MKSAP Quiz: 3-week history of pain and swelling of right knee
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EDITOR’S NOTE: ACP InternistWeekly now features questions from MKSAP 15. See the Answer and Critique for this question for important information about MKSAP 15.
A 28-year-old woman is evaluated for a 3-week history of pain and swelling of the right knee and ankle. For the past 6 weeks, she has had diffuse, crampy abdominal pain. For the past week, the pain has been accompanied by four to six daily episodes of bloody diarrhea and fecal urgency. She has lost approximately 1.5 kg (3.3 lb) since the onset of her symptoms. She has not noticed a rash or other joint or soft-tissue involvement. She has not traveled outside of her hometown and has a monogamous sexual relationship with her husband. She has no other medical problems and does not take any medications.
On physical examination, temperature is 37.7° C (99.9° F), blood pressure is 128/72 mm Hg, pulse rate is 98/min, and respiration rate is 18/min. The abdomen is soft and diffusely tender to palpation. Bowel sounds are normal, and there is no organomegaly. Rectal examination reveals tenderness of the rectal canal and stool associated with bright red blood. The right ankle and knee are swollen and slightly warm to the touch, and range of motion of these joints elicits pain. The remainder of the physical examination is normal.
Plain radiographs of the ankle and knee are normal. Arthrocentesis is performed. Synovial fluid analysis reveals a leukocyte count of 14,000/µL (92% polymorphonuclear cells, 8% macrophages).
Which of the following is the most likely cause of this patient's joint symptoms?
A. Crystal-induced arthritis
B. Enteropathic arthritis
C. Gonococcal arthritis
D. Whipple disease
MKSAP Answer and Critique
The correct answer is B) Enteropathic arthritis. This item is available online to MKSAP 15 subscribers in the Rheumatology section, Item 23.
This patient's joint symptoms are most likely caused by enteropathic arthritis. She has a 6-week history of crampy abdominal pain and the recent onset of bloody diarrhea and rectal urgency. She also has had weight loss. This clinical presentation raises suspicion for inflammatory bowel disease.
For the past 3 weeks, this patient also has had acute arthritis of the right knee and ankle accompanied by inflammatory features such as tenderness and swelling; her synovial fluid findings confirm the presence of an inflammatory process. The presence of acute oligoarticular arthritis involving the lower extremities in a patient with an inflammatory diarrheal illness is suggestive of enteropathic arthritis; enteropathic arthritis also may manifest as axial arthritis, such as a spondyloarthropathy.
Crystal-induced arthritis typically manifests as acute monoarticular arthritis and would be unlikely in a premenopausal woman.
Gonococcal arthritis may be associated with oligoarticular arthritis, and joint manifestations in this condition may be migratory. However, patients with gonococcal arthritis commonly have tenosynovitis and cutaneous involvement, which are not present in this patient. Furthermore, neither gonococcal nor crystal-induced arthritis would explain this patient's diarrhea and abdominal pain.
Whipple disease is an extremely rare infectious syndrome caused by Tropheryma whippelii. The most common presenting symptom in affected patients is arthritis; other symptoms include diarrhea, malabsorption, and central nervous system and constitutional symptoms. Joint involvement is usually migratory and follows a chronic course.
Key Point
- The presence of acute oligoarticular arthritis involving the lower extremities in a patient with inflammatory bowel disease is suggestive of enteropathic arthritis.