statdx/docs_md/articles/rhabdomyoma_2915b0ba-a2fc-425c-beb7-2566dd945aed.md

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Rhabdomyoma	2915b0ba-a2fc-425c-beb7-2566dd945aed	key value 7e393d6e-f8be-4315-b1cd-b4639ee57a5f Randy R. Richardson, MD key value db1ca0c5-292f-4acd-847d-c73a4f4ba734 Ryan A. Moore, MD key value 961f3a7f-ad62-43bc-98f4-5116b17ab812 Paula J. Woodward, MD, FSRU	name slug treeNodeId Pediatrics pediatrics a915965c-d436-44cf-ae65-2f22e7246ea4 name slug treeNodeId Diagnosis diagnosis 2b5cea64-a083-489e-ac0c-ec14ba059026 name slug treeNodeId Cardiac cardiac 7b8bc469-b6b8-4b0c-a552-38a906099111 name slug treeNodeId Miscellaneous miscellaneous f9f94c98-8eb2-46eb-8552-909d84cb1df3 name slug treeNodeId Rhabdomyoma rhabdomyoma null	Pediatrics	702657a1-8298-4d26-8b2b-5c7249ecda7f	97f69fa2-7987-4883-9f4f-4275e92bab38	18	10/28/21	Rhabdomyoma	Pediatrics, Diagnosis, Cardiac, Miscellaneous, Rhabdomyoma	Rhabdomyoma | STATdx	Rhabdomyoma	DX	true	Pediatrics Diagnosis Cardiac Miscellaneous Rhabdomyoma

---

title: "Rhabdomyoma" docid: "2915b0ba-a2fc-425c-beb7-2566dd945aed" authors:

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---

KEY FACTS

• Terminology

  • Congenital cardiac hamartoma composed of abnormal myocytes

• Imaging

  • Initial diagnosis is often by fetal &/or postnatal echocardiogram - Homogeneous, hyperechoic mass(es) of myocardium - Intramyocardial: May appear as wall thickening - Intracavitary: Mass attached to myocardium protrudes into lumen
  • MR is leading diagnostic test to delineate location, extent, & tissue characteristics of cardiac masses in children - T1: Iso- or mildly hyperintense to myocardium - T2: Hyperintense to myocardium - 1st-pass perfusion: Hypointense to myocardium - Late gadolinium enhancement: Isointense to myocardium - Homogeneous appearance on all sequences
  • Normal chest radiograph in small masses - Cardiomegaly & signs of congestive heart failure in large masses
  • Image brain (MR) & kidneys (US) for findings of tuberous sclerosis complex (TSC) - ~ 100% of patients with multiple rhabdomyomas & 50% with single rhabdomyoma have TSC

• Top Differential Diagnoses

  • Fibroma; pericardial teratoma

• Clinical Issues

  • Cardiac tumors are rare in children
  • Rhabdomyoma is most common pediatric cardiac tumor
  • 75% are diagnosed before 1 year of age
  • Natural history: Up to 93% show spontaneous regression; 70% regress by 4 years of age
  • Surgical excision for minority of cases with refractory arrhythmias or hemodynamic compromise

TERMINOLOGY

• Definitions

  • Congenital cardiac hamartoma composed of abnormal myocytes

IMAGING

• General Features

  • Best diagnostic clue

    - Cardiac mass within or contiguous with myocardium
    

  • Location

    - Interventricular septum > left or right ventricular free wall > > atrium
    - Multiple in up to 90% of cases
    

  • Size

    - < 1 mm to 10 cm; most are 3-4 cm
    

  • Morphology

    - Well-circumscribed, nonencapsulated mass(es)
    - Intramural or exophytic
            - May involve entire wall & appear as wall thickening
    

• Radiographic Findings

  • Normal chest radiograph in small masses
  • Cardiomegaly & signs of heart failure in large masses

• Echocardiographic Findings

  • Often superior to MR for detection of small masses
  • Homogeneous, hyperechoic mass involving myocardium
  • No blood flow within mass
  • Most often in interventricular septum but can be anywhere
  • May appear as simple wall thickening
  • Intraluminal portion of mass may move across adjacent valve during cardiac cycle

