Perivascular epithelioid cell tumor (PEComa) of the urinary bladder is an exceptionally rare mesenchymal neoplasm and may be difficult to diagnose preoperatively. We report a rare case of a hypervascular bladder PEComa with TFE3 expression in an adolescent female that was clinically misdiagnosed as paraganglioma. A 16-year-old girl presented with intermittent gross hematuria. Imaging revealed a hypervascular submucosal bladder mass with marked homogeneous enhancement on computed tomography urography (CTU) and mild-to-moderate uptake on somatostatin receptor imaging, leading to suspicion of paraganglioma and preoperative α-adrenergic blockade. Histopathologic examination after transurethral resection showed epithelioid tumor cells with a low proliferative index. Immunohistochemistry demonstrated nuclear TFE3 positivity and strong cathepsin K expression, while melanocytic and neuroendocrine markers were negative, supporting a diagnosis of PEComa showing TFE3 immunoreactivity. The patient remains disease-free at six months of follow-up. This case highlights an important diagnostic pitfall of hypervascular bladder tumors mimicking paraganglioma, particularly in adolescent patients.
Ou et al. (Wed,) studied this question.