This is a mechanism module, not a specific disease. It is a pathological structure-formation ("Xogenesis") module. Xogenesis anchor: the terminal output is a granuloma (MPATH:847), an OGMS:0000078 pathological anatomical structure produced by an OGMS:0000081 pathological derivation (a new formation assembled from recruited and transformed cells); process genus OGMS:0000061 pathological bodily process. SNOMED "Morphologically abnormal structure" (49755003) is used only as an external census/gap guide and is not bound here. Disorder entries reference individual nodes via conforms_to (for example, "granuloma_formation#Epithelioid Transformation and Multinucleated Giant Cell Formation"). The module defines the expected pathophysiology structure; conforming nodes in disorder files should include the corresponding cell types, biological processes, and causal edges, specialized to their disease context. Key disease-specific substitutions: tuberculosis substitutes M. tuberculosis as the persistent stimulus with caseating necrosis and cavitation at the effector node; sarcoidosis substitutes an unknown antigen with non-caseating granulomas; foreign-body granulomas substitute inert particulate material and typically lack the Th1 adaptive arm. Modules bind GO and CL terms only and do not use chemical (CHEBI) or disease (MONDO) term bindings, except in the treatments block where the therapeutic agent carries an ontology identifier per the treatment schema.
Persistent Indigestible Stimulus
trigger
The proximal trigger of the granulomatous response is a persistent particulate stimulus - an infectious organism, microbial component, or inert foreign material - that resists elimination by an individual macrophage. Because the stimulus cannot be cleared by ordinary phagocytosis, it provokes a sustained, chronic macrophage response rather than resolving acute inflammation. The specific stimulus differs by disorder but the shared feature is its indigestibility and persistence.
Downstream
-
Th1 and TNF-Driven Macrophage Recruitment and Activation
Th1 and TNF-Driven Macrophage Recruitment and Activation
amplifier
Failure to clear the stimulus drives sustained recruitment of monocytes and Th1 (and Th17) lymphocytes that, through interferon-gamma and tumor necrosis factor (TNF), classically activate macrophages at the site. TNF is a non-redundant amplifier: it is required to initiate and organize the granulomatous response, which is why its pharmacological neutralization dissolves granulomas and reactivates latent tuberculosis. This activated, cytokine-rich milieu is the amplifying step that licenses the downstream macrophage transformations.
Downstream
-
Epithelioid Transformation and Multinucleated Giant Cell Formation
Organized Granuloma Assembly
effector
The transformed macrophages assemble into a compact, organized aggregate - an epithelioid/giant-cell core cuffed by lymphocytes and, in some diseases, surrounded by fibroblasts. In diseases such as tuberculosis the center of the granuloma undergoes caseating necrosis and can cavitate; in sarcoidosis the granuloma is characteristically non-caseating. This organized structure is the mature granuloma, the pathological anatomical entity that the module produces.
Downstream
-
Tissue Containment versus Destruction and Fibrosis
Tissue Containment versus Destruction and Fibrosis
consequence
The clinical end state of the module is double-edged. On the protective side, the granuloma sequesters and contains the offending stimulus, limiting its spread. On the pathological side, when the stimulus persists the granuloma drives chronic host tissue destruction, necrosis, cavitation, and fibrotic scarring, which underlies the organ damage of tuberculosis, sarcoidosis, and other granulomatous diseases. Whether containment or destruction dominates is the consequence of the conserved granuloma-formation chain.