Urothelial dysplasia

Urothelial dysplasia, also low-grade (urothelial) dysplasia, is a lesion of the urothelium in the ISUP/WHO 2004 classification.

Urothelial dysplasia
Diagnosis in short
Urothelial dysplasia. H&E stain.
Synonyms	low-grade urothelial dysplasia
LM	mild nuclear enlargement (~3x a resting lymphocyte) and hyperchromasia, mild disorganization of the architecture (some maturation), occasional mitotic figures - none atypical
LM DDx	reactive changes, urothelial atypia of unknown significance, urothelial carcinoma in situ
IHC	CK20 +ve/-ve (esp. non-umbrella cells), Ki-67 +ve/-ve (>10%), p53 +ve/-ve (>20%)
Site	urothelium (renal pelvis, urinary bladder, ureters, urethra)
Prevalence	common
Prognosis	pre-malignant

It is precursor lesion to urothelial carcinoma that is less worrisome than urothelial carcinoma in situ (also known as high-grade (urothelial) dysplasia).

General

The ISUP/WHO classification of flat urothelial lesions is:

• Reactive urothelial atypia.
• Flat urothelial hyperplasia.
• Urothelial atypia of unknown significance.
• Urothelial dysplasia (low-grade dysplasia).
• Urothelial carcinoma in situ (high-grade dysplasia).
• Invasive urothelial carcinoma.

Microscopic

Features:

• Mild nuclear enlargement (~3x a resting lymphocyte) and hyperchromasia.
• Slight disorganization of the architecture.
  • Some maturation to the surface - important.
• Mitotic figures - occasional, none atypical.

Notes:

• It is probably not a good idea to make this diagnosis without immunohistochemistry.
• This diagnosis not made on frozen section.

DDx:

• Benign urothelium with reactive changes.
• Urothelial carcinoma in situ - no maturation to the surface or marked atypia - as in pagetoid UCIS and undermining UCIS.

Images

• 

  UD - low mag. (WC)

• 

  UD - intermed. mag. (WC)

• 

  UD - high mag. (WC)

• 

  UD - high mag. (WC)

• 

  UD - very high mag. (WC)

• 

  UD - intermed. mag. (WC)

• 

  UD - high mag. (WC)

www:

• Urothelial dysplasia (jhu.edu).

IHC

There is a small literature on IHC for dysplasia versus UCIS. It is published in lesser known journals but suggests:

• p63 -ve at surface in dysplasia.
  • p63 +ve at surface in UCIS

A comparison between benign, dysplasia and UCIS:

Diagnosis	CK20	Ki-67	p53
Benign (reactive)	umbrella cells +ve only	-ve <=10% of cells (+/-rare basal cells)	-ve <20% of cells (+/-weak staining)
Urothelial dysplasia	+ve non-umbrella cells +ve (~30% of cases)	+ve >10% of cells (~40% of cases)	+ve >=20% of cells (~70% of cases)
Urothelial carcinoma in situ (UCIS	+ve non-umbrella cells (~70% of cases)	+ve >10% of cells (~95% of cases)	+ve >=20% of cells (~80% of cases)

Note:

• Morphology is considered the gold standard for UCIS versus urothelial dysplasia.^{[citation needed]}

Sign out

A. RIGHT URETER (MARGIN), EXCISION: 
- UROTHELIAL DYSPLASIA, SEE COMMENT.
- NEGATIVE FOR UROTHELIAL CARCINOMA.

COMMENT:
There is focal non-umbrella cell CK20 staining, 10% (focal) urothelial 
p53 staining, and 30% (focal) urothelial Ki-67 staining. The findings 
are that of (low-grade) urothelial dysplasia.

See also

• Urothelium.