Inverted urothelial papillomas with foamy or vacuolated cytoplasm

Fine, Samson W.; Epstein, Jonathan I.

doi:10.1016/j.humpath.2006.05.014

Cited by 21 publications

(15 citation statements)

References 26 publications

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“…11 One study reported that IUPs with focal atypia do not tend to recur or be seen in association with 11 However, many reported cases of "atypical IUP" in the literature are described with an exophytic papillary component and significant atypia and/or mitoses, which would best be considered UC with inverted growth. 8,17 IUP with a focal papillary pattern has also been described. 24 The papillary component in these cases should be focal and histologically similar to a urothelial papilloma with benign appearing urothelium of normal thickness and no cytologic atypia or mitoses.…”

Section: Morphology and Variantsmentioning

confidence: 95%

“…16 On cystoscopy, IUP appears as a pedunculated mass or polypoid/papillary tumour with a smooth surface. 11,17 Magnetic resonance imaging (MRI) typically shows a polypoid lesion with a non-papillary surface, a thin short stalk, and occasional cystic foci. 10 IUP tends to be isointense on T1-weighted images and either isointense or slightly higher in intensity than the wall of the bladder on T2-weighted images.…”

Section: Imagingmentioning

confidence: 99%

“…9,12 Studies have shown rates of IUP recurrence from 1-7%, which occur 5-30 months following resection. 1,[3][4][5][6][7]12,16,17 Furthermore, incomplete tumour resection contributes to a higher recurrence rate. 7,9 However, as there are no reported cases of metastases arising from an IUP, it is believed that this lesion does not have malignant potential.…”

Section: Biological Behaviourmentioning

confidence: 99%

“…IUP should lack any significant exophytic component or fibrovascular cores and should be non-invasive, showing no desmoplasia, stromal inflammation, or involvement of the muscularis propria. 17 IUPs are typically trabecular lesions composed of anastomosing cords of urothelial cells with nuclear streaming and peripheral palisading of basal nuclei. 21 A glandular variant was proposed that had pseudoglandular and/or true glandular spaces with mucus-containing goblet cells.…”

Section: Morphology and Variantsmentioning

confidence: 99%

“…28 CK7 positivity can be seen in IUP, especially in cases with vacuolated cells. 17 Moreover, CK7 positivity and the absence of staining for PAS, PAS-D, and mucicarmine favours a diagnosis of IUP with vacuolated cells over the clear cell variant of UC. 17 IUP has a molecular profile distinct from UC.…”

Section: Distinguishing Iup From Ucmentioning

confidence: 99%

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Inverted urothelial papilloma: A review of diagnostic pitfalls and clinical management

Sweeney

Rais‐Bahrami

Gordetsky

2017

CUAJ

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Inverted urothelial papilloma (IUP) is a rare, non-invasive endophytic lesion that accounts for 1-2% of urothelial tumours. On cystoscopy, IUP appears as a pedunculated/papillary mass with a smooth surface. On microscopy, IUP has an endophytic growth pattern with the bulk of the tumour covered by a superficial layer of urothelium, which can be hyperplastic or attenuated. The cytology should be bland, with uniform, spindled cells arranged in anastomosing trabeculae and cords with peripheral palisading of basaloid cells. Exophytic papillae and mitotic activity should be absent or focal. Pseudoglandular spaces and squamous metaplasia may also be present. There are distinct molecular differences between IUP and urothelial carcinoma (UC). IUP rarely has mutations of FGFR3, homozygous loss of 9p21, or gain of chromosomes 3, 7, and 17, whereas these mutations are frequently seen in UC. In addition, IUP is much less likely to have TERT mutations compared to UC. Immunohistochemistry can also be helpful in distinguishing the two entities as IUP is typically negative for CK20 and has a low Ki-67 proliferation index. Positivity for p53 may be seen in a minority of IUP. IUP can recur and be seen in association with UC.Distinguishing IUP from UC can be difficult due to the similarity between the two entities both on cystoscopy and histology, as up to 25% of UCs will also have inverted growth. Given the morphologic variants of IUP and UC, it is possible for a diagnostic error to occur, which can significantly impact patient management.

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