Discussion
Primary cardiac tumors in childhood are extremely rare and detected
tumors with a rate of 0.08% in autopsies, and are mostly benign. The
most common histologically seen infantile cardiac tumors are rhabdomyoma
(60% -85%) and according to their incidence, teratoma, fibroma,
hemangioma and hamartomas, respectively. 4-6. In the
last two decades, an increase in the incidence of pediatric cardiac
tumors has been reported due to the increase in noninvasive imaging
methods, the technological development of TTE devices and the widespread
use of them. Patients admission complaints depend on the size and
localization of the mass, as they have an inlet or outlet obstruction
and arrhythmogenic effect 7. In general, the
indications for resection are to eliminate hemodynamic and respiratory
pathologies, if any, severe arrhythmia and a significant risk of
embolization. These tumors are highly associated (60-80%) with TSC. It
originates from the free wall of the ventricle and ventricular septum.
The diagnosis of rhabdomyom is based on the characteristic TTE features
of the tumor, in addition to the cutaneous, central nervous system or
renal manifestations of tuberous sclerosis. In TTE examination, they are
seen as well-circumscribed, homogeneous and echo bright masses. Many
studies have shown that rhabdomyomas that are medically followed and
partially resected will regress spontaneously within 1 to 3 years.
The patient we presented had AVSD and PDA accompanying rhabdomyoma. In
the literature, the patient with congenital heart defect associated with
TS and rhabdomyom is very rare. In the study published by Jiang et al.3, they mentioned that the heart may disrupt the
growth pattern in the region where the mass appeared during the
embryological development phase. In our case, since the intrauterine
cardiac examination was not performed, it cannot be clearly revealed in
which trimester the rhabdomyoma occurred. However, the atrioventricular
canal defect and the area where the rhabdomyom is located are very
close, suggesting that the tumor may have caused the supposed
development defect.
In the literature, it has been observed that the rhabdomyoma associated
with the TSC is largely multiple. However, we observed a solitary
rhabdomyom in our case. In the study conducted by Bader et al. with 26
patients, the tumors in diagnosis were single in 5 patients (19%)
including right or left ventricle and multiple in 21 patients (80.8%)8. In a study conducted by Sciacca et al. with 33
patients, multiple rhabdomyomas were detected in all tuberous sclerosis
patients 9. It is well known that AV channel defects
often coexist with down syndrome. However, in our case, the absence of
down syndrome is also interesting.
We did not excise rhabdomyoma in our patient, since it was asymptomatic,
was largely intramyocardial, and would cause destruction in the
surrounding structures during excision. Malign arrhythmias that may
develop in the postoperative period after excision could be fatal. After
birth, rhabdomioma cells lose their ability to divide, and tumor
regression in infancy is an expected result regardless of tumor size. In
more than 80% of tumors, full regression can occur in early childhood.
In addition, it has been revealed by many studies everolimus, an mTOR
inhibitor, have shown that this drug accelerates shrinkage in the size
of rhabdomiomas by up to 12 times 10,11.