Clinicopathological study of pheochromocytoma of the urinary bladder: immunohistochemical, flow cytometric and ultrastructural findings with review of the literature.

Pheochromocytomas usually arise from the adrenal medulla but may also arise from the carotid body, the retroperitoneum, the urinary bladder, and other locations. We report three cases of pheochromocytoma of the urinary bladder with clinicopathological, immunohistochemical, flow cytometric, and ultrastructural findings. Case 1, a 13-year-old boy presented with hematuria. He underwent partial cystectomy, 31 years later he presented with a tumor in the thoracic vertebra. Case 2, a 35-year-old woman presented with headache, nausea, vomiting, palpitations, and diaphoresis on evacuation. She underwent total cystectomy and regional lymph adenectomy. She survived for 10 years without recurrence or metastasis; however, she died from another disease. Case 3, a 31-year-old man presented with dysuria. He underwent total cystectomy and regional lymph adenectomy. The tumor metastasized to the lymph nodes, and the patient died after 4 years. The urinary bladder tumors in these three cases protruded into the lumen and invaded deeper than the middle of the muscle layer. The tumor of the urinary bladder, metastatic lymph nodes, and thoracic vertebra showed alveolar and trabecular patterns, and tumor cells were surrounded by capillaries. The tumor cells were moderate in size with ovoid nuclei and abundant eosinophilic cytoplasm that contained acidophilic granules reactive to Grimelius stain. Vascular invasion was observed in cases 1 and 2. Immunohistochemically, tumor cells showed reactivity for chromogranin, Leu 7, and S-100 protein. In each of the three cases, the DNA ploidy pattern on flow cytometry was aneuploid. Ultrastructural examination revealed several neurosecretory granules, rough endoplasmic reticulum, and a few mitochondria within the cytoplasm. It is difficult to determine whether pheochromocytoma of the urinary bladder is malignant on the basis of histological, immunohistochemical, and flow cytometric findings. Long-term follow up is necessary.