Urinary bladder. Mimics of neoplasia and new pathologic entities.

A wide range of epithelial and mesenchymal pseudoneoplastic disorders of the urinary bladder may clinically and pathologically mimic a malignant neoplasm. These lesions usually require a tissue biopsy for definitive diagnosis. It is important to be aware of these lesions and their spectrum of morphologic appearances to avoid overdiagnosis and inappropriate aggressive therapy.