Endocrine Abstracts

Bladder Paragangliomas (PGLs) are a rare manifestation of sympathetic chain PGLs and occur in prone patients with SDH mutation.They often display an aggressive phenotype with metastatic disease and require long-term follow up. SDHB immunostaining plays a significant role in initial risk stratification and facilitating appropriate genetic testing. We report four cases illustrating diagnostic management and outcome issues in this rare neuroendocrine pathology; two with SDHB mutation, 1 SDHA and 1 awaiting extended genetic analysis in view of young age (33 years).We anticipate a positive SDH mutation due to the anatomical location and pathogenicity. Our patients ranged from 29 to 67 years of age (median 42 years), 2M and 2F with predominant presentation being haematuria. Headache and sympathetic symptoms during micturition were also present in two patients. Plasma normetadrenaline was elevated in three patients and urine dopamine was also elevated in one who tested positive for SDHB mutation and subsequently developed metastatic disease. Initial biochemistry was not available in one patient as he underwent tumour resection in another centre several years ago. The tumours in all four patients displayed MIBG avidity although they are reported to have preference for FDG-PET and Gallium Dotatate. SDHB immunostaining is currently available in one patient only (67 year old lady) who tested negative in our initial routine genetic panel. However, she underwent screening for SDHA as the tumour sample repeatedly stained negative on SDHB immunohistochemistry indicating a likely mutation. SDHA frameshift variant Exon 2 c.133_136delinsCCT was identified which has not been previously reported in bladder PGLs. We conclude that SDHB immunostaining still remains an indispensable tool especially for the evaluation of bladder Paraganglioma. As new causative genes become validated, extended genetic panel should be included in screening bladder PGLs especially mutations involving all SDH and other genes involved in the regulation of citric acid cycle.