Necrotizing granulomatous inflammation



Necrotizing granulomatous inflammation describes a specific pattern of long-standing or chronic inflammation that often develops as the body responds to certain conditions, infections, or treatments.

Necrotizing granulomatous inflammation

What is a granuloma?

granuloma is a small, rounded collection of immune cells that forms when the body tries to isolate and eliminate a harmful substance, such as an infection or foreign substance.

The immune cells in a granuloma include:

  • Lymphocytes: These are a type of white blood cell that helps coordinate the immune response.
  • Histiocytes: A type of immune cell that engulfs harmful substances. These cells in a granuloma are called “epithelioid histiocytes” because they stick together in a way that looks similar to epithelial cells that line surfaces in your body.
  • Multi-nucleated giant cells: These are large cells that form when several histiocytes fuse together.

What does necrotizing mean?

The word necrotizing refers to dead cells, often seen at the center of a granuloma. This dead tissue results from the immune response and the body’s effort to fight off an infection or harmful substance. When there are no dead cells in the granuloma, it is called a non-necrotizing granuloma.

Why is necrotizing granulomatous inflammation important?

Necrotizing granulomas are significant because they are often associated with specific infections or conditions. Some common causes include:

Infections

  • Tuberculosis: An infection caused by bacteria called Mycobacterium tuberculosis.
  • Fungal infections: A wide variety of fungal species can cause fungal infections. Histoplasma and Aspergillus species are common types associated with necrotizing granulomatous inflammation.

Medical treatments

  • BCG therapy for bladder cancer: This treatment stimulates the immune system using a weakened form of Mycobacterium bovis. While effective in treating certain bladder cancers, it can occasionally cause granulomatous inflammation as a side effect.

Autoimmune diseases

  • Vasculitis, a group of conditions where the immune system attacks blood vessels, leading to inflammation that can include necrotizing granulomas.

How do pathologists investigate necrotizing granulomas?

Because necrotizing granulomas can indicate an infection or another underlying condition, your pathologist may use special stains to identify potential causes. These include:

  • Acid-fast stains are used to detect bacteria like Mycobacterium tuberculosis.
  • Silver stains are used to highlight fungal organisms.

Additional tests, such as molecular studies or cultures, may also be performed to confirm the presence of infectious agents or guide further treatment.

What happens next?

If necrotizing granulomatous inflammation is found, your doctor will use this information along with your medical history, physical exam, and other test results to determine the underlying cause. Further tests may be ordered to confirm the diagnosis if an infection or treatment-related reaction is suspected.

In some cases, necrotizing granulomas are not caused by an infection or treatment but are part of an autoimmune or inflammatory condition. Your healthcare team will work with you to identify the cause and create a treatment plan tailored to your needs.

Understanding this term helps you and your healthcare team take the next steps to address the condition causing the inflammation.

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