Metastatic Extracavitary Cardiac Melanoma
The Role of Contemporary Imaging Techniques in Diagnosis and Surgical Planning
Melanoma is a neoplasm notorious for its dismal prognosis and its propensity for cardiac involvement. Roughly a third of patients diagnosed with primary cutaneous melanoma develop pulmonary, osseous, cerebral or hepatic metastatic disease ante mortem. In contrast, ante mortem cardiac involvement is reported in 2% of cases but in over 50% of patients with metastatic melanoma postmortem.1 Cardiac involvement is usually multifocal, believed to disseminate hematogenously and commonly involves the epicardium, myocardium, pericardium or may present as intracavitary tumors.2
The surgical management of cardiac tumors can be challenging, particularly when they occur in locations that make surgical access and resection technically difficult. Recent refinements in myocardial perfusion imaging, computerized tomography, and cardiac magnetic resonance imaging help provide precise information on anatomic location, vascularity, and tumor extension into adjacent mediastinal structures.3 Early detection of cardiac melanoma has important therapeutic and prognostic implications.
We describe an asymptomatic patient with malignant melanoma and solitary extracavitary, cardiac metastasis diagnosed ante mortem. Multiple imaging modalities provided the surgeon with crucial information leading to successful tumor resection facilitating further medical management.
A 56-year-old white male with a past medical history significant for migraine, hypertension and hyperlipidemia was noted to have a bleeding pigmented lesion on his left upper back. Excisional biopsy of the pigmented lesion was performed and on histopathology was reported as a Clark level IV ulcerated melanoma. A month later, a second pigmented raised lesion appeared in the vicinity of the previous lesion; it was excised with a 2.0 cm margin and a sentinel lymph node. Histopathology disclosed malignant melanoma with involvement of the sentinel node. He underwent multimodality imaging as part of a metastatic workup. Positron emission tomography scanning with fluorine 18 fluorodeoxyglucose revealed a mediastinal mass with intense metabolic activity, measuring 3.0 cm and a maximum standardized uptake value of 11.4 (Figure 1). Transesophageal echocardiography performed to further characterize this finding showed a well circumscribed mass of homogenous echotexture interposed between the posterior aortic wall (behind the noncoronary and left coronary sinuses of Valsalva) and the left atrium (Movie I). It appeared vascular on color Doppler flow (Movie II; Figure 2A, arrow), and no luminal invasion of adjacent chambers, superior vena cava or right pulmonary artery was apparent. Real time myocardial contrast-enhanced imaging (“power modulation imaging,” Phillips Medical Systems, Eindhoven, the Netherlands) with Definity confirmed prominent vascularity of the mass (Figures 2A and 2B). On cardiac catheterization, intense tumor blush was evident; the mass appeared to be perfused by branches of the right and circumflex coronary arteries (Figures 3A and 3B). Computed tomography angiography was performed to define the size and extent of this cardiac mass in anticipation of surgery. It measured 31×31 mm axially, 27.9×32.1 mm coronally, and 33.1×28.2 mm sagittally (Figure 4). Our patient successfully underwent thoracotomy and tumor resection under cardiopulmonary bypass. Gross pathological examination of the excised cardiac mass showed a pink-tan soft tissue specimen. Histological analysis of the mass by hematoxylin and eosin staining (Figure 5) revealed melanoma cells with large nuclei and prominent nucleoli. Immunohistochemical staining for melanoma-associated tumor markers S-100 (Figure 6A) and MART-1 (Melanoma Antigen) recognized by T cells (Figure 6B) are also shown. Our patient tolerated the procedure well but developed transient atrial fibrillation postoperatively. The rest of his stay was otherwise uneventful and he was discharged home in stable condition.
The online-only Data Supplement, which contains Movies I and II, can be found at http://circ.ahajournals.org/cgi/content/full/115/16/e415/DC1.