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Paraganglioma of the Urinary Bladder Metastatic to the Lung in a Patient with SDHB Gene Mutation: A Case Report


 
 
 Paragangliomas are tumors originating from the neural crest. Most tumors are benign and arise from various locations in the body. Extra-adrenal paragangliomas arise as sporadic cases in most settings or as part of heredofamilial syndromes in about one-quarter of cases. Succinate dehydrogenase subunit B (SDHB) gene mutations are associated with an aggressive clinical disease course of pheochromocytoma/paraganglioma.
 
 
 
 We present a 41-year-old male former smoker with a history of a growing right upper lung nodule on chest imaging. He had no cough or respiratory symptoms. Twenty-seven months prior the patient underwent a cystoprostatectomy due to paraganglioma of the bladder. Genetic testing identified a pathogenic mutation in SDHB gene, c.166_170delCCTCA (p.Pro56Tyrfs*5). He underwent a wedge resection of the lung nodule.
 
 
 
 Sectioning of the lung wedge revealed a well circumscribed, firm tan nodule. Microscopically there were nests of large neoplastic cells with round nuclei and eosinophilic granular cytoplasm. Tumor cells were positive for synaptophysin and chromogranin and negative for pan-cytokeratin. S100 highlighted sustentacular cells. The pulmonary neoplasm was morphologically similar to the prior tumor of the bladder. These features are consistent with a metastatic urothelial paraganglioma to the lung, in a background of a hereditary paraganglioma syndrome.
 
 
 
 Extra-adrenal paraganglioma occurring in a setting of hereditary paraganglioma syndrome has a higher risk of metastasis. Lifelong surveillance even after prompt resection of primary tumor with negative margins is required to ensure early detection of metastasis and prevention of complications associated with it.
