A 23-year-old woman comes to the office due to progressive low back pain and stiffness. The pain has been present for the last few years and has worsened somewhat in recent weeks. The patient has relief of the pain with physical activity and over-the-counter ibuprofen. Associated symptoms include morning stiffness that usually lasts an hour, but she has had no rash, ocular symptoms, urinary symptoms, or diarrhea. Medical history is notable only for an appendectomy at age 11. The patient has taken birth control pills for the past 2 years and is sexually active with one partner. On examination, she is afebrile with normal height and weight. There is reduced forward flexion of the lumbar spine and tenderness over the lumbosacral area. The remainder of the physical examination is normal. Which of the following would be most likely to establish a diagnosis in this patient?

Question

A 23-year-old woman comes to the office due to progressive low back pain and stiffness.  The pain has been present for the last few years and has worsened somewhat in recent weeks.  The patient has relief of the pain with physical activity and over-the-counter ibuprofen.  Associated symptoms include morning stiffness that usually lasts an hour, but she has had no rash, ocular symptoms, urinary symptoms, or diarrhea.  Medical history is notable only for an appendectomy at age 11.  The patient has taken birth control pills for the past 2 years and is sexually active with one partner.  On examination, she is afebrile with normal height and weight.  There is reduced forward flexion of the lumbar spine and tenderness over the lumbosacral area.  The remainder of the physical examination is normal.  Which of the following would be most likely to establish a diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d504_52c6_bc81_43f82542355b_MD0003_00 This patient has typical features of ankylosing spondylitis (AS), including chronic, progressive back pain and stiffness; pain relief with activity; lumbosacral tenderness; and reduced spinal range of motion. The incidence peaks in individuals age 20-30. Although AS has a male:female ratio of 2:1, it should be considered in any young patient with progressive low back pain and stiffness lasting >3 months. In young patients with characteristic inflammatory back pain, plain x-rays of the pelvis showing sacroiliitis can confirm the diagnosis of AS. However, x-rays may be negative in early stages; MRI can confirm sacroiliitis in such cases. Fusion of the vertebral bodies with ossification of intervertebral discs (bamboo spine) also suggests the diagnosis. There is a strong association between HLA-B27 and AS. However, whereas >90% of patients with AS have HLA-B27, only 5% of patients with HLA-B27 have AS; therefore, HLA-B27 is not specific for AS and testing for it is not necessary for diagnosis. On the other hand, demonstrating radiographic changes of the axial skeleton is necessary for diagnosis (Choice C). (bamboo spine) (Choices A and F) Antinuclear antibodies are characteristically elevated in systemic lupus erythematosus, and rheumatoid factor is usually elevated in rheumatoid arthritis (RA). Both can be abnormal in a variety of other autoimmune disorders, but neither is associated with AS. RA also does not usually involve the spine, except for the cervical region. (Choice B) Acute phase markers (eg, erythrocyte sedimentation rate, C-reactive protein) are usually elevated in AS. However, these tests have very low specificity for establishing the diagnosis. (Choice D) Bone scan is not recommended for diagnosing AS. It is best for identifying osteomyelitis, suspected fractures, and neoplasms. (Choice E) Polymyalgia rheumatica (PMR) is characterized by achy pain in the shoulders and hips associated with elevated acute phase markers. A trial of glucocorticoids can help establish the diagnosis as patients with PMR will have prompt relief of symptoms. However, PMR is not seen before age 50 and does not affect spinal range of motion. Educational objective: Ankylosing spondylitis (AS) is characterized by chronic inflammatory back pain and stiffness, lumbosacral tenderness, and reduced spinal range of motion. In young patients with characteristic pain, plain x-rays showing sacroiliitis can confirm the diagnosis. AS is strongly associated with HLA-B27, but HLA-B27 is not specific for AS and not necessary for diagnosis.

A 23-Year-Old Woman Comes to the Office Due to Progressive