Cardiac rhabdomyoma is
the most common benign congenital cardiac tumour. Visit:
Extracardiac
Rhabdomyoma
It is thought that the
tumour is a hamartoma rather than a true neoplasm.
This is the most common tumour
in infants and children.
Cardiac rhabdomyoma is
caused by mutations in the TSC1 and TSC2 genes.
The tumour is
closely associated with tuberous sclerosis and occurs in more than 50% of
patients with this disease.
Site: Any chamber of the heart
may be affected. The left ventricle is the most frequently involved site.
Clinical
presentation:
Clinical
profile varies from still-birth to intrauterine myocardial infarct (due to
coronary artery compression).
Cardiac rhabdomyoma is
frequently multiple and asymptomatic, but the tumour may cause
cardiomegaly,
heart failure by
causing outflow obstruction, arrhythmias, thromboembolic disease
or sudden unexpected death.
Gross features:
The tumour may present as a single or multiple , non-capsulated soft
lesion which can be easily distinguished from the surrounding myocardium.
Diffuse rhabdomyoma are extremely rare.
Large tumours may show intracavitary extension with almost
obliteration of the cavity (D/D: may be confused with cardiac myxoma).
Microscopic
features: Image Link1
;
Image Link2
;
Image Link3
;
Image Link4
Histologically the
tumour is composed of 'spider cells' .
Spider cells are large
swollen myocytes
with clear cytoplasm
and
centrally placed cytoplasmic mass and nucleus, connected with the
periphery of the cell by strands of cytoplasm
.
The spider cells are surrounded by normal cardiac myocytes.
Fate of the
tumour:
Cardiac rhabdomyoma
decreases in size with age.
Echocardiographic evaluation
has confirmed the spontaneous regression with eventual disappearance
of cardiac rhabdomyoma.
Hence, cardiac surgery
should be delayed to see whether or not the tumour would regress.
Such biologic
behavior supports the concept that cardiac rhabdomyomas are hamartoma
rather than a true neoplasm.
Differential diagnosis:
- Glycogen storage
disease (shape of the cardiomyocytes are well preserved ).
- Purkinje
cell tumour (Foamy
myocardial transformation)
- Hamartoma (no
cytoplasmic vacuolation). |
