Rare Case of Cardiac Metastasis in a Patient with Cutaneous Squamous Cell Carcinoma of Foot Detected on ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography–Computed Tomography

A 50-year-old woman presented to our department with a large fungating mass lesion involving the right foot region. Contrast-enhanced magnetic resonance imaging of right foot showed ill-defined heterogeneous mass involving skin, subcutaneous tissue of the heal region with associated focal erosion of posterior-inferior cortex of right calcaneum. Computed tomography (CT) abdomen pelvis showed right inguinal lymphadenopathy, following which the patient underwent right below knee amputation. As part of restaging workup, ¹⁸F-fluorodeoxyglucose positron emission tomography–computed tomography (FDG PET-CT) study was done, which showed FDG avid hypodense lesion involving the interventricular septum (IVS) adjacent to inferior wall of heart [Figure 1a showing MIP with black arrow; Figure 1f-i showing fused PET-CT and CT images, respectively] suggesting cardiac metastases. In addition to this, there were metastases involving right inguinal [Figure 1b and c showing PET-CT fused and CT images, respectively], right pelvic, prevascular lymph nodes [Figure 1d and e showing PET-CT fused and CT images, respectively], bilateral lungs, and left scapula. For confirmation of the cardiac metastasis and as a part of baseline cardiac evaluation, two-dimensional echocardiography was done, which showed an ill-defined echogenic lesion involving the IVS and apex, measuring approximately 3.3 cm × 3.0 cm, with normal ejection fraction of 60% and no significant regional wall motion abnormality.

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Figure 1 ¹⁸F-fluorodeoxyglucose avid hypodense lesion involving the interventricular septum adjacent to inferior wall of heart, (a) showing MIP with black arrow and (f-i) showing fused positron emission tomography–computed tomographic and computed tomographic images. ¹⁸F-fluorodeoxyglucose avid metastases involving right inguinal and prevascular lymph nodes, (b-e) showing fused positron emission tomography–computed tomographic and computed tomographic images

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Cardiac metastasis is a rare finding. As the patients are often clinically silent or have nonspecific symptoms, metastases to the heart are difficult to diagnose and usually detected in the postmortem setting during an autopsy. When they present with symptoms, the manifestations include heart failure, arrhythmias, valvular disease, and cardiac tamponade. The most common primary cancers in patients with cardiac metastases include melanoma, mediastinal tumors, lung cancer, breast cancer, and leukemia.[1] Four hypotheses have been believed for cardiac metastases, those include direct extension, hematologic spread, lymphatic spread, and intracavitary diffusion via the inferior vena cava or pulmonary veins.[123] As to primary skin malignancies, there are several reports of metastatic malignant melanoma in the myocardium;[4] however, there are only a few published case reports of metastatic squamous cell carcinoma (SCC) to the heart.[5678] With the increasing use of PET-CT in oncology, asymptomatic cardiac metastases are now getting detected more frequently. Reports of cardiac metastases on PET/CT are seen in melanoma,[9] Ewing's sarcoma,[10] renal cell carcinoma,[11] breast cancer,[12] upper aero-digestive tract,[3] head-and-neck cancer,[13] carcinoma rectum,[14] to name a few, with no reports from cutaneous SCC. Our case is a valuable addition to the existing literature on myocardial metastases and also highlights the role of FDG PET/CT in the detection of such rare sites, especially in asymptomatic patients, which otherwise would have been undiagnosed.