Granuloma

What it means

A compact, organized collection of mature mononuclear phagocytes, which may be but is not necessarily accompanied by accessory features such as necrosis.

Granulomas vary considerably in their degree of complexity, physical size and organization. Not surprisingly, their classification has attracted much attention, and a numbers of schemes have been described. The cornerstone of the granulomatous response, however, is the predominant involvement of mononuclear phagocytes. As granulomas develop, tissue-resident, as well as inflammatory mononuclear phagocytes become intimately acquainted, and these cells may develop highly differentiated epithelioid cell characteristics. In many cases, elegant multinucleate populations can be seen, distinct from the syncytia formed after viral infection as evident by their extended life-span. Accumulating lymphocytes, mainly T cells, contribute to the developing microarchitecture of the granuloma, often with characteristic patterns of subset organization relative to the core of mononuclear phagocytes and to each other. B lymphocytes, plasma cells, NK cells and neutrophils may all be present, though a relative paucity of neutrophils delineates these sites of inflammation from those associated with necrosis. At its extreme, the granuloma may serve as the focus for irreversible fibrotic reactions, but, even in less dramatic cases, a substantive degree of local tissue remodeling occurs.

Rare diseases that can present with this10

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category