Very large left atrial myxoma: an unusual differential diagnosis of bronchial hyper-reactivity

Introduction

Intra- and paracardiac tumors are rare (incidence in autopsies ca. 0.06%), whereas secondary manifestations of extracardiac masses are more frequent (incidence in autopsies ca. 1.2%) (1). With the exception of paraganglioma, clinical symptoms are typically secondary to mechanical effects of the mass (2).

Case report

A 53-year-old female (body mass index 21.3, body surface area 1.63 m²) had been suffering from occasional dyspnea, atypical angina pectoris, and a decrease in performance. Her primary care physician had initiated treatment for suspected recurrent lower airway infections. This suspicion was supported by a positive methacholine challenge, which was ordered by the consulting pulmonologist and suggested bronchial hyper-reactivity. Subsequently a chest X-ray showed left-atrial enlargment and a questionable mass (Figure 1A). This was confirmed by an echocardiogram ordered by the consulting cardiologist demonstrating a large tumor filling almost the entire left atrium. The mass intermittently prolapsed through the mitral valve orifice. The following transesophageal echocardiography confirmed a combined mitral valve defect (medium transvalvular gradient 11 mmHg and an excentric regurgitation °II. The latter also identified the tumors origin from the interatrial septum (Figure 1B). The added cardiovascular magnetic resonance (CMR) demonstrated a well vascularized mass measuring 67 mm × 46 mm suggesting a myxoma in its typical location (Figure 1C). Finally, pre-operatively performed invasive coronary angiography excluded coronary artery disease and confirmed the tumor by its vascular ‘blush’ supplied by the proximal and distal circumflex coronary artery (Figure 1D). Hemodynamic measurements demonstrated a significantly increased v-wave (48 mmHg) supporting the imaging findings of significant mitral stenosis (Figure E).

Figure 1 The figure reflects the main steps of the diagnostic work-up which lead to the diagnosis left atrial myxoma. (A) Chest X-ray (ap) showing an unclear contour (arrows) suggesting an atrial mass; (B) Transesophageal echocardiography (°124) demonstrating a large TU prolapsing into the mitral valve causing combined mitral valve defect °II; (C) CMR showing the vascularized TU nearly filling out the entire LA; (D) Invasive coronary angiography (RAO 26° cranial 23°) showing blush (circle) marking the TU vasculature supplied by vessels coming off the proximal and distal CX; (E) Hemodynamics (pulmonary capillary wedge pressure) revealed a high v-wave resulting from relevant functional mitral valve stenosis; (F) Intra-operative view into the left atrium showing the large tumor taken out; (G) Histology demonstrating typical findings of myxoma. (HE 20×). Ao, aorta; CX, Circumflex; LA, Left atrium; LAD, left anterior descending; LV, Left ventricle; RAO, right anterior oblique; TU tumor.

Because of the risk of intermittent mitral valve obstruction, and thrombembolism (3), the mass was resected within two days (Figure 1F) and histologically classified as myxoma (Figure 1G). Ten days after cardiac surgery the patient suffered from third-degree atrioventricular block requiring pacemaker implantation.

Conclusions

Even a very large left-atrial tumor causing intermittent, partial obstruction of the mitral valve, may initially present with mild unspecific symptoms. Delayed diagnosis may increase the risk of complications, including frequently associated thromboembolism.

Acknowledgements

Disclosure: The authors declare no conflict of interest.

References

1. Lam KY, Dickens P, Chan AC. Tumors of the heart. A 20-year experience with a review of 12,485 consecutive autopsies. Arch Pathol Lab Med 1993;117:1027-31. [PubMed]
2. Lamba G, Frishman WH. Cardiac and pericardial tumors. Cardiol Rev 2012;20:237-52. [PubMed]
3. Engberding R, Daniel WG, Erbel R, et al. Diagnosis of heart tumours by transoesophageal echocardiography: a multicentre study in 154 patients. European Cooperative Study Group. Eur Heart J 1993;14:1223-8. [PubMed]