Course Case Studies

Pathophysiology: The Immune System

Course #38430 - $75 • 15 Hours/Credits

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  • Participation Instructions
    • Review the course material online or in print.
    • Complete the course evaluation.
    • Review your Transcript to view and print your Certificate of Completion. Your date of completion will be the date (Pacific Time) the course was electronically submitted for credit, with no exceptions. Partial credit is not available.
Learning Tools - Case Studies


Patient A is a married black woman, 47 years of age, with two children and an 18-year history of systemic lupus erythematosus. She has no known allergies. The patient takes an occasional naproxen for joint pain and antacid for heartburn, but reports no other prescription or over-the-counter medications. She neither smokes nor drinks alcohol. Except for lupus, the patient's medical history is unremarkable.

Patient A is 5 feet 5 inches in height and weighs 102 pounds, a decrease in weight of 23 pounds since her last physical exam nearly one year ago. She has four brothers and three sisters. An older sister has rheumatoid arthritis, an aunt has pernicious anemia, and her deceased mother had hyperthyroidism (Graves disease).

At presentation, the patient's blood pressure is 110/70 mm Hg, heart rate is 70 beats per minute, and oral temperature is 99.9°F. Her respiration is unlabored at 15 breaths per minute.

Eighteen years ago, Patient A complained to her primary care provider of multiple rashes that developed on her arms and legs whenever she went out into the sun. She also complained of several small patches of hair loss on her head that she attributed to stress and anxiety experienced during an airplane trip (as she has a fear of flying). Furthermore, she mentioned at that time she lacked energy, became tired very easily, and always needed to take at least one nap each day. She reported mild arthritic pain in her fingers and elbows, but attributed the joint discomfort to "growing old." Her erythrocyte sedimentation rate was 25 mm/hour.

Patient A had been aware of these problems for approximately four months. A physical examination was conducted, during which the primary care provider noted multiple rash-like lesions on sun-exposed areas of the body, primarily on the arms and legs. A tissue biopsy of one of the lesions was taken and microscopic examination of the tissue revealed vasculitis (white blood cells within the walls of blood vessels). An ANA test was positive. The lungs were clear to auscultation, heart sounds were normal with a prominent S1 and S2, and there was no evidence of enlarged lymph nodes. Blood tests revealed a hematocrit of 23% and a red blood cell count of 3.5 million/mcL. She was also slightly jaundiced, with some yellowing within the sclera. Microscopic examination of a peripheral blood smear revealed that red blood cells were normal in shape, size, and color, ruling out iron, folate, and vitamin B12 deficiencies. The total white blood cell count was 5,500/mcL, and her pitted erythrocyte count was 350,000/mcL. Urinalysis was normal. She was placed on prednisone for two months, during which time all signs and symptoms of disease resolved.

Five years ago, Patient A presented again to her primary care provider, this time complaining of a productive cough and stiffness and pain in her hands and feet that seemed to come and go and to affect different joints (migratory polyarthritis). She was afraid that she was developing rheumatoid arthritis like her older sister.

Her blood pressure at this time was 140/90 mm Hg and heart rate 105 beats per minute, and she had a temperature of 100°F. Auscultation of the lungs revealed abnormal lung sounds, suggesting that she had bronchitis. A chest x-ray revealed mild pulmonary edema but no white blood cell infiltrates in the terminal airways. The primary care provider was concerned about susceptibility for developing pneumonia. Axillary and inguinal lymph nodes were slightly enlarged. Blood tests revealed a hematocrit of 43%, a platelet count of 330,000/mcL, and a total white blood cell count of 1,200/mcL. A urinalysis was essentially normal.

The patient was given a 10-day course of antibiotic therapy to prevent pneumonia and placed on prednisone again. All signs and symptoms resolved within three months.

Today, Patient A returns to her primary care provider complaining of fatigue, anorexia, weight loss, and significant swelling in the abdomen, face, and ankles. The primary care provider notes that a "butterfly-shaped" rash is present across the bridge of her nose and cheeks. Blood tests reveal a hematocrit of 24%. The white blood cell count is 2,400/mcL. A dipstick examination of the urine reveals an abnormal protein concentration, and microscopy shows the presence of significant numbers of red and white blood cells. A 24-hour urine protein collection reveals excretion of 2.5 g protein/24 hours.

