Differentiation of inverted papilloma from inverted-pattern carcinoma

Differentiating urothelial carcinoma with an inverted (endophytic) growth pattern from benign inverted papilloma can be problematic, especially in biopsy or transurethral resection specimens.

			Inverted papilloma	Inverted-pattern urothelial carcinoma
	Cytological atypia		0/151	29/291
	Exophytic component		0/151	22/291
	Coexisting flat urothelial dysplasia / CIS		0/151	0/291
	Stromal invasion		0/151	12/291
	Peripheral palisading		15/151	13/291
	Mitotic activity	<1/10HPF	12/151	5/291
		1 to 5/10HPF	3/15( 2 cases 1/10HPF, 1 case 2/10HPF)1	16/29(mean 8/10HPF)1
		>5/10HPF	0/151	8/291
	Ki-67		0/151, 0/102	19/291
	p53		1/151, 1/102	17/291
	CK20		0/151, 0/102	17/291
	Positive for Ki-67 or p53 or CK20		1/151	26/291
	UroVysion FISH positivity		0/151	21/291
	Positive for Ki-67 or p53 or CK20 or UroVysion FISH		1/151	29/291

References

1 Jones TD, Zhang S, Lopez-Beltran A, et al. Urothelial carcinoma with an inverted growth pattern can be distinguished from inverted papilloma by fluorescence in situ hybridization, immunohistochemistry, and morphologic analysis. Am J Surg Pathol 2007; 31:1861-7

2 Broussard JN, Tan PH,Epstein JI. Atypia in inverted urothelial papillomas: pathology and prognostic significance. Hum Pathol 2004; 35:1499-504

This page last revised 2.3.2008.

©SMUHT/PW Bishop