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Author: Robert A. Kalish, M.D.

Case 1

A 75 year old man presented to his doctor with a chief complaint of bilateral anteromedial knee pain and swelling which had been present for the last two years. His symptoms worsened throughout the day and with progressive weight bearing. Occasionally his fingers hurt as well, making it difficult for him to open jars and button his shirt. Morning stiffness lasted a few minutes. He had no constitutional symptoms.

On physical examination he had tenderness but no warmth at the distal interphalangeal joints. He had small, cool knee effusions and the range of motion in each knee was limited. Crepitation was observed during passive range of motion of the knees.

Synovial fluid aspiration of one of the knee effusions revealed a white count of 1250 cells with very few neutrophils. X-rays of the right knee showed asymmetrical joint space narrowing of the both knees.

  1. What is the cause of the patient's arthritis and the differential diagnosis? How would you describe the pattern of this patient's arthritis?
  2. Would you obtain any further laboratory tests?
  3. Explain the x-ray findings and how they relate to the pathogenesis of the disease.
  4. What other studies of the synovial fluid would you perform, if any?

Case 2

A 77 year old woman had a painful, swollen knee which awoke her from sleep. This had never happened before, and she enjoyed excellent health. She had essential hypertension which was being treated with hydrochlorothiazide. She traveled to Nantucket each summer, and walked the beaches without any joint pain or shortness of breath. She did not recall being bitten by a tick, and had never experienced facial palsy or meningitis. As far as she knew, her heart was normal.

The knee felt warm to her, and the pain was excruciating at times. She could barely walk on it, and used a cane which her husband had. The pain subsided after a couple of weeks. A few weeks later, the other knee became similarily affected.

On physical examination, the temperature was 100 degrees Fahrenheit and the blood pressure was 170/90. The general examination was normal. The right knee examination showed a small effusion but examination of the left knee showed a large, warm effusion with painful range of motion. The knee was stable, without any evidence of mechanical derangement.

Laboratory studies showed a uric acid of 9.3 mg/dl, a negative ANA and RF and a normal CBC and creatinine. Plain films of both knees showed linear calcification in the medial compartments of both knees.

  1. What diagnostic considerations come to mind with this patient's pattern of arthritis, and how can you best differentiate the causes?
  2. How do you interpret the radiographic findings?
  3. Which features of this patient's disease support Lyme disease? Describe the methods used to make the diagnosis of Lyme disease.
  4. Synovial fluid analysis showed a white count of 35,000. What other tests would you perform on the synovial fluid?
  5. Describe the features identified by polarizing microscopy.

Case 3

A 22 year old man noted recurrent right wrist swelling in the absence of trauma or fever. This arthritis had taken place several times over the last year. Most recently, the right fourth toe became swollen and tender. A doctor thought the toe swelling might be due to an infection but the pain and swelling continued despite a three week course of antibiotics. Over the counter antinflammatory agents helped a little. He also noticed some buttock and heel pain. He had no diarrhea, and was sexually active. On examination, all of the vital signs were normal and he had a few patches of erythema over the scalp, and in the umbilicus and intergluteal cleft. There was a prominent aphthous ulcer in the left buccal mucosa. He did not have a murmur, and the remainder of the general physical examination was normal. The musculoskeletal examination showed swelling in the right wrist, and a diffusely swollen fourth toe, resembling a sausage. The nails were abnormal, with pits in the centers of the nailbeds. Examination of the Achilles' tendons was unremarkable but the heels were tender.

Laboratory studies showed an ESR of 74 mm/hr, and a negative RF and negative ANA.

X-rays of the right wrist showed early erosions. The x-ray of the sacroiliac joint was also abnormal, showing erosions.

  1. How would you describe the pattern of this patient's arthritis? What rheumatic diseases are characterized by this pattern?
  2. What is the cause of the rash, and describe the relationship of the rash to the patient's arthritis. If the rash were more extensive, would the arthritis be worse? What is the significance of the "pits" seen in the nailbeds?
  3. What genetic factor might be associated with this disease?
  4. You decide to perform a synovial fluid aspiration of the right wrist. Predict the synovial fluid white count. What other studies would you perform with the synovial fluid?
  5. What is an erosion?

Case 4

An 18 year old woman noticed some pain in the lateral aspect of the right ankle one morning upon awakening. This resolved after a couple of weeks, and she did not seek medical attention for it despite some swelling and warmth which was associated with the pain. A month later her left index finger was painful, warm, and swollen, and she had difficulty buttoning her clothes and using her computer. Other joints in her hands became involved symmetrically. This lasted a few weeks, and she decided to see her doctor after her right knee became swollen and painful. She had night sweats, and was losing weight. Sharp pain on breathing deeply developed. Morning stiffness lasted for several hours. Her menses were normal.

When she was examined, the oral temperature was 99 degrees Fahrenheit. She had diffuse lymphadenopathy. There were no oral ulcers. She had nodules over the extensor surfaces of both proximal ulnae, and synovitis was noted in the wrists, and metacarpophalnageal joints. The knees were warm and swollen, as were the ankles and metatarsophalangeal joints. Auscultation of the chest showed diminished breath sounds at the left base, without a rub and the cardiac examination revealed distant heart sounds.

Some laboratory tests had been available at the time of her initial evaluation with you and showed an ESR of 110 mm/hr, and normochromic normocytic anemia.

  1. Describe the pattern of this patient's arthritis, and the differential diagnosis based on the pattern. Does this patient have JRA? Why or why not?
  2. What serological studies would you obtain to help make the diagnosis?
  3. Identify the extrarticular features of this patient's illness and describe possible causes of these features. Do these features make one diagnosis more likely? What is the pathology of the nodule?
  4. Synovial fluid aspiration of the left knee was performed. Predict the synovial fluid white count.