• CT Findings

  • NECT

    - Often hypodense compared with myocardium
    

  • CECT

    - Intraluminal component may be assessed with contrast-enhanced studies
    

• MR Findings

  • T1WI

    - Iso- or mildly hyperintense to myocardium
    

  • T2WI

    - Hyperintense to myocardium
    - No change with fat saturation (rules out lipoma)
    

  • T1WI C+

    - Minimal initial enhancement (1st-pass perfusion)
    - Isointense to myocardium with late gadolinium enhancement (LGE)
    

  • SSFP cine

    - Help to differentiate tumor from contractile myocardium, evaluate hemodynamic effect of mass, & look for valvular leak
    

• Imaging Recommendations

  • Best imaging tool

    - Dedicated transthoracic echo in all cases
    - MR is helpful for diagnostic uncertainty, large masses, & surgical planning
    

  • Protocol advice

    - If cardiac mass is identified
            - Look for additional masses
            - Assess location & quality of mass
    - Look for rhythm abnormalities
            - Premature atrial or ventricular contractions are common
            - Supraventricular tachycardia
            - Sinus bradycardia
    - Look for signs of obstruction
            - Ventricular inflow or outflow obstruction
            - May manifest as valve regurgitation or stenosis
            - ↑ cardiac work to overcome obstruction → wall hypertrophy
    - Evaluate for other findings of tuberous sclerosis complex (TSC)
    - In fetus, monitor for signs of hydrops (poor function, effusions)
    

DIFFERENTIAL DIAGNOSIS

• Fibroma
  • Benign congenital cardiac neoplasm composed of fibroblasts & collagen
  • 2nd most common cardiac neoplasm in pediatric population after rhabdomyoma
  • Often arises from interventricular septum or left ventricular free wall
  • MR: Isointense on T1, hypointense on T2
• Teratoma
  • Pericardial (not myocardial) tumor
  • Exophytic growth (will not be in cardiac chamber)
  • Pericardial effusion is often present
  • Contains all 3 germ cell layers → may be very heterogeneous on imaging with cystic, fatty, & calcified components
• Lipoma
  • Most arise from endocardial surface & protrude into chamber lumen
  • Fat density/intensity on imaging studies allows for specific diagnosis
• Myxoma
  • Majority manifest in adulthood (4th-7th decades)
  • 90% are solitary & atrial in location - 75% in left atrium, 10-20% in right atrium - Predilection for interatrial septum adjacent to fossa ovalis
• Papillary Fibroelastoma

  • 90% involve valves

  • Typically small (< 15 mm)
• Cardiac Malignancies
  • Extremely uncommon in children
  • Sarcomas account for most (with angiosarcoma being most common)
  • Usually large masses with invasive features
  • Pericardial & pleural effusion are often present

PATHOLOGY

• General Features

  • Etiology

    - Unknown, but data suggests maternal hormones may play role in growth & development of fetal rhabdomyomas
            - Helps explain regression after delivery
    

  • Genetics

    - Nearly 100% of patients with multiple & 50% with single rhabdomyomas have TSC
    - TSC: Autosomal dominant with variable expressivity
            - ~ 30% of cases are inherited
            - Other cases are due to new mutation
    - Caused by mutations in *TSC1* or*TSC2* genes
            - *TSC1* is located on chromosome 9q
                      - Encodes for hamartin protein
                      - Complexes with tuberin to regulate cell cycle
            - *TSC2* located on chromosome 16p
                      - Encodes for tuberin protein
                      - Participates in normal brain development & cardiomyocyte differentiation
    

  • Associated abnormalities

    - Other findings of TSC
            - Brain: Subependymal nodules, cortical/subcortical tubers, subependymal giant cell astrocytoma
            - Lung: Lymphangioleiomyomatosis
            - Kidney: Angiomyolipomas & cysts
            - Eye: Retinal hamartomas
            - Nails: Ungual fibromas
    

  • Pathophysiology - Mass may interfere with myocardial contraction - Exophytic masses frequently obstruct blood flow or cause valvular insufficiency

• Gross Pathologic & Surgical Features

  • Well-circumscribed, intramyocardial or exophytic mass(es)

• Microscopic Features

  • Large, vacuolated myocytes
  • Glycogen-rich vacuoles stretch perinuclear cytoplasm (spider cells)

