Low Back Pain With GI Complaints: Don't Miss This Diagnosis

Stephen Paget, MD


July 13, 2011

The Clinical Detective Game

There are a few ways to address this type of complex patient:

  1. Profile the illness: This patient's illness is manifested by a 6-month history of fatigue and weight loss, low back pain and morning stiffness for 4 years, decreased range of motion of the entire spine, probable left sacroiliitis, decreased chest expansion, abdominal pain and blood per rectum, anemia, thrombocytosis, and an elevated sedimentation rate and C-reactive protein.

  2. Clinical designations: I would characterize this young man's illness as chronic (back pain began 4 years ago), systemic (involving multiple organ systems including musculoskeletal, bowel, and bone marrow and constitutional symptoms), inflammatory (high sedimentation rate, weight loss), progressive, and functionally limiting. Such labeling is of key importance because the timing, severity, ongoing, and expanding nature of the illness "educates" the differential diagnosis.

  3. Develop a broad and well-thought-out differential diagnosis: The first is to think broadly about the illness. The differential diagnosis of a systemic inflammatory disorder must always initially include infection first because that needs to be addressed and treated immediately, cancer next for the same reason, and then a systemic inflammatory/autoimmune disorder.

  4. Choose sentinel clinical manifestation(s): Sentinel, centrally important, clinical manifestations should jump out at you. These are defining manifestations around which the illness revolves or that are likely central to its pathology. In this patient they are low back pain and stiffness and persistent abdominal pain and blood in the stool.

  5. Defining the "age" of the illness and significance of a given clinical manifestation in the overall picture: One might argue about the "age" of this patient's illness (ie, 1 year vs 4) and whether his bowel problem is NSAID-related gastropathy and not inflammatory in origin. I choose to time his back problem as starting 4 years ago and the bowel approximately 1 year ago. This is key if one is to make a strong argument for an important clinical connection between the two.

The Differential Diagnosis: Employing the clinical framing that arises from 1-5 above:

  1. Infection:

    1. Acute or subacute bacterial or viral infections are unlikely in view of the length of this patient's illness and lack of fever, night sweats, and chills. Salmonella, Shigella, Yersinia, Campylobacter, and Clostridium difficile can lead to abdominal symptoms and a reactive spondyloarthritis with low back/sacroiliac inflammation but the length of this illness makes them unlikely triggers.

    2. Acute/chronic viral infections such as hepatitis B and C, parvovirus, or HIV would be unlikely culprits as the cause of 4 years of low back pain and recent abdominal pains without other viral-related problems. AST and ALT are normal.

    3. Subacute or chronic infectious disorders like tuberculosis or fungal disorders might be considered, if only to rule them out in your mind. But the 4-year horizon and lack of characteristic clinical manifestations rule strongly against these.

    4. Whipple disease due to the actinomycetes-like Tropheryma whippelii bacterium fulfills many of the characteristics of this gentleman's illness in that it can be a chronic, systemic, inflammatory, and progressive illness that can present with bowel, joint, and even back inflammation. However, the lack of malabsorption and diarrhea, adenopathy, fever, and uveitis rule against it.

  2. Cancer: Almost all cancers are unlikely causes of this patient's back and bowel symptoms because of the length of this patient's illness. Metastatic solid cancer, lymphoma, or leukemia can involve the spine and likely lead to abdominal pain with bleeding but not in a stealthy manner over 4 years.

  3. Inflammatory/autoimmune disorders:

    1. Spondyloarthritis related to Crohn disease or ulcerative colitis is a strong possibility, even though the back pain probably predated the bowel symptoms by a few years. However, inflammatory bowel disease can be quite occult and perhaps brought to the fore by the NSAID given for back pain.

    2. Rheumatoid arthritis (RA): Never associated with low back pain or bowel symptoms and the lack of a symmetrical polyarthritis of the small joints of the hands and feet rule this out completely.

    3. Systemic lupus erythematosus (SLE): There is nothing in the case profile that is consistent with SLE or other autoimmune disorders such a scleroderma or dermatomyositis. SLE is associated with an RA-like polyarthritis and not low back pain.

    4. Sarcoidosis: Bowel and low back symptoms are not at all characteristic of sarcoidosis.


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