Clinical course
Electrocardiogram revealed normal sinus rhythm. Echocardiogram in clinic demonstrated normal left ventricular function and a mass in the anterior mid right ventricle (RV) that was concerning for thrombus (Figure 2). He was admitted and started on heparin drip given the echocardiogram findings and concern for pulmonary embolism. An emergent computed tomographic (CT) scan of the chest demonstrated bilateral pulmonary emboli and confirmed the RV thrombus (Figure 3). Doppler of the lower extremity did not reveal any evidence of deep venous thrombosis. His dyspnea improved with intravenous heparin and he was discharged home on subcutaneous low molecular weight heparin given his recent cancer and evidence of thromboembolism while on apixaban. Two months later, a PET-CT scan done for surveillance of his cancer demonstrated intense uptake in RV anterior, free wall and hilar lymph nodes concerning for metastatic cancer (Figure 4). A cardiac MRI for characterization of RV mass (Figure 5) clearly demonstrated 2 masses in the RV wall along with cavitary thrombus. A transbronchial biopsy of hilar lymph nodes was performed which confirmed the diagnosis of metastatic squamous cell carcinoma.
Due to widespread metastases he was deemed inoperable and started on immunotherapy with cemiplimab. Six months after starting immunotherapy, his RV mass appeared smaller in size.
Repeat PET-CT scan showed persistent hypermetabolic uptake in the RV but showed full metabolic resolution of the previously demonstrated hilar lymphadenopathy.
Discussion:
In our case, the patient had curative intent surgery and radiation therapy for local recurrence of SCC and was believed to be in remission. He had rapidly worsening dyspnea and CT findings consistent with pulmonary embolism and it was therefore reasonable to assume that the RV mass was thrombus. However, subsequent PET-CT and Cardiac MRI showed metastatic cancer hiding behind the guise of thrombus. Lung, breast, esophagus and hematologic malignancies are the most common causes of cardiac metastasis1. Cutaneous SCC results from malignant growth of epidermal keratocytes and is one of the most common skin cancers. Local recurrence after curative surgery is uncommon and occurs in < 5%. Cardiac metastases of cutaneous SCC is extremely rare and is usually associated with other non-cardiac metastases.2,3
Mural thrombi in the cardiac cavity can mimic a cardiac mass or mask an underlying tumor. There are a few case studies of RV tumors initially misdiagnosed as RV thrombus especially in the setting of pulmonary embolism. In cases where cMRI was not available, diagnosis was made when there was no response to thrombolytic therapy and surgical thrombectomy was performed.4,5 In other cases, cMRI and/or PET imaging helped disclose underlying malignancy.6,7
While some primary malignancies such as gastric, lung, pancreatic and brain and certain histologic types such as adenocarcinomas carry a high risk for thromboembolism, rates of thromboembolism with cutaneous SCC is low. In one analysis of a large national cohort, the risk of thromboembolism in patients with cSCC was similar to general population.8 Pulmonary embolism or RV mural thrombus in such patients with such low risk for thromboembolism should have therefore raise suspicion for cardiac metastases. Cardiac tumors can cause thromboembolism by 2 mechanisms: thrombus formation overlying the tumor surface and tumor fragmentation.7,9,10
Our case is unique in 2 aspects: 1) metastasis to the heart occurred in the absence of overt other metastases in a patient with cutaneous SCC which has a very low potential for cardiac metastasis and thromboembolism; 2) cardiac metastases was associated with mural thrombus and pulmonary embolism which created a diagnostic difficulty and delay. Our case highlights the importance of suspecting metastatic spread to the heart in such patients with history of malignancy who present with pulmonary embolism and RV abnormalities. Multimodality imaging with cardiac MRI, PET-CT can be of immense value in diagnosing underlying metastatic tumors in patients with ventricular thrombus.
Conclusion: Cardiac metastases should be suspected in individuals with right ventricular thrombi and known history of malignancy. Multimodal imaging with PET-CT and cardiac MRI is essential for timely diagnosis.
References:
  1. Goldberg A, Blankstein R, Padera R. Tumors Metastatic to the Heart. Circulation. 2013;128:1790–1794. https://doi:10.1161/CIRCULATIONAHA.112.000790.