  1. What is the relevance of the current information to her disease?

  2. What is the significance of the patient's family history?

  3. Explain the pathophysiology that underlies hair loss in this patient and the relevance of the abnormal erythrocyte sedimentation rate.

  4. What might have caused the lack of energy in this patient, and what type of tests might be ordered to support this conclusion?

  5. Vasculitis in lupus results from the trapping of antigen-antibody complexes in blood vessel walls followed by an intense inflammatory response to the immune complexes. Why is prednisone effective in relieving vasculitis?

  6. What is the most likely cause of jaundice in this patient?

  7. What is the pathophysiology that underlies lymph node enlargement in this patient?

  8. Which of the three blood test results would be of most concern? Give a likely cause for the abnormality.

  9. The patient's white blood cell differential was 75% neutrophils, 15% lymphocytes, 5% monocyte/macrophages, 4% eosinophils, and 1% basophils. Which one of these five white blood cell types has been specifically targeted by the patient's immune system?

  10. Give a reasonable explanation for the cause of tachycardia and elevated blood pressure in this patient.

  11. Patients with systemic lupus erythematosus should receive an influenza vaccination every year and a pneumococcal vaccination every five years. Why?

  12. Why is hypocomplementemia consistent with a diagnosis of systemic lupus erythematosus?

Learning Tools - Case Studies


A white man, 32 years of age, presents to the emergency department with a fever of 102.5°F. He was diagnosed with HIV infection approximately three years previously, when he presented to his primary care provider with oral thrush. He was offered cART and stayed on this regimen until approximately 10 months ago, when he lost his job and insurance and could no longer pay for the drugs and discontinued all treatment. He has felt more "run down" recently. For the past two to three weeks, he has had fever, a nonproductive cough, and shortness of breath with mild exertion, such as when cleaning his house. On examination, his blood pressure is 134/82 mm Hg, pulse 110 beats per minute, and respiratory rate 28 breaths per minute. His oxygen saturation on room air at rest is 89% but drops to 80% when he walks 100 feet, and his breathing becomes quite labored. His lungs are clear to auscultation, but white patches cover his buccal mucosa. Otherwise, his examination is unremarkable. Laboratory testing shows a leukocyte count of 2,800 cells/mcL. Serum lactic (acid) dehydrogenase is 540 IU/L.

  1. What is the most likely diagnosis?

  2. What is your next step?

  3. What other diagnoses should be considered?

Learning Tools - Case Studies


A Hispanic woman, 26 years of age, presents to the emergency department on a Saturday afternoon with complaints of bleeding from her nose and mouth since the previous night. She also noticed small, reddish spots on her lower extremities when she got out of bed in the morning. She denies fever, chills, nausea, vomiting, abdominal pain, or joint pain. The patient reports she had developed an upper respiratory infection two weeks prior to the visit, but the infection has now resolved. She denies significant medical problems. Her menses have been normal, and her last menstrual period was approximately two weeks ago. She denies excessive bleeding in the past. Prior to this episode, she never had epistaxis, easy bruisability, or bleeding into her joints. There is no family history of abnormal bleeding. The patient does not take any medications.

On examination, the patient is alert, oriented, and somewhat anxious. Her blood pressure is 110/70 mm Hg, her heart rate is 90 beats per minute, and she is afebrile. No pallor or jaundice is noted. There is bright red oozing from the nose and the gingiva. Skin examination reveals multiple 1-mm flat, reddish spots on her lower extremities. The rest of the examination is normal. There is no lymphadenopathy or hepatosplenomegaly. Her complete blood count is normal, except for a platelet count of 18,000/mcL. Prothrombin time and partial thromboplastin time are normal.

  1. What is your most likely diagnosis?

  2. What is the best initial treatment?

  • Back to Course Home
  • Participation Instructions
    • Review the course material online or in print.
    • Complete the course evaluation.
    • Review your Transcript to view and print your Certificate of Completion. Your date of completion will be the date (Pacific Time) the course was electronically submitted for credit, with no exceptions. Partial credit is not available.