Context.-Because of the limited number of available primary bladder paraganglioma (PBPG) cases, the rates of succinate dehydrogenase (SDH) mutations and the clinicopathologic characteristics of SDH-deficient tumors have not been fully studied.Objective.-To define the clinicopathologic and molecular characteristics of PBPGs.Design.-A total of 52 PBPGs were collected retrospectively. SDHA and SDHB immunohistochemical stains were performed. In cases of SDHB expression loss, mutation analyses of SDHB, SDHC, and SDHD were performed.Results.-The clinicopathologic features were analyzed for 52 cases (M:F ¼ 27:25), with a mean age of 56 years (range, 22-79 years). Tumor sizes were 0.5 to 8 cm (mean, 2.4 cm). Tumor necrosis was present in 5 of 52 cases (10%), involvement of muscularis propria in 41 (79%), and lymphovascular tumor invasion in 6 (12%). During a mean follow-up period of 41 months (range, 1-161 months), 3 of 52 patients (6%) developed metastases, but no one died from the disease. Immunohistochemistry for SDHA and SDHB showed that all cases were SDHA intact. Among them, 43 cases had intact SDHB, whereas 9 cases were SDHB deficient. Compared with the SDHB-intact cases, the SDHB-deficient cases were characterized by large tumor sizes (4.5 versus 1.9 cm; P , .001), a higher number of mitoses per 10 high-powered fields (2.6 versus 0.1; P ¼ .002), and frequent lymphovascular tumor invasion (33% versus 7%; P ¼ .02) and metastases (22% versus 2%; P ¼ .02). Mutational analyses for SDHB, SDHC, and SDHD were performed in 9 SDHB-deficient cases. Among them, 6 cases were successfully sequenced and revealed SDHB mutations only.Conclusions.-Large tumor size, a higher number of mitoses, and the presence of lymphovascular tumor invasion and SDHB mutations suggest malignant paraganglioma.

BackgroundHistologic grade is the most important predictor of the clinical outcome of non-muscle invasive (Ta, T1) papillary urothelial carcinoma (NMIPUCa), but its ambiguous criteria diminish its power to predict recurrence/progression for individual patients. We attempted to find an objective and reproducible histologic predictor of NMIPUCa that correlates well with the clinical outcome.MethodsA total of 296 PUCas were collected from the Departments of Surgical Pathology of 11 institutions in South Korea. The clinical outcome was grouped into no event (NE), recurrence (R), and progression (P) categories. All 25 histological parameters were numerically redefined. The clinical pathology of each case was reviewed individually by 11 pathologists from 11 institutions based on the 2004 WHO criteria and afterwards blindly evaluated by two participants, based on our proposed parameters. Univariate and multivariate logistic regression analyses were performed using the R software package.ResultsThe level of mitoses was the most reliable parameter for predicting the clinical outcome. We propose a four-tiered grading system based on mitotic count (> 10/10 high-power fields), nuclear pleomorphism (smallest-to-largest ratio of tumor nuclei >20), presence of divergent histology, and capillary proliferation (> 20 capillary lumina per papillary core).ConclusionsThe level of mitoses at the initial bladder biopsy and transurethral resection (TUR) specimen appeared to be an independent predictor of the Ta PUCa outcome. Other parameters include the number of mitoses, nuclear pleomorphism, divergent histology, and capillary proliferation within the fibrovascular core. These findings may improve selection of patients for a therapeutic strategy as compared to previous grading systems.Electronic supplementary materialThe online version of this article (doi:10.1186/s13000-017-0639-y) contains supplementary material, which is available to authorized users.