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

Leiomyoma
J. Cheville
Definition
A benign mesenchymal tumour occurring
in the bladder wall showing smooth
muscle differentiation.
ICD-O code 8890/0
Epidemiology
Leiomyoma of the urinary bladder is the
most common benign mesenchymal
neoplasm of the urinary bladder {908,
1255,1338}. Unlike sarcomas of the bladder,
there is a predominance of females
{908}. There is a wide age range from
children to the elderly, but the vast majority
of patients are middle-aged to older
adults.
Clinical features
Patients present most frequently with
obstructive or irritative voiding symptoms,
and occasionally haematuria.
Macroscopy
Most leiomyomas are small with a mean
A
Fig. 2.80 A, B Lobulated giant leiomyoma.
size less than 2 cm {1338}. Tumours up
to 25 cm have been reported {908}.
Grossly, the tumours are circumscribed,
firm, and lack necrosis.
Histopathology
Histopathological features include well
formed fascicles of smooth muscle. Leiomyoma
of the bladder is circumscribed
with low cellularity, lack of mitotic activity
B
and bland cytologic features {1639}.
They are immunoreactive to smooth muscle
actin and desmin.
Prognosis
Patients are treated by transurethral
resection for small tumours, and open
segmental resection for larger tumours.
Surgical removal is curative in all cases.
Other non-epithelial tumours
J. Cheville
Malignant mesenchymal neoplasms
such as malignant peripheral nerve
sheath tumour, liposarcoma, chondrosarcoma
and Kaposi sarcoma can
very rarely involve the bladder {1410}.
The diagnosis of primary liposarcoma
and malignant peripheral nerve sheath
tumour of the bladder requires that bladder
involvement by direct extension from
another site be excluded. In the case of
primary bladder osteosarcoma and
chondrosarcoma, sarcomatoid carcinoma
must be excluded. Solitary fibrous
tumour of the bladder of the urinary bladder
has recently been recognized
{159,502,2808}. Solitary fibrous tumour
of the bladder occurs in older patients
who present with pain or haematuria. Two
of the seven cases that have been
reported were incidental findings {2808}.
The tumour is typically a polypoid submucosal
mass. Histopathologic features
include spindle cells arranged haphazardly
in a variably collagenous stroma.
Dilated vessels reminiscent of haemangiopericytoma
are present. Solitary
fibrous tumour at other sites can act in an
aggressive manner, but all solitary
fibrous tumours of the bladder have had
a benign course, although the number of
cases is small, and follow-up has been
short term in several cases.
Fig. 2.81 Solitary fibrous tumour of urinary bladder.
144 Tumours of the urinary system