Course Map: Epithelial Tumors: Benign: Urothelial Papilloma

Urothelial Papilloma
These tumors have a delicate fibrovascular core and are lined by urothelium. The latter resembles that of a normal, contracted bladder in thickness (approximately half dozen cell layers) and cellular features. There may be branching of the fronds, but there should not be fusion of adjacent fronds. Umbrella cells are usually prominent, but mitoses are absent or rare. These lesions are rare, quite small usually and most occur in younger patients (under age 50) [44].
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	Figure 1: A typical papilloma. The frond in the lower center field has some edema, but small blood vessels are evident.
	Figure 2: Papilloma with branching.
	Figure 3: The superficial umbrella cells are not conspicuous in this papilloma.
	Figure 4: The superficial umbrella cells are uncommonly prominent in this papilloma.