Urachal carcinoma

Urachal carcinoma
Diagnosis in short
Urachal carcinoma (right of image) and benign urothelium (left of image). H&E stain.
LM	atypical cells - usually gland forming, +/-mucinous component, +/-signet rings
Subtypes	enteric, mucinous, signet ring
LM DDx	adenocarcinoma of the urinary bladder, invasive urothelial carcinoma with glandular differentiation, metastatic adenocarcinoma
IHC	CK20 +ve, beta-catenin +ve (non-nuclear), p63 -ve, CK34betaE12 +ve
Site	urachus, urinary bladder - specifically the dome
Signs	+/-hematuria
Prevalence	very rare
Prognosis	usually poor
Clin. DDx	other bladder tumours - esp. urothelial carcinoma

Urachal carcinoma is an uncommon malignant tumour that arises from the urachus. Most urachal carcinomas are adenocarcinomas.

General

• Very rare~ 0.2% of bladder cancers.
• Often younger <55 years-old.

Treatment:

• Partial cystectomy +/- umbilectomy.

Gross

• Lesion must be in urachus or dome of urinary bladder.

Microscopic

Features of epithelial malignancy:

• Atypical (epithelial) cells.
  • May be signet ring cells.
• Usually gland forming, i.e. adenocarcinoma.
• +/-Mucinous component.

Features making it urothelial carcinoma (modified Sheldon criteria) - all required:

1. Located in bladder dome or anterior wall.
2. Centered on bladder wall (as opposed to the mucosa).
3. No widespread cystitis cystica/glandularis outside of the bladder dome and anterior wall.
4. No known urothelial carcinoma elsewhere.

DDx:

• Adenocarcinoma of the urinary bladder.
• Invasive urothelial carcinoma with glandular differentiation.
• Metastatic adenocarcinoma/adenocarcinoma extending from another structure, e.g. colorectal adenocarcinoma.

Patterns

• Enteric - looks like colonic adenocarcinoma.
• Mucinous.
• Signet ring.

Note:

• Urachal carcinoma may be nonglandular.

Images

• 

  UC - very low mag. (WC)

• 

  UC - low mag. (WC)

• 

  UC - high mag. (WC)

IHC

Features:

• CK20 +ve.
• CK7 +ve/-ve.
• CK34betaE12 +ve/-ve.
• Beta-catenin -- usu cytoplasmic/membranous +ve.

Others:

• p63 -ve (+ve in only 3%).

UC versus CRC -- not absolute but useful:

• CK34betaE12 +ve in UC (-ve in CRC).
• Beta-catenin -ve nuclei in UC (+ve nuclei in CRC).

Sign out

• The diagnosis is a clinicopathologic diagnosis - one needs imaging to make it.
• May be staged with the Sheldon system.

Sheldon staging system

Staging as Sheldon et al.:

• pT1 - confined to urachal mucosa.
• pT2 - confined to the urachus.
• pT3a - extension into the bladder wall
• pT3b - extension into the abdominal wall.
• pT3c - structures other than the bladder.
• pT4a - metastasis to regional lymph nodes.
• pT4b - metastasis to distant sites.

See also

• Urinary bladder.
• Urothelium.
• Adenocarcinoma of the urinary bladder.