cytoplasm, 16 of them were low in Fuhrman grading, Type-II, with large colunmar cells, rich in eosinophilic cytoplasm, 12 of them were high in Fuhrman grading. Immunohistochemically, the PRCC showed positive immunostaining for vimentin, EMA, CK(AE1/AE3), CK7, CD10 and AMACR. All the tumors studied were negative for CK (34βE12) and TFE-3. Follow-up data were available for 31 cases, 4 patients died of cancer specific causes, 1 with type-Ⅰand 3 with type-II tumors after surgery. The other 27 patients were alive without recurrence or metastasis. High Fuhrman grading, intravascular tumor emboli, lymph node metastasis and high clinical stage were prognostic indicators in PRCC. Conclusions PRCC with unique pathological features is not a common subtype of renal cell carcinoma in China. The presence of higher nuclear grade, sarcomatoid ele-ments or clear cell carcinoma structure may indicate an aggressive biologic behavior and poor prognosis. Close attention to the cytologic and growth pattern characteristics will allow us to arrive at the proper diagnosis in most cases, although sometimes immunohistochemis-try and rarely molecular genetic evaluation may be needed.

OBJECTIVETo explore the significance of multi-detector CT (MDCT) in differential diagnosis of papillary renal cell carcinoma and chromophobe renal cell carcinoma.

METHODSClinical data of forty-one cases of renal cancers confirmed pathologically were collected, including 21 cases of papillary renal cell carcinoma (PRCC) (14 type I, 7 type II) and 20 cases of chromophobe renal cell carcinoma (ChRCC). Their morphological and MDCT characteristics were retrospectively analyzed. Receiver operator characteristic curve (ROC) was used to analyze the value of MDCT in differential diagnosis of PRCC and ChRCC. Two senior radiologists analyzed the morphological and the dynamic enhancement characteristics of the images. The attenuation of the lesions and the adjacent renal parenchyma were measured. The morphological indexes were compared with chi-square test and the quantitative indexes were compared with independent sample T-test. Receiver operator characteristic curve (ROC) was used to analyze the sensitivity, specificity and accuracy of diagnosis of PRCC and ChRCC.

RESULTSAngioid enhancement and filled enhancement were more common in ChRCC than in PRCC, while delayed enhancement was more often seen in PRCC than in ChRCC. Calcification was more common in type I than type II PRCC. The enhancement value (ΔCT value) in corticomedullary phase was (29.08 ± 20.12) Hu for PRCC, significantly lower than the (48.29 ± 26.70) Hu for ChRCC (t = -2.611, P = 0.013). The ΔCT value of type I PRCC in corticomedullary phase was (26.36 ± 18.16) Hu, showing a significant difference from that of ChRCC (t = -2.666, P = 0.012). The lesion to kidney ratio (LKR) in corticomedullary phase was 0.44 ± 0.19 for PRCC and 0.58 ± 0.15 for ChRCC, with a significant difference between them (t = -2.587, P = 0.014). The LKR of type I PRCC in corticomedullary phase was 0.39 ± 0.15, showing a significant difference from that of ChRCC (t = -3.628, P = 0.001). The difference value (D-value) of the attenuation of lesion between corticomedullary and nephrographic phases was (-3.69 ± 8.90) Hu for PRCC and (8.39 ± 21.98) Hu for ChRCC, with a significant difference between them (t = -2.285, P = 0.031). The D-value of type I PRCC was (-4.55 ± 9.82) Hu, showing a significant difference from that of ChRCC (t = -2.323, P = 0.028). There was no significant difference between the ΔCT, LKR and D-value of the type II PRCC and ChRCC (P > 0.05 for all). The area under the curve (AUC) for ΔCT value, LKR value in corticomedullary phase, and D-value were 0.718, 0.751 and 0.668, respectively, and there were no significant differences among them (z values were 0.896, 0.683 and 0.559, respectively, and P values were 0.370, 0.495 and 0.576, respectively). Using 49.350 Hu as the cutoff value for ΔCT value in corticomedullary phase, resulted in a sensitivity, specificity and accuracy of 50.0%, 90.5% and 70.7%, respectively. Corresponding values were 65.0%, 81.0% and 73.2%, when using a cutoff value of 0.532 for LKR in corticomedullary phase, and were 60.0%, 76.2% and 68.3%, when using a D-value of 0.400 Hu.

CONCLUSIONSThe ΔCT value, LKR value in corticomedullary phase, and the D-value are all useful indexes for the differentiation of PRCC and ChRCC.

Area Under Curve ; Calcinosis ; Carcinoma, Renal Cell ; diagnosis ; Diagnosis, Differential ; Humans ; Kidney ; Kidney Neoplasms ; diagnosis ; ROC Curve ; Retrospective Studies ; Sensitivity and Specificity