Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

A
B
Fig. 2.65 Intramural urachal canal without complexity,
covered by urothelium.
C
Fig. 2.64 Adenocarcinoma. A Mucinous (colloid) pattern of adenocarcinoma of the urachus with its characteristic
mucin pool. B Primary urachal adenocarcinoma, intestinal type with complex atypical glands infiltrating
the bladder wall. C Malignant cells floating in a mucin pool, a characteristic finding in mucinous (colloid)
adenocarcinoma of the urachus. D Mucinous (colloid) pattern of adenocarcinoma of the urachus with
malignat cells floating in a mucin pool.
Staging
Although urachal adenocarcinoma has
been staged as a bladder carcinoma
using the TNM staging system which is
difficult to apply because the majority of
urachal adenocarcinomas are "muscle
invasive". Hence, a specific staging system
for this neoplasm has been proposed
{2383}.
Histopathology
This discussion pertains mainly to adenocarcinomas
as the most common.
Urachal adenocarcinomas are subdivided
into mucinous, enteric, not otherwise
specified, signet ring-cell, and mixed
types; these subtypes are similar to those
Table 2.06
Staging system of the urachal carcinoma.
I. Confined to urachal mucosa
II. Invasive but confined to urachus
III. Local extension to:
A. Bladder muscle
B. Abdominal wall
C. Peritoneum
D. Other viscera
IV. Metastases to:
A. Regional lymph nodes
B. Distant sites
________
From Sheldon et al. {2383}.
D
of adenocarcinoma of the urinary bladder.
In one study with 24 cases of urachal
carcinoma, 12 (50%) tumours were mucinous,
seven (29%) were enteric, four
(17%) were mixed, and one (4%) was a
signet ring-cell carcinoma {953}.
Mucinous carcinomas are characterized
by pools or lakes of extracellular mucin
with single cells or nests of columnar or
signet ring-cells floating in it. The enteric
type closely resembles a colonic type of
adenocarcinoma and may be difficult to
differentiate from it. Pure signet ring-cell
carcinoma rarely occurs in the urachus;
most commonly, signet ring-cell differentiation
is present within a mucinous
carcinoma.
The cells of urachal adenocarcinoma
stain for carcinoembryonic antigen
{24,953}, and Leu-M1 {24,953}.
Criteria to classify a tumour as urachal in
origin were initially established by
Wheeler and Hill in 1954 {2811} and consisted
of the following: (1) tumour in the
dome of the bladder, (2) absence of cystitis
cystica and cystitis glandularis, (3)
invasion of muscle or deeper structures
and either intact or ulcerated epithelium,
(4) presence of urachal remnants, (5)
presence of a suprapubic mass, (6) a
sharp demarcation between the tumour
and the normal surface epithelium, and
(7) tumour growth in the bladder wall,
branching into the Retzius space. These
criteria, believed to be very restrictive,
were modified by Johnson et al. {1230},
who proposed the following criteria: (1)
tumour in the bladder (dome), (2) a
sharp demarcation between the tumour
and the surface epithelium, and (3)
exclusion of primary adenocarcinoma
located elsewhere that has spread secondarily
to the bladder. Bladder adenocarcinoma
may be very difficult to rule
out because it has the same histologic
and immunohistochemical features as
urachal adenocarcinoma does. Urachal
adenocarcinoma may be associated with
cystitis cystica and cystitis glandularis;
the cystitis cystica or cystitis glandularis
must show no dysplastic changes, however,
because dysplastic changes of the
mucosa or presence of dysplastic intestinal
metaplasia would tend to exclude
an urachal origin.
Precursor lesion
The pathogenesis of urachal adenocarcinoma
is unknown. Although a urachal
adenocarcinoma may arise from a villous
adenoma of the urachus {1571}, intestinal
metaplasia of the urachal epithelium is
believed to be the favoured predisposing
factor {201}.
Prognosis
Management of urachal adenocarcinoma
consists of complete eradication of
the disease. Partial or radical cystectomy,
including the resection of the umbilicus,
is the treatment of choice.
Recurrences, are common, however,
especially in cases in which a partial cystectomy
is done {878,2853}. Examination
of the surgical margins with frozen section
has been advocated {878}. The 5
year survival rate has been reported to
range from 25% {2813} to 61% {953}.
132 Tumours of the urinary system