A self-diagnosed case of osteoarthritis

Case history

A 70-year-old widowed female presents to her GP with back pain. She wishes to enquire about using a transcutaneous electrical nerve stimulation (TENS) device to manage her symptoms. Eager not to waste the doctor’s time, she has self-diagnosed osteoarthritis. Despite regular paracetamol, her low back pain has gradually worsened since its onset 12 months ago. The pain is persistent, dull and non-radiating. Mobilising makes it worse, whereas lying down relieves it. It has limited her ability to walk into town to meet with friends. She discloses feeling tied all the time, but attributes this to her age. She denies any weight loss, fever, night sweats, saddle anaesthesia, urine retention, faecal incontinence or leg weakness. Her past medical history includes hypertension and a gastric ulcer, for which she takes amlodipine and omeprazole. She has no family history of malignancy, but recounts that her father suffered from osteoarthritis.

Her observations are normal. Examination reveals bilateral paraspinal tenderness and bony tenderness at the fifth lumbar vertebra. Anterior lumbar spinal flexion is limited to 60° and lateral flexion and extension to 20°. Leg power, sensation and reflexes are intact.

The GP expresses their concern about the bony tenderness, which could suggest an osteoporotic fracture or underlying malignancy. Convinced it is just a simple case of osteoarthritis, the patient is reluctant for investigation, but following discussion, agrees to some blood tests and an X-ray. She decides to continue regular paracetamol, take codeine as required and, if ineffective, to consider physiotherapy, stronger opiates or a TENS device.

Blood tests reveal an erythrocyte sedimentation rate (ESR) of 84, with serum protein electrophoresis identifying a high monoclonal immunoglobulin (Ig) A protein of 2.1 g/dl. An X-ray of the lumbar spine shows lytic lesions. The patient is urgently referred to haematology for further investigation. A skeletal survey shows further lytic lesions in the left femur, while a bone marrow biopsy reveals plasma cells constituting over 40% of the total bone marrow cell count, consistent with a diagnosis of multiple myeloma. She is commenced on chemotherapy and actively monitored by haematology.

Discussion

Multiple myeloma is a cancer of plasma cells that accounts for approximately 10% of all haematological malignancies (Smith & Yong, 2013). Over 4700 cases are diagnosed annually in the UK, with a median age at diagnosis of between 65 and 70 years (Cancer Research UK, 2015). Presenting symptoms and signs can vary, with a third of all cases being diagnosed after an incidental finding of a raised ESR or immunoglobulins (Smith & Yong, 2013). Bone marrow infiltration can lead patients to present with pain, fractures, spinal cord or nerve root compression and symptoms of hypercalcaemia, while bone marrow failure can result in anaemia and lethargy, recurrent bacterial infections and easy bruising or bleeding. Excess monoclonal antibodies can cause renal impairment, in addition to hyperviscosity, which increases the risk of cerebrovascular events (Smith & Yong, 2013).

In the case study, the patient's history of fatigue and the presence of bony tenderness on examination raised a suspicion of myeloma. When suspected, tests for myeloma should include a full blood count, renal function, bone profile, ESR, immunoglobulins (IgG, IgA, IgM) and serum protein electrophoresis. Urine should be analysed for Bence–Jones protein, or alternatively serum-free light chains quantified. X-rays should also be performed of symptomatic areas. Findings suggestive of myeloma would include a raised ESR, anaemia, renal impairment, hypercalcaemia, detection of serum or urine paraprotein, and lytic lesions on X-ray. In this situation, urgent referral to haematology would be indicated (Smith & Yong, 2013).

Differential diagnoses include chronic lymphocytic leukaemia, B-Cell non-Hodgkin’s lymphoma, solitary plasmacytoma and monoclonal gammopathy of undetermined significance (MGUS), an asymptomatic phase of monoclonal antibody secretion that precedes myeloma (Nau & Lewis, 2008).

Myeloma is an incurable disease, so treatment aims to prolong and maximise quality of life. Relatively fit patients can be offered chemotherapy and stem cell transplantation. When this is unsuitable, options include biological therapies combined with an alkylating agent or corticosteroid. GPs have a role in monitoring for complications. Patients may become anaemic or develop infections, while emergency admission may be indicated if they develop an acute kidney injury, hypercalcaemia or signs of spinal cord compression. Orthopaedic input may be required for pathological fractures, while GPs may also liaise with secondary care to discuss the treatment of bone pain with radiotherapy or bisphosphonates (Smith & Yong, 2013). Although myeloma is incurable, half of patients in England and Wales survive for at least 5 years, with a third surviving beyond 10 years (Cancer Research UK, 2015).

This case study highlights the need to challenge patients’ perceived diagnoses and to maintain a high index of suspicion for myeloma. GPs have an integral role in the diagnosis, recognition of complications, management of pain and ultimately end-of-life care.