DOI: 10.1148/rg.251045059
RadioGraphics 2005;25:249-253
© RSNA, 2005
Cardiac Metastases from Melanoma1
Maude Tesolin, MD,
Chantale Lapierre, MD,
Luc Oligny, MD,
Jean-Luc Bigras, MD and
Martin Champagne, MD
1 From the Departments of Medical Imaging (M.T., C.L.), Pathology (L.O.), Cardiology (J.L.B.), and Hematooncology (M.C.), Hôpital Sainte-Justine, University of Montreal, 3175 Côte Ste-Catherine Rd, Montreal, Quebec H3T 1C5, Canada. Received March 30, 2004; revision requested April 27 and received May 27; accepted June 1. All authors have no financial relationships to disclose. Address correspondence to C.L. (e-mail: chantal_lapierre@ssss.gouv.qc.ca).
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History
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A 15-year-old girl presented with a skin nodular malignant melanoma on the back. The patient underwent wide local excision and lymphoscintigraphic lymph node samplings in April 2000. The Breslow index was 5.58 mm, and the Clark level was IV. Chest computed tomography (CT), abdominal ultrasonography (US), and bone scintigraphy were all negative for metastases, and the tumor was characterized as a T4 N0 M0 tumor (stage II). In December 2000, recurrence of a right axillary lymph node required axillary dissection, and additional treatment with interferon was started in January 2001. In September 2001, a local recurrence appeared close to the primary tumor site and was excised. The work-up for metastases (abdominal US, cerebral CT, thoracoabdominopelvic CT, bone scintigraphy) was still negative.
The patient returned in March 2002 with numerous subcutaneous nodules and a supraventricular tachycardia of 150 beats per minute. The patient was hospitalized for evaluation and biochemotherapy. At that time, transthoracic echocardiography and cardiac magnetic resonance (MR) imaging were performed. Ten days after admission, the patient went into cardiorespiratory arrest, most likely due to cardiac arrhythmia, and died.
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Imaging Findings
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Transthoracic echocardiography showed an irregular mass occupying the apical portion of the left ventricle without obstructing the inflow and outflow tracts (Fig 1). Decreased left-sided cardiac function and pericardial effusion were noted. Cardiac MR imaging with axial turbo spin-echo T1-weighted, fat-saturated turbo spin-echo T2-weighted, and gadolinium-enhanced fat-saturated turbo spin-echo T1-weighted sequences demonstrated a contrast material–enhanced intramyocardial mass in the left apex that protruded into but did not obstruct the ventricular cavity. In addition, the free wall of the left ventricle and a portion of the interventricular septum had an irregular, heterogeneous, thickened appearance (Fig 2). Pleural and pericardial effusions as well as numerous subcutaneous lesions in the chest wall were also present. Contrast-enhanced CT demonstrated mediastinal adenopathy and numerous nodular pulmonary lesions, findings that suggested the presence of metastases.
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Figure 1. US image (apical four-chamber view) shows an irregular mass (arrowhead) within the middle to apical portion of the left ventricle. Mild to moderate pericardial effusion is noted lateral to the left ventricle.
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Figure 2a. Axial unenhanced T1-weighted (a), fat-saturated T2-weighted (b), and contrast-enhanced T1-weighted (c) MR images show an intramyocardial mass (short straight arrow) arising from the apex of the left ventricle. The free wall of the left ventricle and a portion of the interventricular septum have an irregular, heterogeneous appearance. Pleural (long straight arrow) and pericardial (curved arrow) effusions and numerous subcutaneous lesions of the chest wall (arrowheads) are also seen. Note the intense enhancement of the mass, free wall of the left ventricle, interventricular septum, and chest wall lesions in c.
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Figure 2b. Axial unenhanced T1-weighted (a), fat-saturated T2-weighted (b), and contrast-enhanced T1-weighted (c) MR images show an intramyocardial mass (short straight arrow) arising from the apex of the left ventricle. The free wall of the left ventricle and a portion of the interventricular septum have an irregular, heterogeneous appearance. Pleural (long straight arrow) and pericardial (curved arrow) effusions and numerous subcutaneous lesions of the chest wall (arrowheads) are also seen. Note the intense enhancement of the mass, free wall of the left ventricle, interventricular septum, and chest wall lesions in c.
