A 28-year-old man comes to the office with a 2-month history of dull low back pain and morning stiffness. The pain had an insidious onset, and the patient does not recall any recent trauma. He attempted treatment with acetaminophen and spinal manipulation, which did not provide relief. The patient has usually slept on his back but now must lie on his side to fall asleep easily. Past medical history is unremarkable. Vital signs are normal. Physical examination shows limited anterior flexion of the spine. There is no swelling or warmth of any peripheral joints. X-rays reveal narrowing of the sacroiliac joints. Which of the following is most strongly associated with this patient's disease?

Question

A 28-year-old man comes to the office with a 2-month history of dull low back pain and morning stiffness.  The pain had an insidious onset, and the patient does not recall any recent trauma.  He attempted treatment with acetaminophen and spinal manipulation, which did not provide relief.  The patient has usually slept on his back but now must lie on his side to fall asleep easily.  Past medical history is unremarkable.  Vital signs are normal.  Physical examination shows limited anterior flexion of the spine.  There is no swelling or warmth of any peripheral joints.  X-rays reveal narrowing of the sacroiliac joints.  Which of the following is most strongly associated with this patient's disease?

Quizplus · Accepted Answer

Ankylosing spondylitis is a chronic inflammatory disorder of the sacroiliac joints and axial skeleton. It is most common in young and middle-aged men and presents with morning stiffness and low back pain. Ankylosing spondylitis is characterized by destruction of articular cartilage with resulting stiffness and fusion of axial joints. The sacroiliac joints are often tender to palpation, and the spine may have decreased range of motion. X-ray of the sacroiliac joints may reveal erosions, sclerosis, narrowing, and ultimately fusion of the joint spaces. Spine x-rays reveal sclerosis, ligamentous calcification, and vertebral fusion ("bamboo spine"). Ankylosing spondylitis, reactive arthritis, arthritis associated with inflammatory bowel disease, and psoriatic arthritis are seronegative spondyloarthropathies, so-called due to the absence of serum rheumatoid factor. Patients with these diseases have a higher incidence of the human leukocyte antigen (HLA) B27 allele compared to the general population, although most patients with HLA B27 will not develop spondyloarthropathies. (Choice B) Class I HLA proteins (eg, HLA B27) are expressed by all nucleated cells and present endogenous antigens to CD8⁺ cytotoxic T cells. By contrast, HLA class II proteins (eg, DR, DP, DQ alleles) are expressed by antigen-presenting cells (eg, macrophages, dendritic cells) and present predominantly foreign antigens to CD4⁺ helper T cells. Conditions associated with HLA class II genotypes include rheumatoid arthritis, type I diabetes mellitus, and celiac disease. (Choice C) Rheumatoid factor (immunoglobulin [Ig] M antibodies against self IgG) is present in the majority of patients with rheumatoid arthritis and may be seen in a variety of other autoimmune diseases as well as in some healthy individuals. (Choice D) Complement component deficiencies are associated with recurrent infections and systemic lupus erythematosus. (Choice E) IgA deficiency causes recurrent mucosal and respiratory infections and anaphylactic reactions after the transfusion of blood products. Educational objective: The seronegative spondyloarthropathies include ankylosing spondylitis, reactive arthritis, psoriatic arthritis, and arthritis associated with inflammatory bowel disease. Individuals expressing HLA B27 are at increased risk for the seronegative spondyloarthropathies. __________ References: The genetics of ankylosing spondylitis and axial spondyloarthritis. (http://www.ncbi.nlm.nih.gov/pubmed/23083754)

A 28-Year-Old Man Comes to the Office with a 2-Month