Human Papillomavirus (HPV) is not involved in urothelial tumorigenesis L. Cheng * , R. Alexander, A. Lopez-Beltran * Indiana University, Dept. of Pathology, Indianapolis, USA Objective: The purposes of this study were to investigate the possible role of human papillomavirus in the development of squamous cell carcinoma of the urinary bladder and to determine if p16 expression could serve as a surrogate marker for human papillomavirus in this malignancy. Method: Forty-two cases of squamous cell carcinoma of the urinary bladder and 27 cases of urothelial carcinoma with squamous differentiation were investigated. HPV infection was analyzed by both in situ hybridization at the DNA level and immunohistochemistry at the protein level. p16 protein expression was analyzed by immunohistochemistry. Results: Human papillomavirus DNA and protein were not detected in 42 cases of squamous cell carcinoma (0 %, 0/42) or 27 cases of urothelial carcinoma with squamous differentiation (0 %, 0/15). p16 expression was detected in ten cases (31 %, 13/42) of squamous cell carcinoma and nine cases (33 %, 9/27) Method: A review of clinical data from an ADPKD patient with TCC admitted in our hospital and a review of current literature regarding ADPKD and TCC were made. Results: The patient is a 77 year-old woman with chronic renal failure due to ADPKD, on hemodialysis for 2 years. She was admitted with left lumbar pain, hematuria and fever. Radiological exams revealed various complex cysts with dense material that did not enhance with contrast, compatible with hematic cysts in the context of ADPKD. The whole clinical findings suggested cystic infection complicated with sepsis, so nefrectomy was performed. Macroscopic examination of the ressected kidney revealed a white granulous nodular formation with 4.5 cm diameter in the renal pelvis. Histological examination confirmed a highgrade papillary TCC with parenchymal infiltration (pT3) and extense scamous differentiation. Conclusion: The present case illustrates that TCC can occur in ADPKD, despite its rarity. It can be difficult to successfully diagnose TCC on ADPKD based on clinical-radiological findings. Objective: Carcinoid tumor is a very uncommon neoplasm in the kidney. We report the histopathologic and immunohistochemical (IHQ) study of two new cases. Method: Case 1: 48 year-old female with a 4 cm asymptom-atic¨cystic¨mass discovered in a routine exam. The patient underwent tumorectomy. Case 2: 77 year-old female with a 3 cm renal mass who underwent left nephrectomy. Two months later a needle biopsy confirmed carcinoid tumor metastasis in the liver. Both patients currently free of disease. Results: Both tumors showed similar histologic features. Neoplastic cells were grouped in nests, ribbons, and pseudoglands with rosette-like appearance and showed eosinophilic granular cytoplasm and chromatic nuclei. Low mitotic index. IHC: diffuse/intense cytoplasmic staining for CD56, CD57, AE1/AE3, chromogranin and synaptophysin. Conclusion: Primary renal carcinoid tumor is rare in the clinical practice. The histological findings correspond to a well differentiated neoplasm and are similar to carcinoid tumors in other locations, which makes the diagnosis feasible even without previous personal experience. IHC confirms the diagnosis. It usually behaves as a low grade neoplasm, but recurrences and metastases do occur. Only single cases and short series have been published so far. There is no accumulated experience to establish long term prognosis.