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Question 21#

A 28-year-old woman presents to her primary care physician with a 3-month history of fatigue. Her past medical history includes severe acne. She has had 3 uncomplicated vaginal deliveries and has healthy children aged 5, 3, and 2 years. Questioning reveals that she develops an erythematous rash upon minimal sun exposure, and has heavy menstrual periods despite being on oral contraceptives for the past 2 years. For the past 6 months, she has taken minocycline for acne. Physical examination reveals small joint effusions and tenderness to palpation of the knees bilaterally. Lab testing reveals a normocytic anemia, thrombocytopenia, mild hyper-bilirubinemia, and a marked elevation in her ANA titer. Which of the following statements best characterizes this patient’s illness?

A. Her anemia is due to bone marrow suppression from chronic disease
B. Her anemia is due to iron deficiency
C. Minocycline should be discontinued
D. Anti-histone antibodies are likely to be negative
E. The likelihood of this patient developing venous thromboembolism is comparable to the general population

Correct Answer is C

Comment:

This patient likely has drug-induced lupus erythematosus. Minocycline is one of many medications implicated. Other common offenders include procainamide, hydralazine, propylthiouracil, carbamazepine, phenytoin, and isoniazid. Stopping the offending agent is essential and will lead to resolution of the disease in weeks to months. Renal and CNS disease are uncommon in drug-induced lupus; usually skin and joint manifestations predominate. In lupus, immune-mediated hemolysis is the usual cause of the anemia. Although depressed erythropoiesis from anemia of chronic disease (answer a) can contribute to the patient’s low hemoglobin, the elevated bilirubin suggests hemolysis. Likewise, despite the heavy periods from her thrombocytopenia, long-standing iron deficiency anemia (answer b) will cause a low MCV (microcytic anemia). Anti-histone antibodies (answer d) are very common in drug-induced lupus. Answer e is incorrect as patients with lupus (drug-induced or otherwise) have a higher rate of clot formation and may suffer from antiphospholipid antibody syndrome. Although not directly related to venous thromboembolism, long-standing inflammation with lupus accelerates the rate of atherosclerosis, predisposing to arterial occlusive disease over time.