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Figure 2c. Axial unenhanced T1-weighted (a), fat-saturated T2-weighted (b), and contrast-enhanced T1-weighted (c) MR images show an intramyocardial mass (short straight arrow) arising from the apex of the left ventricle. The free wall of the left ventricle and a portion of the interventricular septum have an irregular, heterogeneous appearance. Pleural (long straight arrow) and pericardial (curved arrow) effusions and numerous subcutaneous lesions of the chest wall (arrowheads) are also seen. Note the intense enhancement of the mass, free wall of the left ventricle, interventricular septum, and chest wall lesions in c.
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Pathologic Evaluation
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The results of necropsy confirmed the clinical diagnosis of a widely disseminated metastatic melanoma diffusely involving most organs, including the heart, lungs, brain, meninges, liver, kidneys, spleen, breast, ovaries (Krükenberg-like), skin, serosal membranes, and blood vessels. The metastases varied in size from microscopic to more than 8 cm in diameter (mean, 1 cm). They often had a "miliary carcinomatosis" distribution and were grayish-brown to black.
The heart weighed 441.7 g (normal, 210.5–249.7 g), and the atria and ventricles were enlarged. The adventitia of the great vessels was studded with metastases, but the lumina were normal. Numerous subendocardial and myocardial metastases were diffusely present (Fig 3); a few metastases were subepicardial and pericardial or transmural with epicardial extension, accounting for a pericardial effusion (230 mL). A partially necrotic, obstructive exophytic metastasis measuring 4 x 3 x 2 cm was present in the left ventricle (Fig 4). Papillary muscles appeared to be sites of metastatic predilection from which sessile polypoid tumor nodules originated, the largest of which was found in the right ventricular cavity and measured 1.5 cm.
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Figure 3. Photograph of the gross specimen demonstrates portions of the right atrium (top) and right ventricular septum, both of which are studded with subendocardial tumorlets, some of which are polypoid. The tumorlets range from tan to dark brown and black. Intramyocardial tumor nodules are also seen, but the tricuspid valve (arrow) is tumor free.
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Figure 4. Low-power photomicrograph (original magnification, x25; hematoxylin-phloxin-saffron [HPS] stain) of the left ventricle shows two large, exophytic, extensively necrotic subendocardial metastases (long arrows) obstructing the ventricular cavity (*). In addition, three smaller metastases are seen within the myocardium (short arrows).
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Most of the cardiac metastases were relatively small, measuring a fraction of a millimeter to less than 5 mm. At histologic analysis, these metastases were extensive and nodular and constituted approximately one-half of the "myocardium." The heart-tumor interface was generally sprinkled with a few lymphocytes, without any other stromal reaction being elicited. Most of the larger metastatic nodules showed central necrosis. Cytologic analysis revealed moderate nuclear pleomorphism; a coarse chromatin; focal, moderately prominent acidophilic nucleoli; and brisk mitotic activity, with up to five mitotic figures per high-power field (x400). The cytoplasm was generally moderately abundant, acidophilic, and finely granular with sparse melanin (Fig 5). Intracytoplasmic melanin was demonstrated with Fontana staining, and immunohistologic assays showed that the tumor cells expressed HMB45, a finding that confirmed the melanocytic nature of the cells.
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Figure 5. High-power photomicrograph (original magnification, x400; HPS stain) shows a metastatic nodule (arrow) with moderate nuclear pleomorphism, coarse chromatin, and, in some cells, a prominent acidophilic nucleolus. Most cells contain a large amount of cytoplasm, which is finely granular, acidophilic, and, occasionally, vacuolated. Numerous focal mitoses (not shown) were also seen.
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Discussion
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Epidemiologic Features
Cardiac metastases are far more common than primary involvement, with an estimated ratio of 30:1 (1,2). In the presence of a malignant tumor, cardiac metastases are found in 9.7%–10.7% of cases (3–5). The tumors that most frequently metastasize to the heart and pericardium are lung and breast cancers, melanomas, and lymphomas (5).
The prognosis for melanoma is poor, since this tumor tends to metastasize early. Approximately 30% of patients develop metastatic disease that requires systemic therapy (6). The most common metastatic sites are the lungs, liver, brain, and bones. Cardiac involvement is rarely identified antemortem (<2% of patients) but is found in over 50% of patients at autopsy (5,7). In fact, melanomas have the highest prevalence of cardiac metastases per 100 cases of any neoplasm (8).
