A 72-year-old man is brought to the emergency department by his daughter due to worsening … — USMLE Step 2 CK

A 72-year-old man is brought to the emergency department by his daughter due to worsening confusion, dizziness, and recurrent spontaneous epistaxis over the past 48 hours. He also reports that his vision has become increasingly blurred. His medical history is notable for hypertension and mild chronic obstructive pulmonary disease. On physical examination, temperature is $37.2^\circ \text{C}$ ( $99.0^\circ \text{F}$ ), blood pressure is 145/88 mmHg, pulse is 92/min, and respirations are 16/min. Funduscopic examination reveals bilateral retinal hemorrhages and prominently dilated, tortuous retinal veins. Cardiopulmonary examination is unremarkable. Abdominal examination demonstrates a palpable spleen tip 4 cm below the left costal margin.

Laboratory evaluation shows:

Test	Result
Hemoglobin	8.2 g/dL
Mean corpuscular volume	89 fL
Platelets	140,000 /\mu\text{L}
Leukocytes	6,500 /\mu\text{L}
Blood urea nitrogen	18 mg/dL
Creatinine	1.1 mg/dL
Calcium	9.2 mg/dL
Total protein	11.2 g/dL
Albumin	3.4 g/dL

Serum protein electrophoresis demonstrates a large monoclonal spike in the gamma region. Subsequent immunofixation confirms the presence of an IgM monoclonal protein.

Which of the following is the most appropriate next step in the management of this patient's acute symptoms?

A
Administration of intravenous pamidronate
B
Intravenous administration of furosemide
C
Initiation of empiric vancomycin and cefepime
Urgent therapeutic plasma exchangeAnswer
E
Consultation for urgent hemodialysis

Answer

Urgent therapeutic plasma exchange

The patient's presentation of confusion, dizziness, blurred vision, and mucosal bleeding (epistaxis) in the setting of an IgM monoclonal spike and a large gamma gap (Total protein - Albumin > 4 g/dL) is highly characteristic of Waldenström macroglobulinemia (WM) complicated by hyperviscosity syndrome. The pentameric structure of IgM makes it a very large molecule; high serum concentrations drastically increase blood viscosity, leading to sluggish microcirculation. This causes classic funduscopic findings such as dilated, tortuous retinal veins ('sausage-link' appearance) and retinal hemorrhages, as well as neurological symptoms and impaired platelet function. The most appropriate next step in management for acute, symptomatic hyperviscosity is urgent therapeutic plasma exchange (plasmapheresis). This intervention rapidly removes the heavy IgM molecules from the intravascular space, promptly relieving symptoms. Once the acute emergency is managed, definitive therapy targeting the underlying clonal B-cell population can be initiated.

Step-by-Step Solution

Analyze the clinical presentation

The patient has confusion, dizziness, blurred vision, epistaxis, and dilated/tortuous retinal veins.

These are classic neurologic, visual, and bleeding manifestations of hyperviscosity syndrome.

Evaluate the laboratory findings

There is a large gamma gap (Total protein 11.2 - Albumin 3.4 = 7.8 g/dL) and a confirmed IgM monoclonal spike.

This confirms a diagnosis of Waldenström macroglobulinemia, which classically produces large pentameric IgM molecules that significantly increase serum viscosity.

Determine the appropriate acute management

The patient is highly symptomatic from hyperviscosity, requiring immediate intervention.

Therapeutic plasma exchange physically removes the large IgM molecules from the intravascular space, rapidly reversing the potentially fatal neurologic and bleeding complications.

Key Concept

Symptomatic hyperviscosity syndrome in Waldenström macroglobulinemia is a medical emergency that requires urgent therapeutic plasma exchange to mechanically clear IgM molecules.

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