A case of heavy legs

An infrequent attender presented with aching legs, explains Dr David Morris.

Malcolm was a 66-year-old retired bank manager whom I had not seen before - a testament to his good health and his ability to self-manage minor illness.

For the last month or so he had been experiencing heaviness of his legs and aching in particular of his left tibia, symptoms that seemed worse with exercise and notably when climbing stairs. He also had some low back pain.

Malcolm felt tired but had no fever or weight loss. He had no significant past history, and was not taking regular medication.

Examination of the legs did not reveal any swelling of his calves, knees or ankles, and no rashes were to be seen. His hips and knees could be taken painlessly through a full range of movement and I could not detect any local tenderness of his legs or spine. His feet were warm and foot pulses easily palpable; power, tone, reflexes and light touch sensation appeared intact and symmetrical in his legs.

I arranged for an X-ray and a set of bloods and asked Malcolm to return with the results. In the meantime I suggested he use ibuprofen to ease symptoms.

Raised ESR
The most striking result was a raised ESR. Borderline hypercalcaemia was noted but other blood tests were normal, as was an X-ray of his lower left leg.

The combination of raised ESR and elevated calcium suggested myeloma, although further examination found no evidence of lymphadenopathy or hepatosplenomegaly. Ibuprofen had not eased symptoms and so we switched to paracetamol.

A chest X-ray, serum protein electrophoresis and urine for Bence Jones protein were requested. Serum protein electrophoresis revealed an abnormal band in the gamma zone, characterised as an IgM kappa paraprotein. Urgent referral was made to the haematologist, with a provisional diagnosis of myeloma.

A bone-marrow aspirate showed infiltration with lymphocytes and plasma cells and this, together with the IgM paraproteinaemia, made the diagnosis Waldenstrom's macroglobulinaemia.

Waldenstrom's macroglobulinaemia is an uncommon condition, principally affecting patients aged 50-70, and typically progressing insidiously.

It is a paraproteinaemia arising from a single clone of plasma cells, but in this case it produces IgM immunoglobulins.

Renal failure
Hyperviscosity from high levels of paraprotein can produce headaches and visual disturbance and can contribute to an increased risk of thrombosis (or, by interfering with platelet function and coagulation factors, bleeding) and renal failure.

Engorged retinal veins and retinal haemorrhages may be seen. Bone marrow infiltration can lead to anaemia, neutropenia and increased susceptibility to infection, and thombocytopaenia, again increasing risk of haemorrhage. Lymphadenopathy and splenomegaly may be presenting features. Possible systemic sequelae include fatigue, fever, night sweats and weight loss.

Waldenstrom's is essentially an incurable condition.

Outcome
Malcolm's paraprotein level was relatively low at 12g/l and has never subsequently risen beyond 17g/l. He has been managed conservatively with increased fluid intake and daily aspirin.

A lumbar X-ray revealed osteopenia, and Malcolm is taking calcium and vitamin D supplements and weekly alendronate.

The leg symptoms have not progressed and Malcolm uses co-codamol as required. Although tiredness persists, the lifestyle disturbance is small.

I can recall only one other case of Waldenstrom's in the past 10 years, and the presenting feature was again heavy legs. So when a patient reports heavy legs rather vaguely, and vascular and neurological examinations appear normal, it would be wise to include ESR and serum and urine paraproteins in investigations.

Dr Morris is a GP in Shrewsbury, Shropshire.

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