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A 68-year-old man presented with a history of low-grade, continuous fever and malaise for 3 years. There was no associated history of cough, breathlessness, palpitations, headache, vomiting, joint pains, rash, urinary or bowel disturbances. The patient had been investigated on many occasions in the past for the fever. The investigations, including haemoglobin, blood counts, peripheral smear examination, kidney and liver functions tests, chest X-ray and ultrasonography of the abdomen, were all normal. The only abnormality detected was a persistently elevated erythrocyte sedimentation rate (ESR) of between 65 and 130 mm in the first hour. The patient had received several courses of antibiotics and was currently receiving antitubercular drugs prescribed empirically by a practitioner.
Examination revealed a conscious, febrile male with pulse 100 beats/min regular, and blood pressure 130/70 mmHg. The respiratory, cardiovascular, abdominal and neurological examination was unremarkable. The laboratory investigations of the patient are summarised in the table. A magnetic resonance imaging (MRI) scan of the thorax is shown in the figure.
- What is your provisional diagnosis?
- How would you investigate the patient further?
- Describe the MRI findings.
- What is your final diagnosis?
Fever of unknown origin (FUO). By definition,1 FUO consists of:
fever higher than 38.3°C (101°F) on several occasions
a duration of more than three weeks, and
failure to reach a diagnosis after 1 week of in-patient investigations.
FUO is one of the most frequently encountered clinical situations. Keen observation, patience and a diligent diagnostic work-up are mandatory for evaluating the cause of FUO. The major causes of FUO are listed in box FB1. Of these, infections are still the leading cause, followed by neoplasms. With increasing duration of fever, the likelihood of an infectious aetiology diminishes and the other causes become more important.
Since the initial evaluation for the cause of fever was non-contributory, the further diagnostic work-up should include bone marrow aspiration/biopsy, liver biopsy, echocardiography and computed tomography or MRI of the chest and abdomen. Most causes of FUO can be detected after this screening. In our patient, the bone marrow aspiration revealed a normoblastic marrow with a myeloid to erythroid ratio 2:1. There was an increase in the plasma cells to 10–15% and megakaryopoiesis was normal.
The MRI scan of the thorax reveals a 5.2 × 3.6 cm mass arising from the interatrial septum on the left side in the region of the fossa ovalis and extending to the left ventricle, suggestive of a left atrial mass (? myxoma)
The patient successfully underwent tumour excision by a biatrial approach under cardiopulmonary bypass and histopathology confirmed the diagnosis of an atrial myxoma.
Primary cardiac tumours are rare and are observed in 0.0017% to 0.28% of all autopsies.2 Atrial myxomas constitute 50–90% of these3 4 and 75% of the atrial myxomas have a left atrial origin. The tumours are considered to be benign by most, and recent evidence suggests that they may originate from the endocardial sensory nerve tissue.5
Atrial myxomas remain asymptomatic for varying periods before they manifest with classic features (box FB2). Most tumours present with dyspnoea, chest pain, and fatigue; a third heart sound, tumour plop and a diastolic murmur are prominent auscultatory findings.4Constitutional symptoms occur frequently, although it is rare for a cardiac myxoma to present as FUO alone, without any symptoms or signs referable to the cardiovascular system, as in this case. In two large series of 366 patients with FUO, an atrial myxoma was detected in only two patients.6 7 Many associated conditions coexist with atrial myxomas, especially with the familial types (boxFB3).8
Anaemia, leucocytosis and a raised ESR are usual, and cardiomegaly may be evident on a chest X-ray in some patients. Echocardiography is mandatory for the diagnosis of atrial myxomas and the transoesophageal route is superior to the transthoracic route in the identification of atrial masses.9 Recently, MRI has been shown to delineate the nature and extent of cardiac myxomas very well.10
Surgical excision is advisable for all atrial myxomas, even asymptomatic ones, as embolisation may have drastic results, and can even lead to sudden cardiac death. Recurrence of atrial myxomas after an initial excision is well known and is thought to represent an incomplete resection. The present case was unusual in that the atrial myxoma produced nosymptoms and signs other than a prolonged fever.
Left atrial myxoma.