Glandular lesions of the urinary bladder: clinical significance and differential diagnosis

A variety of glandular or pseudoglandular lesions may be seen in the urinary bladder, ranging from those that are entirely benign to aggressive-behaving malignant primary and secondary tumours. Lesions with minimal to no evident premalignant potential include several proliferative and reactive processes, such as cystitis cystica and cystitis glandularis, although the possibility exists for confusion of such lesions with an infiltrative neoplasm, particularly in limited biopsy specimens. Similarly, ectopic tissues of Mullerian origin may be seen occasionally in the urinary bladder and their differentiation from a true glandular neoplasm is important to avoid improper treatment. As urothelial carcinoma has a propensity for divergent differentiation, a wide spectrum of morphological variants exists with varying degrees of glandular differentiation. Some such variants have demonstrated clinical behaviour that is more aggressive than their histology would suggest, thus deserving recognition and potentially different treatment. In this paper, we review the glandular lesions of the urinary bladder ranging from benign proliferative processes to malignant primary and secondary neoplasms, with emphasis on clinical significance and features useful in resolving their differential diagnoses.