Cardiac fibroma is the second most common primary benign cardiac tumor of childhood (after rhabdomyoma), accounting for 12-16% of pediatric cardiac tumors. It is rarely encountered in adults. It typically presents as a single, large (3-10 cm), well-circumscribed, unencapsulated, solid intramural mass in the left ventricular free wall or interventricular septum. Histopathologically, it consists of homogeneous fibrous tissue composed of fibroblasts and collagen fibers; calcification is quite common (25-50%) and is a diagnostic feature of the tumor. Marked T2 hypointensity (fibrous structure) and intense/diffuse LGE on MRI are the most characteristic imaging findings. It may be associated with Gorlin syndrome (nevoid basal cell carcinoma syndrome) — PTCH1 gene mutation is present in this syndrome. Unlike rhabdomyoma, it does not undergo spontaneous regression.
Age Range
0-10
Peak Age
2
Gender
Equal
Prevalence
Rare
Cardiac fibroma is considered a hamartomatous/neoplastic lesion arising from abnormal proliferation of fibroblasts and collagen fibers. In Gorlin syndrome-associated cases, PTCH1 (Patched-1) gene mutation leads to overactivation of the Hedgehog signaling pathway, increasing fibroblast proliferation. The dense collagen content (Type I and Type III collagen) forms the basis of T2 hypointensity on MRI — short T2 relaxation time results from low mobility of bound water protons. The expanded interstitial space between collagen fibers provides an ideal environment for gadolinium contrast accumulation, hence intense and diffuse enhancement on LGE sequences — this finding is the most diagnostic MR feature of fibroma. Intratumoral calcification develops through dystrophic calcification mechanism and appears as high-density foci on CT. Despite the absence of a capsule, the tumor is well-circumscribed and does not infiltrate surrounding myocardium; however, its large size can lead to conduction system disturbance (arrhythmias) and ventricular wall deformation.
The pathognomonic MR finding pair of cardiac fibroma: marked hypointensity on T2-weighted sequences (dense collagen, low free water) and intense diffuse enhancement on LGE sequences (gadolinium accumulation in expanded collagen interstitium). The combination of these two findings is not seen in any other cardiac tumor and virtually confirms fibroma diagnosis. Rhabdomyoma is T2 mildly hyperintense + LGE negative, myxoma is T2 markedly hyperintense + LGE heterogeneous — these differences establish the differential diagnosis.
On echocardiography, a single, large (typically 3-10 cm), well-circumscribed, homogeneous, mildly hyperechoic intramural mass in the left ventricular free wall or interventricular septum. May show similar echogenicity to myocardium with very homogeneous internal structure. Markedly hyperechoic foci with posterior acoustic shadowing may be seen in areas of calcification. The large tumor size may narrow the ventricular cavity and obstruct the left ventricular outflow tract.
Report Sentence
Echocardiography demonstrates a _x_ cm homogeneous, well-circumscribed, intramural solid mass in the left ventricular free wall. Hyperechoic foci with acoustic shadowing consistent with calcification are present within the mass.
On non-contrast CT, a soft tissue density (40-60 HU), well-circumscribed, large intramural mass in the left ventricular wall or septum. The most important CT finding is punctate, coarse, or central calcification within the mass (25-50%) — calcification in pediatric cardiac tumors is virtually pathognomonic for fibroma. Homogeneous soft tissue density is seen in non-calcified areas. The tumor expands the ventricular wall and compresses the cavity.
Report Sentence
CT demonstrates a _x_ cm soft tissue density, well-circumscribed intramural mass in the left ventricular free wall. Coarse and punctate calcifications are present within the mass.
On T1-weighted sequences, fibroma shows isointense or mildly hypointense signal relative to myocardium. Signal pattern is homogeneous — hemorrhage or necrosis is not expected. Calcification areas appear as signal void. Tumor boundaries may not be clearly delineated on T1 due to minimal signal difference from surrounding myocardium — T2 and LGE have greater diagnostic value.
Report Sentence
On T1-weighted sequences, an intramural mass showing isointense homogeneous signal relative to myocardium is seen in the left ventricle.
On T2-weighted sequences, fibroma shows markedly hypointense signal relative to myocardium — this finding is the most characteristic and pathognomonic MR feature of cardiac fibroma. Low T2 signal reflects the dense collagen structure and low free water content. Homogeneous hypointensity is typical. A peripheral thin hyperintense rim (reactive edema or tumor-myocardium transition zone) may be seen. This marked T2 hypointensity is the most valuable criterion for differentiating fibroma from rhabdomyoma (T2 mildly hyperintense) and myxoma (T2 markedly hyperintense).