CLINICAL ISSUES

• Presentation

  • Most common signs/symptoms

    - Obstruction to blood flow → heart failure
    - Arrhythmias
    - Large intracavitary tumors causing turbulent flow → hemolytic anemia & thrombocytopenia
    

  • May be seen prenatally - Generally incidental finding - Rarely presents with arrhythmia or hydrops - Can detect as early as 22-weeks gestation - May discover more masses as pregnancy progresses - Tend to ↑ in size prenatally & then regress after birth

• Demographics

  • Age

    - 75% are diagnosed before 1 year of age
    

  • Epidemiology

    - Cardiac tumors rare (1:30,000-1:100,000)
    - Rhabdomyoma is most common pediatric cardiac tumor
    

• Natural History & Prognosis

  • Generally excellent with spontaneous regression in 70% of children by 4 years of age
  • Poor prognosis for untreated large masses interfering with cardiac hemodynamics - Most respond well to surgical excision - Case reports of response to mTOR (mammalian target of rapamycin) inhibitor sirolimus - mTOR: Protein kinase that regulates cellular proliferation; used to treat subependymal giant cell tumors & angiomyolipomas

• Treatment

  • Surgical excision should be considered only for those with refractory arrhythmias or hemodynamic compromise - Partial resection of intraluminal component of large exophytic masses may be necessary - 3D printing from CT/MR data can build heart model with tumor location & extent for easy visualization; can assist with procedural planning - Attempts at electrophysiology testing & ablation around tumor focus have variable success rates - 3D printed models have been helpful
  • Small, intramural masses with no hemodynamic effect typically need no treatment or surgical excision

DIAGNOSTIC CHECKLIST

• Consider

  • Overall prognosis is excellent
  • However, rhabdomyomas may cause significant morbidity from obstruction to inflow or outflow, ventricular dysfunction, or arrhythmias

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References

Selected References

1. Tsoumani Z et al: Magnetic resonance imaging of intramyocardial fat deposition in tuberous sclerosis. Diagnostics (Basel). 10(12), 2020
2. Victoria T et al: Imaging of fetal tumors and other dysplastic lesions: a review with emphasis on MR imaging. Prenat Diagn. 40(1):84-99, 2020
3. Poterucha TJ et al: Cardiac tumors: clinical presentation, diagnosis, and management. Curr Treat Options Oncol. 20(8):66, 2019
4. Ugurlucan M et al: Giant rhabdomyoma requiring emergency resection early after birth. Ann Thorac Surg. 107(1):e65, 2019
5. Chen J et al: Fetal cardiac tumors: fetal echocardiography, clinical outcome and genetic analysis in 53 cases. Ultrasound Obstet Gynecol. 54(1):103-9, 2018
6. Dragoumi P et al: Diagnosis of tuberous sclerosis complex in the fetus. Eur J Paediatr Neurol. 22(6):1027-34, 2018
7. Palaskas N et al: Evaluation and management of cardiac tumors. Curr Treat Options Cardiovasc Med. 20(4):29, 2018
8. von Ranke FM et al: Imaging of tuberous sclerosis complex: a pictorial review. Radiol Bras. 50(1):48-54, 2017
9. Ying L et al: Primary cardiac tumors in children: a center's experience. J Cardiothorac Surg. 11(1):52, 2016
10. Sciacca P et al: Rhabdomyomas and tuberous sclerosis complex: our experience in 33 cases. BMC Cardiovasc Disord. 14:66, 2014
11. Tao TY et al: Pediatric cardiac tumors: clinical and imaging features. Radiographics. 34(4):1031-46, 2014
12. Beroukhim RS et al: Characterization of cardiac tumors in children by cardiovascular magnetic resonance imaging a multicenter experience. J Am Coll Cardiol. 58(10):1044-54, 2011
13. Miyake CY et al: Cardiac tumors and associated arrhythmias in pediatric patients, with observations on surgical therapy for ventricular tachycardia. J Am Coll Cardiol. 58(18):1903-9, 2011
14. Tiberio D et al: Regression of a cardiac rhabdomyoma in a patient receiving everolimus. Pediatrics. 127(5):e1335-7, 2011
15. Jain D et al: Benign cardiac tumors and tumorlike conditions. Ann Diagn Pathol. 14(3):215-30, 2010
16. Yinon Y et al: Fetal cardiac tumors: a single-center experience of 40 cases. Prenat Diagn. 30(10):941-9, 2010
17. Burke A et al: Pediatric heart tumors. Cardiovasc Pathol. 17(4):193-8, 2008
18. Syed IS et al: MR imaging of cardiac masses. Magn Reson Imaging Clin N Am. 16(2):137-64, vii, 2008
19. Kellenberger CJ et al: Cardiovascular MR imaging in neonates and infants with congenital heart disease. Radiographics. 27(1):5-18, 2007
20. Sparrow PJ et al: MR imaging of cardiac tumors. Radiographics. 25(5):1255-76, 2005
21. Kiaffas MG et al: Magnetic resonance imaging evaluation of cardiac tumor characteristics in infants and children. Am J Cardiol. 89(10):1229-33, 2002
22. Grebenc ML et al: Primary cardiac and pericardial neoplasms: radiologic-pathologic correlation. Radiographics. 20(4):1073-103; quiz 1110-1, 1112, 2000

