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Difficulty: Very hardRheumatology and Immunology

Evaluate the following complex clinical presentations of patients with underlying autoimmune or rheumatic conditions. Pair each patient's specific complication with the most accurate diagnostic term.

  • A 32-year-old woman with systemic lupus erythematosus develops acute right-sided hemiparesis. Echocardiography demonstrates small, sterile, warty vegetations on both the atrial and ventricular surfaces of the mitral valve.Libman-Sacks endocarditis
  • A 54-year-old man with chronic hepatitis C virus infection presents with palpable purpura on the lower extremities, arthralgias, and a stocking-glove sensory neuropathy. Laboratories reveal normal C3, markedly decreased C4, and positive rheumatoid factor.Mixed cryoglobulinemia syndrome
  • A 48-year-old woman with diffuse cutaneous systemic sclerosis presents with a blood pressure of 220/125 mm Hg, acute oliguric kidney injury, and microangiopathic hemolytic anemia with numerous schistocytes.Scleroderma renal crisis
  • A 42-year-old woman with severe xerophthalmia and xerostomia presents with acute flaccid paralysis. Laboratories show a serum potassium of 2.1 mEq/L, a normal anion gap metabolic acidosis, and a urine pH of 6.8.Type 1 (distal) renal tubular acidosis

Answer

The correct pairings are: the SLE patient with mitral vegetations has Libman-Sacks endocarditis; the hepatitis C patient with purpura and low C4 has mixed cryoglobulinemia syndrome; the systemic sclerosis patient with malignant hypertension has scleroderma renal crisis; and the Sjögren syndrome patient with hypokalemic paralysis has Type 1 (distal) renal tubular acidosis.
Each clinical vignette provides pathognomonic clues for severe complications of rheumatologic diseases: bilateral sterile vegetations in a patient with systemic lupus erythematosus indicate Libman-Sacks endocarditis; hepatitis C with uniquely low C4 and purpura indicates mixed cryoglobulinemia syndrome; malignant hypertension with schistocytes in systemic sclerosis points to scleroderma renal crisis; and hypokalemic non-anion gap metabolic acidosis in Sjögren syndrome reflects Type 1 (distal) renal tubular acidosis.

Step-by-Step Solution

1
Analyze the first presentation involving SLE, acute hemiparesis, and bilateral mitral vegetations.
Identify Libman-Sacks endocarditis.
SLE can cause nonbacterial thrombotic endocarditis with verrucous vegetations on both sides of the valve leaflets, predisposing to systemic thromboembolism such as an ischemic stroke.
2
Evaluate the second presentation with chronic hepatitis C, palpable purpura, neuropathy, and specific complement changes.
Identify mixed cryoglobulinemia syndrome.
This is a classic triad caused by cold-precipitable immune complexes. Rheumatoid factor acts as an IgM directed against IgG, activating the classical complement pathway and resulting in characteristically low C4 with normal C3.
3
Assess the third presentation of diffuse systemic sclerosis with sudden malignant hypertension, kidney injury, and hemolysis.
Identify scleroderma renal crisis.
This life-threatening complication is characterized by vascular remodeling and extreme renin-angiotensin-aldosterone system activation, requiring immediate treatment with ACE inhibitors.
4
Analyze the fourth presentation of dry eyes/mouth with hypokalemic paralysis and normal anion gap metabolic acidosis.
Identify Type 1 (distal) renal tubular acidosis.
Sjögren syndrome frequently involves lymphocytic infiltration of the renal tubules, impairing distal hydrogen ion secretion. This causes severe hypokalemia, which can precipitate life-threatening flaccid paralysis.

Key Concept

Advanced systemic complications of rheumatologic and autoimmune disorders
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Topics

Rheumatology and Immunology

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