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Case 2 - Low Back Pain 

Case History

Low back pain for last 2 years with morning stiffness in a 32 year old Man. He had a blood test in the past which confirmed that he was HLA B27 positive. On examination, he has stiffness with figure of 4 test. Hip joint movements were good. An X-ray of his pelvis with both hips showed fused SI joints. With this, the writing on the wall was clear that he has had Ankylosing spondylitis. He was prescribed Hydroxychloroquine and exercises.


He comes back for a review 4 weeks later. In this time frame, he has stopped HCQs due to urinary incontinence. He was given a course of antibiotic by his GP. He had been to a rheumatologist, who has run the battery of tests for all the inflammatory conditions. Of this, CRP was 186 and ESR was 39. He was then referred to an Infection Specialist. The Blood culture was negative. Patient was not followed up further. Three weeks later, patient presents to our clinic second time for the non resolution of symptoms, mild occasional fever and low back pain. His urinary symptoms have resolved by now.     

Working Diagnosis

Based on clinical findings so far what would be your working diagnosis?

Ankylosing spondylitis?

Inflammatory Arthropathy?


Viral Infection?

Mental Math (History)


Ankylosing spondylitis or any other inflammatory arthropathy are known to cause the raise in CRP and ESR, however it is very unlikely to raise the CRP to this level. Usual pattern is for ESR to be high and CRP marginally raised. UTI can potentially cause high CRP. However for the CRP to be raised to this level it must be a septicemia (blood stream infection). Viral infection rarely causes CRP to raise to this level. 

Clinical Examination

On examination, his vitals are all normal. He is systemically well. His back and hip examination reveals nothing different in comparison to previous examination. 

Working Diagnosis


Based on the clinical history and examination what is your working diagnosis now?




Mental Math (History + Clinical Examination)

Septecemia is less likely now as vitals are stable and for 3 weeks there has been no deterioration and no further symptoms. Tuberculosis is a possibility, however that again would lead to high ESR but less elevated CRP. Malignancy although rare, cannot rule out as of now. 


Blood tests were repeated and CRP was 176 and ESR was 45.

Mental Math (History + Clinical Examination+ Investigations)

Putting all these things together in a nutshell now. There is very high level of CRP which is persistent for 3 weeks now. However this is in the absence of any fulminant signs of septicemia. The zig saw is not fitting together. 

Hence a PET scan was requested. PET scan revealed the mediastinal lymphoma. 

Learning Points

  • CRP & ESR levels can give a huge amount of informations.

  • CRP levels over and above 150 are very rare in any inflammatory arthritis

  • If CRP levels are that high, patient is likely to be having septicemia and be systemically unwell if it is infection.

  • Although, rare diagnosis need to be made rarely, keeping a watchful eye for unusual presentations is important. 

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