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Paper text:
cardiac myxomas are the most common benign cardiac tumour usually found in the left atrium .
they usually present with at least one of the classical triad of obstructive cardiac , embolic and constitutional symptoms . due to their position in the left atrium ,
the most common presentation is with mitral valve obstruction and cardiac symptoms , such as dizziness , dyspnoea that may improve on recumbency , cough , pulmonary oedema and congestive cardiac failure .
myxomas are also commonly associated with embolization of arteries in the central nervous system , kidney and extremities .
constitutional symptoms such as fever , anorexia , weight loss , malaise , myalgia and arthralgia are also frequent .
we describe an unusual presentation of atrial myxoma with microscopic haematuria and significant non - nephrotic - range proteinuria .
a 54-year - old man was found to have microscopic haematuria and proteinuria on two consecutive urine tests as part of routine surveillance for hypertension . the patient had past medical history of essential hypertension and gout .
his regular medications were amlodipine 5 mg once daily and allopurinol 100 mg once daily . on his first nephrological assessment , he was well with no specific complaints .
urinalysis confirmed microscopic haematuria with 25 erythrocytes per millilitre ( siemens diagnostics clinitek multistix ) .
urinary protein - to - creatinine ratio ( pcr ) at referral and on repeat testing in clinic were elevated at 127.3 and 104.8 mg / mmol , respectively .
mol / l and the estimated glomerular filtration rate was 69 ml / min/1.73 m using the modification of diet in renal disease equation .
an electrocardiogram showed voltage criteria for left ventricular hypertrophy and an echocardiogram was therefore arranged to assess end organ damage caused by hypertension .
echocardiography revealed a mobile mass in the left atrium , measuring 5  2 cm in size and attached to the atrial septum ( figure 1 ) .
the mass prolapsed through the mitral valve during systole but did not cause any significant haemodynamic compromise .
parasternal long axis ( four chamber ) view of echocardiogram , showing a mobile mass in the left atrium attached to the atrial septum .
the patient was admitted as an emergency and transferred to a local cardiothoracic centre , where a gelatinous mass was removed during an uneventful operation and shown to be a benign myxoma with small groups of basophilic tumour cells in a stroma of loose , partially haemorrhagic connective tissue .
follow - up after the operation showed resolution of the proteinuria that prompted the original referral . on repeat testing 4 months after resection , urinary pcr
the presentation of atrial myxoma with proteinuria and haematuria in the absence of any other clinical signs or symptoms is very unusual . surgical excision of the tumour resulted in complete resolution of the haematuria and proteinuria and therefore a renal biopsy was not justified .
one previous case report by kalra et al . , also described a patient with myxoma presenting with right heart failure and nephrotic range proteinuria with no evidence of intrinsic renal pathology .
as in our case , surgical removal of the myxoma led to resolution of the proteinuria , suggesting that the myxoma may be responsible for such urinary abnormalities .
other recognized causes of proteinuria in patients with cardiac myxomas include membranous nephropathy , amyloidosis , interstitial nephritis   and cryoglobulinaemia .
patients with myxomas have been shown to have detectable antiendothelial cell antibodies ( aeca ) in peripheral circulation .
this heterogeneous group of antibodies has been found in various vasculitic and connective tissue conditions and has a variety of actions , including endothelial cell activation , apoptosis and cytotoxicity .
it is presumed that myxomas cause local activation of the immune system , allowing the production of such autoantibodies by bystander activation . in animal models ,
cardiac myxomas also secrete interleukin-6 ( il-6 ) , which may have a role in the development of renal injury and proteinuria .
il-6 is a pro - inflammatory cytokine , which causes fever , induces the production of acute phase proteins in hepatocytes and promotes differentiation of b cells , as well as activating macrophages , t cells and b cells .
population - based studies in type 1 diabetes have correlated elevated il-6 levels with the development of gross proteinuria . in addition , using a mouse model of lupus nephritis , cash et al .  
the overproduction of il-6 by myxomas is also responsible for the constitutional symptoms that are present in 90% of patients .
common laboratory findings in patients with myxomas include normocytic anaemia , leucocytosis , thrombocytopaenia , low complements , elevated erythrocyte sedimentation rate , acute phase reactants and immunoglobulins .
in addition , patients may have raynaud s phenomenon and skin rashes , such as erythematous or livedoid macules and papules or telangiectasia . as a result of these abnormalities and the prolonged multisystemic symptoms
, cardiac myxomas could imitate connective tissue disease , such as systemic lupus erythematosus and vasculitis such as polyarteritis nodosa .
myxomas , although uncommon , are an important consideration in the differential diagnosis of many renal conditions .
the production of aeca and il-6 by cardiac myxomas may be relevant as these substances have been implicated with the development of renal injury and proteinuria .
myxomas are uncommon primary cardiac tumours , usually affecting the left atrium . 
 we describe an unusual presentation of cardiac myxoma with asymptomatic proteinuria and haematuria . surgical excision of the tumour resulted in complete resolution of the urinary abnormalities 
 . the production of antiendothelial cell antibodies and interleukin-6 by cardiac myxomas may be relevant as these substances have been implicated with the development of renal injury and proteinuria .