  2. Kondo T, Takahashi M, Kuse A, et al. An autopsy case of right ventricular cardiac metastasis from squamous cell carcinoma of the left hand. Egypt J Forensic Sci. 2016;6:509-512. https://doi.org/10.1016/j.ejfs.2016.05.002
  3. Efendizade A, Kobayashi D, Forbes TJ, Liu S, Lieberman R, Afonso L. Myocardial Metastasis of Cutaneous Squamous Cell Carcinoma in a Burn Patient. CASE (Phila). 2018;3:6-10. https://doi:10.1016/j.case.2018.09.004
  4. Gül M, Babat N, Uçar FM, Kuyumcu MS, Özeke O. Massive pulmonary embolism and a cardiac mass: Thrombus or metastasis? Turk Kardiyol Dern Ars 2016;44:597-599 https://doi: 10.5543/tkda.2016.77772 597
  5. Han GH, Kwon DY, Ulak R, Ki KD, Lee JM, Lee SK. Right ventricular metastatic tumor from a primary carcinoma of uterine cervix: A cause of pulmonary embolism. Obstet Gynecol Sci. 2017;60:129-132. https://doi:10.5468/ogs.2017.60.1.129
  6. Galiuto L, Locorotondo G, Fedele E, et al. Cardiac thrombi mistaken for metastasis in recurrent melanoma. J Cardiovasc Med. 2015;16 Suppl 1:S29-S30. https://doi: 10.2459/JCM.0b013e3283613967
  7. Kalvakuri K, Banga S, Upalakalin N, Shaw C, Davila WF, Mungee S. Metastatic right ventricular mass with intracavitary obliteration. J Community Hosp Intern Med Perspect. 2016;6:31679. https://doi:10.3402/jchimp.v6.31679
  8. Rudy SF, Li K, Moubayed SP, Most SP. Risk of Venous Thromboembolism in Patients With Keratinocyte Carcinoma. JAMA Facial Plast Surg. 2018;20:453-459. https://doi:10.1001/jamafacial.2018.0331
  9. Ma G, Wang D, He Y, Zhang R, Zhou Y, Ying K. Pulmonary embolism as the initial manifestation of right atrial myxoma. Medicine. 2019; 98:e18386 https://doi: 10.1097/MD.0000000000018386
  10. Porres-Aguilar M, DeCicco I, Anaya-Ayala JE, et al. Cardiac metastasis from liposarcoma to the right ventricle complicated by massive pulmonary tumor embolism. Arch Cardiol Mex. 2019;89:279-282. https://doi:10.24875/ACM.M19000036
Figure legend
1: Chronology chart of events prior to presentation
A timeline of patient’s previous medical history before his presentation to the cardiology clinic with unexplained shortness of breath.
2. Right heart thrombus on echocardiography
Image of parasternal long axis of the RV anterior wall with contrast agent showing a non-enhancing mass in the anterior mid right ventricle suggestive of thrombus (red arrow).
RV=Right ventricle; LV=Left ventricle
3. Right heart thrombus on CTA of the chest
A) Computed tomography angiography (CTA) chest with contrast as viewed in coronal section demonstrates a filling defect in the lateral basal-mid right ventricle (red arrow).
B) Computed tomography angiography (CTA) chest with contrast as viewed in transverse section demonstrates a filling defect in the anterior mid right ventricle (red arrow).
RV=Right ventricle; LV=Left ventricle; RA=Right atrium
4. Cardiac metastatic disease seen on PET-CT scan
Positron emission tomography- computed tomography (PET- CT) scan shows two hypermetabolic foci (blue arrows) within the heart corresponding to filling defects identified on previous chest computed tomography angiography (CTA) concerning for cardiac metastatic disease.
RV=Right ventricle; LV=Left ventricle
5. RV masses with thrombus on MRI
High resolution late gadolinium enhancement Magnetic Resonance Imaging (MRI) showing two enhancing masses at the anterior and lateral wall of the mid right ventricle (blue arrows), suspicious for metastatic disease. A non-enhancing mass seen in the adjacent basal-mid right ventricle is a thrombus (red arrow).
RV=Right ventricle; LV=Left ventricle