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Cardiac Tumors & Carcinoid Heart Disease

Name: Cardiac Tumors & Carcinoid Heart Disease
Creator: Veli Bakalov, MD

Myxoma, rhabdomyoma, and the serotonin that scars the right heart

Cardiovascular·Myocardial, Valvular & Pericardial Disease·4 min read·8 high-yield points·Reviewed by Veli Bakalov, MD @HemeOncBuddy

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Metastases (lung, breast, lymphoma, leukemia, melanoma) are the most common cardiac tumors and usually present as a hemorrhagic pericardial effusion or tamponade.
Myxoma is the most common primary cardiac tumor in adults: a pedunculated left atrial mass near the fossa ovalis made of stellate cells in myxoid stroma.
Myxoma causes positional ball-valve obstruction with an early diastolic tumor plop, systemic emboli, and IL-6-driven fever, weight loss, and high ESR.
Multiple, recurrent, or early-onset myxomas with spotty pigmentation and endocrine overactivity suggest Carney complex (PRKAR1A).
Rhabdomyoma is the most common primary cardiac tumor in children: multiple ventricular hamartomas of tuberous sclerosis (TSC1/TSC2) that often regress.
Papillary fibroelastoma is the most common valve tumor and embolizes; angiosarcoma is the most common primary malignant cardiac tumor and arises in the right atrium.
Carcinoid heart disease requires hepatic metastases, which let serotonin reach the right heart and cause tricuspid regurgitation and pulmonic stenosis.
Lung monoamine oxidase spares the left heart unless there is a PFO or ASD, a bronchial carcinoid, or a very high hormone burden; urine 5-HIAA confirms carcinoid syndrome.

Secondary and primary cardiac tumors

Metastases first. Metastases are by far the most common tumors in the heart. The usual sources are lung and breast carcinoma, lymphoma, leukemia, and melanoma, which has the highest rate of cardiac spread. They usually involve the pericardium rather than forming an intracardiac mass. The presentation is a hemorrhagic pericardial effusion, sometimes with tamponade, which tends to recur; cytology of the fluid can establish the diagnosis.

Primary cardiac tumors

Tumor	Patient	Location	Signature
Myxoma	Adults, often middle-aged women	Left atrium, stalk on septum near fossa ovalis	Ball-valve obstruction, emboli, IL-6 symptoms; Carney complex
Rhabdomyoma	Infants and children	Ventricles, often multiple	Tuberous sclerosis; spider cells; often regresses
Papillary fibroelastoma	Older adults	Valve surfaces (aortic > mitral)	Frond-like "sea anemone"; embolic stroke
Angiosarcoma	Adults	Right atrium	Most common primary malignancy; hemorrhagic effusion

Atrial myxoma

Pathology. Myxoma is the most common primary cardiac tumor in adults, most often affecting middle-aged women. About 75–80% arise in the left atrium, attached by a stalk to the interatrial septum near the fossa ovalis. The gelatinous, friable mass consists of stellate (lepidic) cells scattered in abundant mucopolysaccharide (myxoid) ground substance.

Ball-valve obstruction. The mobile tumor prolapses into the mitral orifice during diastole and obstructs left ventricular filling. Symptoms are positional: dyspnea, presyncope, or syncope. A low-pitched early diastolic "tumor plop," often mistaken for an opening snap or S3, may be accompanied by a mitral stenosis–like rumble that varies with posture.

Emboli and constitutional symptoms. Friable fragments embolize to the brain and limbs, and right atrial myxomas embolize to the lungs. Tumor cells secrete IL-6, producing fever, weight loss, fatigue, anemia, a high ESR, and hypergammaglobulinemia. The picture mimics endocarditis or vasculitis and resolves after resection. Echocardiography makes the diagnosis, and surgical excision is the treatment.

Carney complex. This autosomal dominant syndrome results from loss of PRKAR1A, the regulatory subunit of protein kinase A, which leaves PKA signaling overactive. Suspect it when myxomas are multiple, recurrent, in unusual chambers, or in young patients. Associated features are spotty skin pigmentation (lentigines, blue nevi), cutaneous myxomas, and endocrine overactivity: Cushing syndrome from primary pigmented nodular adrenocortical disease, acromegaly, and testicular tumors. Familial myxomas recur, so patients and first-degree relatives need echocardiographic surveillance.

Other primary tumors

Rhabdomyoma. This is the most common primary cardiac tumor in infants and children. It forms multiple ventricular, often septal, hamartomas that are strongly associated with tuberous sclerosis (loss of TSC1 hamartin or TSC2 tuberin, which releases mTOR). Histology shows large glycogen-rich "spider cells," with cytoplasmic strands radiating from a central nucleus to the cell membrane. Because many regress spontaneously, treatment is reserved for outflow obstruction or arrhythmia. Cardiac fibroma, in contrast, is a solitary ventricular tumor of childhood linked to Gorlin syndrome.

Papillary fibroelastoma. This is the most common tumor of the heart valves, usually found in older adults on the aortic valve, less often the mitral. Small, frond-like, avascular papillae of collagen and elastic fibers covered by endothelium give it a sea-anemone appearance. Fronds and adherent thrombus embolize, causing TIA, stroke, or coronary occlusion, so resection is advised when it is symptomatic or mobile.

Angiosarcoma. This is the most common primary malignant cardiac tumor in adults. It usually arises in the right atrium, invades the pericardium, and presents with a hemorrhagic effusion, tamponade, or right-heart failure. It is CD31-positive and often metastatic at diagnosis.

Carcinoid heart disease

Midgut carcinoidSerotonin released into portal blood is inactivated by hepatic monoamine oxidase on first pass, so gut tumors alone rarely affect the heart.
Hepatic metastasesSerotonin, tachykinins, and bradykinin drain straight into the hepatic veins and IVC.
Right heart exposedSerotonin acting on 5-HT2B receptors stimulates fibroblast proliferation on the endocardium and valves.
Lungs filterPulmonary monoamine oxidase inactivates serotonin, sparing the left heart.

The lesion. Pearly-white fibrous plaques of myofibroblasts in a mucopolysaccharide-rich matrix coat the endocardium and valves without destroying the underlying architecture. Thickened, retracted, fixed tricuspid leaflets cause tricuspid regurgitation, the most common lesion, and a narrowed pulmonic valve causes pulmonic stenosis. The result is right heart failure with jugular venous distension, hepatomegaly, and edema.

When the left side is involved. Left-sided plaques imply that serotonin bypassed the lungs. This happens through a patent foramen ovale or ASD with right-to-left shunting, favored by high right atrial pressure; with a bronchial carcinoid that drains directly into the pulmonary veins; or with a very high hormone burden.

Diagnosis and treatment. Carcinoid syndrome (episodic flushing, secretory diarrhea, wheezing, and right-sided murmurs) is confirmed by an elevated 24-hour urine 5-HIAA, the serotonin metabolite. Heavy serotonin synthesis diverts tryptophan away from niacin production and can cause pellagra. Octreotide, a somatostatin analog, controls symptoms, and severely damaged valves are replaced surgically.

Serotonergic drugs cause a similar valvulopathy through 5-HT2B agonism: fenfluramine-phentermine and ergot-derived dopamine agonists such as pergolide and cabergoline.