Difference Between Caseating and Noncaseating Granuloma

The key difference between caseating and noncaseating granulomas is that caseating granuloma has a whitish, cheese like debris at the center whereas noncaseating granuloma has no such center that has undergone necrosis.

Granulomatous inflammation is one aspect of the chronic inflammatory response where our body attempts to prevent the spread of an infectious agent that it cannot eradicate. A granuloma whose center has undergone caseous necrosis is known as a caseating granuloma. A noncaseating granuloma, on the other hand, is a granuloma that doesn’t have central caseating necrosis.

CONTENTS

1. Overview and Key Difference
2. What is a Granuloma
3. What is a Caseating Granuloma
4. What is a Noncaseating Granuloma
5. Similarities Between Caseating and Noncaseating Granuloma
6. Side by Side Comparison – Caseating vs Noncaseating Granuloma in Tabular Form
7. Summary

What is a Granuloma?

Granulomatous inflammation is a form of chronic inflammation that helps the body to contain the spread of an infectious agent. There is extensive activation of T lymphocytes in this condition, which, in turn, leads to the activation of macrophages. Macrophages acquire a large amount of cytoplasm in this process and consequently start resembling epithelial cells. Therefore, enlarged macrophages in a granuloma are known as epitheliod cells. Moreover, the fusion of these cells forms multinucleated giant cells.

Classification of Granulomas

Depending on the pathogenesis, there are two categories of granulomas; that are immune granuloma and foreign body granuloma.

Foreign body granuloma typically forms around suture materials and talc. These materials do not trigger a specific inflammatory process, but they activate the phagocytosis by macrophages. Macrophages and epitheliod cells surround the foreign body that is at the center of the granuloma.

Infectious agents, which are capable of eliciting a T cell-mediated immune response, trigger the pathogenesis of immune granulomas. First, macrophages get activated; they then activate the T cells. The activated T cells then release cytokines such as IL2 and IFN,  which in turn, activate other T cells and macrophages, respectively.

What is a Caseating Granuloma?

When certain infectious organisms are the causatives of the granuloma formation, the central zone of the granuloma undergoes necrosis because of hypoxia and free radical activity. The necrotic materials at the center have a cheesy white appearance. A caseating granuloma is a granuloma with such a center that has undergone caseous necrosis.

Figure 01: Caseating Granuloma in Tuberculosis

Under the microscope, these necrotic tissues appear as white amorphous masses that have completely lost their cellular architecture. Caseating granulomas are a hallmark feature of tuberculosis.

What is Noncaseating Granuloma?

Noncaseating granuloma refers to all granulomas that do not have a center that has undergone caseating necrosis. Given below is a microscopic image of a noncaseating granuloma.

Figure 02: Microscopic Appearance of a Noncaseating Granuloma

Noncaseating granuloma appears in conditions such as sarcoidosis, leprosy, and Crohn’s disease.

Similarities Between Caseating and Noncaseating Granuloma

• Formation of a granuloma happens in both cases as a response to an intrinsic or extrinsic injurious agent.

Difference Between Caseating and Noncaseating Granuloma

Summary – Caseating vs Noncaseating Granuloma

A caseating granuloma is a granuloma with a center that has undergone caseous necrosis. Noncaseating granulomas include all granulomas that do not have a center that has undergone caseating necrosis. Therefore, the main difference between caseating and noncaseating granuloma is that the noncaseating granulomas do not have a necrotic center while caseating granulomas do.

Reference:

1. Kumar, Vinay, Stanley Leonard Robbins, Ramzi S. Cotran, Abul K. Abbas, and Nelson Fausto. Robbins and Cotran pathologic basis of disease. 9th ed. Philadelphia, Pa: Elsevier Saunders, 2010. Print.

Image Courtesy:

1. “Tuberculosis – Sub-pleural primary (Ghon) focus” by Yale Rosen (CC BY-SA 2.0) via Flickr
2. “Noncaseating Granuloma” by Ed Uthman (CC BY 2.0) via Flickr

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