Report Sentence
On T2-weighted sequences, the intramural mass in the left ventricle shows markedly hypointense signal consistent with dense fibrous structure. A peripheral thin hyperintense rim is present.
On LGE sequences, fibroma shows intense and diffuse enhancement — this finding, combined with T2 hypointensity, is the diagnostic MR pair for cardiac fibroma. Enhancement is homogeneous and encompasses the entire tumor. No enhancement in surrounding myocardium (absence of invasion). This intense LGE pattern is definitively distinguishing from rhabdomyoma's absent enhancement and myxoma's heterogeneous enhancement. The peripheral hyperintense rim (also seen on T2) may be more conspicuous on LGE.
Report Sentence
On LGE sequences, the intramural mass in the left ventricle shows intense and diffuse enhancement; consistent with cardiac fibroma. No pathological enhancement in surrounding myocardium.
On cine SSFP sequences, a large, well-circumscribed intramural mass in the left ventricular wall is seen. The tumor moves with the myocardium without independent mobility. In large lesions, ventricular wall thickening and cavity narrowing are prominent. Segmental wall motion decrease (akinesis or hypokinesis) may be seen in systole — reflecting the tumor's disruption of myocardial contractility. In septum-located fibromas, the right ventricular cavity may also be compressed.
Report Sentence
On cine SSFP sequences, a large intramural mass in the left ventricular wall is seen with segmental wall motion abnormality and cavity narrowing at the mass location.
Criteria
Isolated cardiac fibroma without Gorlin syndrome association. Majority of cases. PTCH1 mutation absent. Without dermatological or skeletal findings.
Distinct Features
Single lesion, no Gorlin syndrome findings. Recurrence rare after surgery. Excellent prognosis after surgical resection.
Criteria
PTCH1 gene mutation. Association with nevoid basal cell carcinomas, odontogenic keratocysts, skeletal anomalies (bifid rib, spina bifida occulta), falx cerebri calcification. Autosomal dominant inheritance.
Distinct Features
Systemic syndrome findings, multisystem approach required, genetic counseling and family screening recommended, dermatological follow-up (basal cell carcinoma risk).
Criteria
Fibroma occupying a large portion of the ventricular wall (>5 cm) causing severe cavity compression and outflow tract obstruction. Surgical resection may be technically challenging; heart transplantation may be required.
Distinct Features
Severe hemodynamic compromise, high arrhythmia risk, surgical difficulty, may be transplant candidate. MR planning critical.
Distinguishing Feature
Rhabdomyoma is multiple, T2 mildly hyperintense (glycogen), shows no LGE, TSC-associated, and undergoes spontaneous regression. Fibroma is single, T2 markedly hypointense (collagen), shows intense LGE, Gorlin syndrome-associated, and does not regress.
Distinguishing Feature
Myxoma is intracavitary (atrial), pedunculated, mobile, T2 markedly hyperintense (mucopolysaccharide), shows heterogeneous enhancement. Fibroma is intramural (ventricular), immobile, T2 markedly hypointense (collagen), shows intense diffuse LGE.
Distinguishing Feature
Sarcoma has irregular borders, infiltrative, extends to pericardium/mediastinum, heterogeneous T2 signal (necrosis + hemorrhage), shows high FDG uptake on PET. Fibroma is well-circumscribed, non-invasive, homogeneous T2 hypointense, with low metabolic activity.
Urgency
urgentManagement
surgicalBiopsy
Not NeededFollow-up
6-monthCardiac fibroma does not undergo spontaneous regression unlike rhabdomyoma, therefore surgical resection is the standard treatment in symptomatic cases. Close clinical and echocardiographic follow-up (6-month intervals) may be applied for asymptomatic small fibromas. In large fibromas, ventricular outflow tract obstruction, arrhythmias (ventricular tachycardia, sudden cardiac death), and heart failure may develop — urgent surgical resection is required. In septum-located or giant fibromas, surgical resection may not be feasible and heart transplantation may be needed. Gorlin syndrome (PTCH1 mutation) evaluation should be performed in all cases; if syndrome is identified, dermatological follow-up (basal cell carcinoma), dental follow-up (keratocyst), and genetic counseling should be initiated.
Cardiac fibroma does not show spontaneous regression and surgical resection is the primary treatment. Complete resection offers excellent prognosis — recurrence is very rare. Surgical indication is clear in symptomatic patients (arrhythmia, obstruction). Even in asymptomatic patients, surgery should be considered due to the risk of sudden cardiac death (ventricular arrhythmia). Subtotal resection may be necessary (in giant lesions of the interventricular septum) — residual tumor carries arrhythmia risk and ICD implantation should be considered. In suspected Gorlin syndrome, PTCH1 gene mutation screening and dermatologic evaluation should be performed.