CASE REPORT

We report on a 70 year old female patient who was admitted to hospital with a diagnosis of two isolated hepatic metastases originating from colorectal cancer. A left sided hemicolectomy had been performed one year earlier because of mechanical bowel obstruction caused by a sigma carcinoma without the presence of distant metastases. Surgery was followed by adjuvant chemotherapy with 5–fluorouracil and leucovorin.

At presentation the patient appeared to be in excellent health with no major complaints. On physical examination, the patient was afebrile, normotensive, and had a regular pulse rate without orthostatic changes. Cardiovascular examination revealed a high grade protosystolic murmur at the apex radiating into the axilla. No jugular venous distension was observed. The findings on abdominal and pulmonary examination were unremarkable and a detailed neurological examination gave normal results. During the staging procedures, a 10 × 3 cm tumour mass was identified in the left atrium by computer tomography (fig 1). Echocardiography studies demonstrated a partly cystic tumour mass with attachment at the posterior left atrial wall (fig 2) and showed a diastolic prolapse into the mid-left ventricular cavum (fig 3). The inter-atrial septum and the left atrial auriculum were free of any tumour mass. A pericardial effusion was not detected. The antegrade mitral flow was unaffected with no sign of obstruction; however, a moderate mitral regurgitation with secondary pulmonary hypertension was affected because of an impediment of co-adaptation of the mitral leaflets by the tumour. Although there was almost complete occupation of the left atrium by the tumour mass, the patient was still in sinus rhythm without any history of rhythm disturbances. After uneventful resection of the tumour (fig 4), histological analysis of the mass revealed abundant myxomatous stroma, which is characteristic of myxoma, adjacent to normal myocardium.¹

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Figure 1

Computed tomographic scan of the thorax showing a space occupying mass (*) attached to the posterolateral wall of the left atrium, prolapsing into the left ventricular cavum (†).

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Figure 2

Echocardiogram showing same details as in fig 1; although the left atrium is almost completely occupied by the myxoma, the patient is still in sinus rhythm (arrowheads).

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Figure 3

Further echocardiogram showing diastolic prolapse into the mid-left ventricular cavum, the patient remaining in sinus rhythm all the time.

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Figure 4

Macroscopic aspect of the resected mass.

DISCUSSION

The present case demonstrates some interesting features. Firstly, the usual site of attachment of a myxoma is in the area of the fossa ovalis. It is rare to find a myxoma attached at the posterior left atrial wall and this raised suspicion of malignancy, especially as the patient had an underlying metastatic disease. Furthermore, various clinical signs and symptoms produced by cardiac myxomas have been reported in the literature; however, asymptomatic giant cardiac myxomas of the left atrium, as described in this patient, are very rare. In the US Armed Forces Institute of Pathology series only 16 of 130 patients with left and right heart myxomas were asymptomatic and myxomas were detected incidentally.² The patient described here was still in sinus rhythm although an atrial distension caused by mitral regurgitation was detected. Taken together, asymptomatic giant left atrial myxomas are very rare, they can attach at atypical locations, and in such cases underlying malignancy should be considered.