A 56-year-old man is brought to the emergency department due to burning substernal pain that began 6 hours ago. The patient has a history of type 2 diabetes mellitus and hypertension. He smokes 2 packs of cigarettes daily and consumes alcohol occasionally. An ECG performed in the emergency department shows ST segment elevation in leads I, aVL, and V3-V6. During the next several hours, the patient develops progressive shortness of breath that worsens when lying flat. Which of the following histologic features is most likely to be present in this patient's lung tissue?

Question

A 56-year-old man is brought to the emergency department due to burning substernal pain that began 6 hours ago.  The patient has a history of type 2 diabetes mellitus and hypertension.  He smokes 2 packs of cigarettes daily and consumes alcohol occasionally.  An ECG performed in the emergency department shows ST segment elevation in leads I, aVL, and V3-V6.  During the next several hours, the patient develops progressive shortness of breath that worsens when lying flat.  Which of the following histologic features is most likely to be present in this patient's lung tissue?

Quizplus · Accepted Answer

11ec160b_3a02_6725_9249_959427de0d73_MD0001_00 This patient has chest pain and ECG evidence of acute myocardial infarction (MI) involving the lateral wall of the left ventricle. His subsequent development of dyspnea and orthopnea is most likely due to MI-induced acute left ventricular failure, which can result in rapid onset of pulmonary venous hypertension and acute pulmonary edema. Cardiogenic pulmonary edema represents increased filtration of fluid and electrolytes into the lung interstitium and alveoli. The fluid that accumulates is a transudate (an ultrafiltrate of plasma caused by changes in hydrostatic or oncotic pressure) rather than an exudate (an extravasation of not only fluid and electrolytes but also plasma proteins and circulating leukocytes due to inflammatory disruption of the vascular membrane). On light microscopy, engorged alveolar capillaries are evident and the intraalveolar transudate appears as acellular pink material. (Choice A) Fat globules and bone marrow cells in the pulmonary arterioles occur with fat embolism syndrome, which is not a complication of MI but is typically associated with long bone (eg, femur) or pelvic fracture. (Choice B) Focal necrosis of alveolar walls with intraalveolar hemorrhage is typical of pulmonary hemorrhage syndromes such as Goodpasture syndrome and other vasculitides (eg, hypersensitivity angiitis, granulomatosis with polyangiitis). (Choice C) The presence of numerous neutrophils in the alveolar fluid is consistent with exudative alveolar filling, as occurs in bacterial pneumonia. (Choice D) Hemosiderin-laden macrophages ("heart failure cells") form as macrophages digest red blood cells that leak from alveolar capillaries damaged by high intravascular pressure. They are a sign of chronic lung congestion and would not be present acutely. (Choice F) Mononuclear interstitial pulmonary infiltrates are found in various interstitial lung diseases (eg, idiopathic pulmonary fibrosis). Educational objective: Acute pulmonary edema is a common consequence of acute myocardial infarction affecting the left ventricle. Elevated hydrostatic pressure in the pulmonary venous system leads to engorged alveolar capillaries with transudation of fluid into the alveoli, appearing as acellular pink material on microscopy. Hemosiderin-laden macrophages are indicative of chronic lung congestion and are not present acutely.

A 56-Year-Old Man Is Brought to the Emergency Department Due