A 75-year-old man is found unresponsive in his home. Emergency medical services are called by the neighbor, but the patient is pronounced dead at the scene. The patient had a history of hypertension, type 2 diabetes mellitus, and coronary artery disease, as well as a 25-pack-year smoking history. He worked at a coal mine in the remote past and retired as an auto mechanic 15 years ago. Autopsy is performed; a section of lung tissue stained with hematoxylin and eosin is shown below. Which of the following is the most likely cause of this patient's abnormal histopathology findings?

Question

A 75-year-old man is found unresponsive in his home.  Emergency medical services are called by the neighbor, but the patient is pronounced dead at the scene.  The patient had a history of hypertension, type 2 diabetes mellitus, and coronary artery disease, as well as a 25-pack-year smoking history.  He worked at a coal mine in the remote past and retired as an auto mechanic 15 years ago.  Autopsy is performed; a section of lung tissue stained with hematoxylin and eosin is shown below.  Which of the following is the most likely cause of this patient's abnormal histopathology findings?

Quizplus · Accepted Answer

This patient's autopsy demonstrates an abundance of alveolar macrophages filled with brown pigment in the lung parenchyma. Hemosiderin-laden macrophages located in the lungs are usually the result of chronic passive lung congestion in the setting of heart failure (eg, left ventricular systolic dysfunction). Elevated pulmonary venous pressure leads to transudation of fluid across the alveolar-capillary membrane (pulmonary edema) and can cause breaks in the endothelium with extravasation of red blood cells into the alveoli and lung parenchyma. As alveolar macrophages engulf and degrade the extravasated red blood cells, the released iron accumulates as intracellular hemosiderin. Severe left ventricular systolic dysfunction is associated with an increased risk of fatal ventricular arrhythmia (ie, ventricular tachycardia or fibrillation), which was the likely cause of death in this patient. (Choices A and C) Silicosis results from chronic inflammation triggered by inhaled particles of crystalline silica. Histopathology typically shows silicotic nodules consisting of whorls of concentric collagen fibers. As with other causes of interstitial lung disease, excessive deposition of extracellular collagen eventually leads to pulmonary fibrosis. (Choice D) Hyperreactivity of airways to environmental allergens occurs in asthma. Microscopic analysis of sputum may reveal Curschmann spirals, which represent spiral-shaped mucus plugs. (Choice E) Malignant transformation of bronchial epithelial cells underlies the development of most types of lung cancer. Histopathology typically shows hyperchromatic nuclei and poorly organized cell structure, such as in squamous cell carcinoma of the lung. (Choice F) Neutrophil elastase-mediated alveolar septal destruction underlies the pathogenesis of emphysema, which can occur with smoking or alpha-1 antitrypsin deficiency. Microscopy shows cystic enlargement of the airspaces with loss of the normal lobular architecture. Educational objective: Left-sided heart failure leads to chronically elevated pulmonary venous and capillary pressures, with resulting pulmonary edema and extravasation of red blood cells into the alveolar parenchyma. The iron from red blood cells is taken up by alveolar macrophages and stored as hemosiderin, appearing as brown pigment on microscopy.

A 75-Year-Old Man Is Found Unresponsive in His Home