NTR: Lymph node biopsy: necrotizing granuloma (Lab: pathology: biopsies & morphology)

[pnrobinson]

New term request Lymph node biopsy: necrotizing granuloma (samant_101230221928): Granulomatosis

[pnrobinson]

@MickeySegal -- please provide disease context. Dr Astle and I have been working on a new branch for lymph node biopsy. -John Astle: Since there are likely to be multiple necrtotic granulomas per lymph node, is this a synonym of necrotizing lymphadenitis

Here is a description: https://diagnosticpathology.biomedcentral.com/articles/10.1186/s13000-024-01441-0 The histological features are patchy and irregular necrotic areas with the expansion of the paracortical area of lymph nodes. Apoptotic bodies, crescent tissue cells, and proliferating plasmacytoid monocytes are seen in the necrotic area, accompanied by abundant nuclear fragments but a lack of neutrophils and eosinophils. According to the different stages of the disease, it is divided into three types: the proliferative type, the necrotizing type and the xanthomatous type.

Here is another https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8979771/ SNL: most structures in the lymph nodes were destroyed; extensive coagulative necrosis in the cortical and paracortical areas of the lymph nodes was accompanied by a reactive proliferation of histiocytes; there were a large number of nuclear fragments as well as karyopyknosis and karyolysis cells in the necrotic foci; histiocyte infiltration was observed, but neutrophil infiltration was not, and the IHC CD68 was positive

I am unsure if there needs to be a small hierarchy of terms for this?

[MickeySegal]

We have this finding for Cat Scratch Disease and Eosinophilic Granulomatosis with Polyangiitis (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4217511/)

[johnastle]

Hi Peter and nice to "meet" you Dr. Segal. I looked into SimulConsult quite a few years ago and was very impressed/inspired (it's possible I even spoke to you once on the phone). Anyway, I'm still new to this (contributing to the HPO) so trying to get a hang of things, but necrotizing granuloma is a histologic term describing a granuloma associated with necrosis - usually a region of necrosis surrounded by collections of histiocytes. Unfortunately, there is not a uniformly accepted definition of granuloma (one of my mentors once told me she was taught by Juan Rosai, a world-renowned pathologist, that the smallest granuloma is two kissing histiocytes). Usually, however, non-necrotizing granulomas are aggregates of histiocytes, often with epithelioid and/or spindled morphology, sometimes with admixed multinucleated giant cells and/or other inflammatory cells. Necrotizing granulomas are granulomas associated with necrosis, usually granulomas with central necrosis. The prototypical disease with necrotizing granulomas is tuberculosis, but they can be seen in various conditions (often infectious) including those mentioned by Dr. Segal. I think the NCBI StatPearls definition for granuloma is reasonable: https://www.ncbi.nlm.nih.gov/books/NBK554586/#:~:text=A%20granuloma%20is%20a%20focal,with%20other%20inflammatory%20cell%20types. "A granuloma is a focal aggregate of immune cells that forms in response to a persistent inflammatory stimulus. It characteristically demonstrates the compact organization of mature macrophages, which may or may not be associated with other inflammatory cell types." then add that necrotizing granuloma is a granuloma associated with necrosis, often a large granuloma with central necrosis.

John

[johnastle]

p.s. in answer to the question of whether this is a synonym of necrotizing lymphadenitis I would say no. The terms get a little complicated because there is so much overlap, but you can have a lymph node with necrosis (either as part of a reaction such as to infection or autoimmunity/autoinflammatory condition typically with associated inflammation, which would fall under necrotizing lymphadenitis, OR necrosis due to insufficient oxygen without significant inflammation, which I would not consider a "lymphadenitis"). Necrotizing granulomatous lymphadenitis to me is essentially necrotizing lymphadenitis but with associated granulomas. Histiocytic necrotizing lymphadenitis highlights how confusing these terms can be because this term sounds very similar to necrotizing granulomatous lymphadenitis, but most pathologists would not consider the numerous (often aggregated) histiocytes in this condition to be forming granulomas (because they don't look enough like the well-formed tight aggregates of typical granulomas), and this term is actually synonymous with Kikuchi-Fujimoto disease.

[MickeySegal]

We also have this for TB, mycobacterium avium and Eosinophilic granulomatous with polyangiitis (Churg-Strauss).