A lung biopsy showing ferruginous bodies is indicative of which condition?

The presence of ferruginous bodies in a lung biopsy is strongly associated with asbestosis, a type of pneumoconiosis caused by asbestos exposure. Ferruginous bodies are formed when asbestos fibers become coated with iron-rich protein, reflecting the body's attempt to wall off and isolate the fibers. This is a hallmark of asbestos-related lung diseases and indicates chronic inflammation and fibrosis caused by long-term exposure to asbestos.

In asbestosis, these ferruginous bodies often can be observed under a microscope, providing a clear diagnostic indicator of this specific condition. The development of asbestosis is characterized by the gradual scarring of lung tissue, leading to restrictive lung disease over time.

While other conditions like coal worker's pneumoconiosis and silicosis have their own distinct histological features, they do not present with ferruginous bodies. Viral pneumonia is primarily characterized by different pathological processes, such as inflammation and necrosis without the formation of ferruginous bodies. Thus, the identification of these structures specifically points to asbestosis as the correct answer.