Location of Cardiac Neoplasms and Pathways of Spread
All cardiac structures (endocardium, myocardium, epicardium) can be invaded, although the epicardium remains the site most often affected by metastases (1,5). The left ventricular free wall and the ventricular septum—the portions of the heart with the greatest myocardial mass—are the most common sites for myocardial lesions (9). Endocardial metastases manifest as intracavitary lesions. They can block inflow into the heart or outflow from a ventricular cavity and can be the cause of embolisms (9).
The four pathways of cardiac invasion are retrograde lymphatic extension, hematogenous spread, direct contiguous extension, and transvenous extension (10). Generally, a melanoma is disseminated by means of hematogenous spread to the myocardium and epicardium via the coronary arteries or, less frequently, from the vena cavae (11). Because microcirculation in the lungs and liver filters out most of the cancerous cells, these cells rarely reach the coronary arteries. Thus, hematogenous metastases to the heart and pericardium are often associated with hematogenous metastases to other organs (7).
Clinical Features
Although cardiac metastases from melanoma are frequently found at autopsy, they are rarely diagnosed because most patients (90%) are asymptomatic (8). When present, the clinical signs and symptoms of cardiac metastases are nonspecific and include fatigue, superior vena cava syndrome or congestive heart failure, cardiac arrhythmia, pericardial effusion, obstructed right ventricular inflow or outflow, and transient ischemic attack (12).
Arrhythmia remains the most common clinical sign of cardiac metastases (13), and its sudden appearance raises the possibility of cardiac metastatic involvement.
Tumor involvement and its consequences (cardiac tamponade, congestive heart failure, coronary artery invasion, sinoatrial node invasion) are the cause of death in one-third of patients with cardiac metastases (14).
Imaging Features
Because of its easy availability, transthoracic US is the most frequently used imaging modality for screening for cardiac metastases.
Many studies have demonstrated the effectiveness of MR imaging in detecting the presence and defining the anatomy of cardiac and pericardiac masses. Cardiac tumors typically have low signal intensity on T1-weighted images and higher signal intensity on T2-weighted images (15). After contrast material infusion, almost all malignant diseases enhance at MR imaging (16). Melanoma metastases have a characteristic signal intensity at MR imaging (ie, hyperintensity on both T1- and T2-weighted images). However, in intracranial melanotic melanoma, this specific MR imaging pattern is rarely found (17).
Differential Diagnosis
Thickening or nodulation of cardiac structures cannot be considered as a specific clinical sign of metastatic involvement, since it can be the result of any disease process (7). However, because most patients who develop cardiac metastatic involvement already have disseminated extracardiac involvement, recognition of the process is not a problem. Consequently, the diagnosis is not as straightforward when the cardiac involvement is isolated. Cardiac tumors are extremely rare. Rhabdomyomas are the most common cardiac tumors in pediatric patients (18); they are generally found in tuberous sclerosis and often regress with age. Accordingly, cardiac MR imaging is clinically indicated to differentiate between a cardiac tumor and an intracardiac thrombus. Generally, thrombi are located in the posterolateral wall of the left atrium or within the auricular appendage. The hypokinetic apex is prone to the development of a left ventricular thrombus in patients with a history of myocardial infarction (19). At MR imaging, the signal intensity of a thrombus can vary with the age of the thrombus (20). A fresh thrombus will have increased signal intensity on T1-weighted images and bright signal intensity on T2-weighted images, whereas a tumor will have moderate to weak signal intensity on T1-weighted images (19). Older thrombi tend to simulate the characteristic signal intensity of intracardiac tumors (ie, hypointensity on both T1- and T2-weighted images) (19). Cine MR imaging is the most useful in distinguishing between tumors and thrombi. Thrombi demonstrate lower signal intensity than do intracavitary neoplasms at cine MR imaging because of its greater magnetic susceptibility (19). Infusion of gadolinium-based contrast material will also allow differentiation between tumors and intracavitary thrombi, although making this distinction may prove more difficult in the presence of an old thrombus (20).
Treatment
There are few therapeutic options for most patients with cardiac metastases because of the diffuse metastatic involvement and the limited benefit of biochemotherapy. However, for a minority of patients (eg, with isolated cardiac involvement or cardiac function compromised by a tumor), surgery may be an option, assuming that the surgical risk and the survival benefit have been taken into account.
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Conclusions
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Cardiac metastases are common and, in cases of melanoma, may have specific MR imaging characteristics. Although melanoma may not be the most common cause of cardiac metastases, it does metastasize to the heart more frequently than any other primary tumor.
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Acknowledgments
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We thank Claude Grenier for his valuable assistance during the autopsy.
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References
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History
Imaging Findings
