This category includes urothelial papilloma
, papillary urothelial neoplasm of low malignant potential, and low- and high-grade papillary urothelial carcinoma.
The 1973 World Health Organization and 2004 World Health Organization/International Society of Urological Pathology consensus classifications 1973 WHO grading system Urothelial papilloma
Grade 1: Well differentiated Grade 2: Moderately differentiated Grade 3: Poorly differentiated 2004/2016 WHO grading system Urothelial papilloma
(papillary lesions) (completely benign lesion) PUNLMP Low-grade papillary UC High-grade papillary UC PUNLMP; papillary urothelial neoplasm of low malignant potential; UC: urothelial carcinoma; WHO: World Health Organization TABLE 3.
was observed in 2 patients and a total of 12 patients were younger than 15 years, of whom 7 were younger than 10 (6).
(11,21) The youngest patient was a 12 year-old boy with urothelial papilloma
. However, urothelial neoplasms in patients aged younger than 20 years are generally rare.
In 1973, the World Health Organization (WHO) classified bladder tumours based on the degree of cellular differentiation, as either urothelial papilloma
, low-grade (G1 and G2) and high-grade (G3) which denotes the grade of the tumour, ranging from well-differentiated (G1) to moderately differentiated (G2) and finally poorly differentiated (G3).
Nonfocal branching or arborization of the folds should not be seen, though, and in such cases a diagnosis of a low-grade papillary urothelial neoplasm (eg, urothelial papilloma
or papillary urothelial neoplasm of low malignant potential [PUNLMP]) should strongly be considered.
Simplified 2004 World Health Organization Histologic Classification of Urothelial Tumors (a) Noninvasive Urothelial Neoplasm Papillary type * Urothelial papilloma
, including inverted type * Papillary urothelial neoplasm of low malignant potential * Low-grade, papillary urothelial carcinoma * High-grade, papillary urothelial carcinoma Nonpapillary type * Urothelial carcinoma in situ Invasive Urothelial Carcinoma (a) Excerpted from Eble et al, 2 2004.
(1) We present an unusual, to our knowledge previously unreported, urothelial tumor arising in the renal pelvis with a prominent cribriform growth pattern akin to ACC and theorize that it may represent a variant of inverted urothelial papilloma
(IUP) displaying a prominent cystic change or florid ureteritis cystica.
The differential diagnosis of the surface lesions with papillary architecture includes urothelial papilloma
, papillary urothelium neoplasm with low malignant potential, and low-grade papillary urothelial carcinomas.
Among these, 37 of 104 cases (35.6%) had recurrence as LG-UrCa or a lower-grade urothelial neoplasm (ie, urothelial papilloma
or PUNLMP) according to the 2004 WHO/ISUP classification and 19 of 104 cases (18.3%) demonstrated grade progression, developing HG-UrCa in one or more recurrence episode.
In addition to inverted urothelial papilloma
, which can sometimes have cystic areas, the differential diagnosis of these related lesions centers on variants of invasive urothelial carcinoma that have glandular features, including invasive urothelial carcinoma with glandular differentiation, the microcystic variant, and the tubular variant, as well as invasive adenocarcinoma.
Expression of cytokeratin 20 redefines urothelial papillomas
of the bladder.