Images

Selected Images

Axial graphic shows a partially exophytic rhabdomyoma in the apex of the left ventricle (LV).

Axial graphic shows a partially exophytic rhabdomyoma in the apex of the left ventricle (LV).

Axial T1 MR was performed in an asymptomatic 8-year-old girl with tuberous sclerosis complex (TSC) after a routine screening echocardiogram showed an intracardiac mass. MR shows a round, well-demarcated, intraluminal mass originating from the free wall of the LV. It is slightly hyperintense to myocardium, a characteristic finding of rhabdomyomas.

Axial US through the fetal chest shows multiple echogenic, intracardiac masses involving both ventricles & the interventricular septum. Multiple rhabdomyomas are virtually diagnostic of TSC.

Axial CECT of the heart in a 15-year-old patient with a history of multiple rhabdomyomas shows complete involution of masses with only small fatty deposits now seen along the interventricular septum, consistent with known TSC.

Four-chamber view from a fetal echocardiogram shows an echogenic mass in the apex of the right ventricle (RV), most consistent with a rhabdomyoma. The patient was later diagnosed with TSC. A mass this size will likely have no physiologic effect on the cardiac function.

Gross pathology of the heart shows a well-defined mass arising from the wall of the ventricle. Histology confirmed a rhabdomyoma.

SSFP bright blood cine short-axis MR in a neonate demonstrates a large, hypointense rhabdomyoma within the RV wall .

SSFP cine short-axis MR in same patient at 13 years of age demonstrates near-complete resolution of the rhabdomyoma with minimal residual tumor . The RV appears borderline dilated, & the LV appears normal.

Postnatal axial US in a patient with tuberous sclerosis shows a large echogenic mass filling the LV. Rhabdomyomas are often large at birth but usually spontaneously regress postnatally.

Four-chamber view double IR image from a cardiac MR demonstrates an echogenic mass filling the LV, consistent with a rhabdomyoma. Masses of this size may have cardiac obstruction & heart failure. Note the marked enlargement of the heart in this neonate.

Additional Images

CT-derived 3D-printed heart model demonstrates a rhabdomyoma in the LV free wall of a teenager being considered for mass resection due to refractory ventricular tachycardia.

Postnatal echocardiogram in the parasternal long axis shows a large mass along the interventricular septum of the LV. Rhabdomyomas may grow during pregnancy but usually spontaneously regress postnatally.

Gross pathology shows a rhabdomyoma causing dramatic LV wall thickening. Rhabdomyomas can vary widely in size, number, & morphology.

Echocardiogram in a neonate with TSC shows persistence of multiple echogenic rhabdomyomas in the heart.

Four-chamber echocardiogram of the fetal heart shows a right atrial rhabdomyoma . This is a far less common location for rhabdomyoma than the ventricles.

Four-chamber fetal echocardiogram shows a large, echogenic solitary tumor in the ventricular septum, which makes both the left ventricular & RV volumes small.

Axial T1 MR of a newborn with an in utero diagnosis of a cardiac mass shows dramatic LV wall thickening . The infant was hemodynamically stable. The prognosis for rhabdomyomas is good if there are no complications in utero or in the first 6 months of life (as these lesions regress over time).

Follow-up axial T1 MR in the same patient at 2 years of age shows marked involution of the mass with residual wall thickening.