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* Enlarged endothelial cells
* Enlarged endothelial cells
* Thrombi
* Thrombi
Lupus is a chronic [[Autoimmunity|autoimmune disease]] in which the body's own defense system attacks otherwise healthy tissue.  The body's immune system produces antibodies against itself, particularly against proteins in the cell nucleus.  Because of genetic variations in different components of the immune system, in some people the immune system attacks these nuclear-related proteins and produces antibodies against them.  In the end, these antibody complexes damage blood vessels in critical areas of the body, such as the [[glomeruli]] of the kidney; these antibody attacks are the cause of SLE.
SLE is a chronic [[inflammation|inflammatory]] disease believed to be a [[Hypersensitivity#Type 3 - immune complex|type III hypersensitivity]] response with potential [[Hypersensitivity#Type 2 - antibody-dependent|type II]] involvement.<ref>[http://pathmicro.med.sc.edu/ghaffar/hyper00.htm University of South Carolina School of Medicine lecture notes, Immunology, Hypersensitivity reactions. General discussion of hypersensitivity, not specific to SLE.]</ref>
Clinically, it can affect multiple organ systems including the heart, skin, joints, kidneys and nervous system.  The exact mechanisms for the development of systemic lupus erythematosus (SLE) are still unclear since the pathogenesis is a multifactorial event. 
Minimal mesangial lupus nephritis (class I): mesangial immune deposits that are identified by immunofluorescence alone or by both immunofluorescence and electron microscopy, but such patients do not have light microscopic abnormalities
Mesangial proliferative lupus nephritis (class II): mesangial hypercellularity (of any degree) or mesangial matrix expansion
A few isolated subepithelial or subendothelial deposits may be seen on immunofluorescence or electron microscopy
Focal lupus nephritis (class III): Light microscopy: Active or inactive endocapillary or extracapillary segmental glomerulonephritis (Less than 50 percent of glomeruli are affected)
Electron microscopy: immune deposits in the subendothelial space of the glomerular capillary and mesangium
Glomeruli affected by fibrinoid necrosis and crescents
Presence of tubulointerstitial or vascular abnormalities
Diffuse lupus nephritis (class IV): Light microscopy: more than 50 percent of glomeruli are affected that display endocapillary with or without extracapillary glomerulonephritis and Mesangial abnormalities
Electron microscopy: subendothelial deposits, at least during the active phase and diffuse wire loop deposits, but with little or no glomerular proliferation 
===Genetics===
The first mechanism may arise genetically. Research indicates that [[SLE]] may have a [[genetics|genetic]] link.  Lupus does run in families, but no single "lupus gene" has yet been identified.  Instead, multiple genes appear to influence a person's chance of lupus developing when triggered by environmental factors.  Researchers are now identifying the individual genes, the proteins they produce, and their role in the immune system. Each protein is a link on the autoimmune chain, and researchers are trying to find drugs to break each of those links. <ref name="rahman">{{cite journal |author=Anisur Rahman and David A. Isenberg|title=Review Article: Systemic Lupus Erythematosus|journal=N Engl J Med|volume=358|issue=9|pages=929–939|year=2008|date=February 28, 2008|pmid=18305268|url=http://content.nejm.org/cgi/content/full/358/9/929|doi=10.1056/NEJMra071297}}</ref><ref>{{cite journal |author=Mary K. Crow|title=Collaboration, Genetic Associations, and Lupus Erythematosus|journal=N Engl J Med|volume=358|issue=9|pages=956–961|year=2008|date=February 28, 2008|pmid=18204099|url=http://content.nejm.org/cgi/content/full/358/9/956|doi=10.1056/NEJMe0800096}}</ref><ref>{{cite journal |author=Geoffrey Hom, Robert R. Graham, Barmak Modrek, et al.|title=Association of Systemic Lupus Erythematosus with C8orf13–BLK and ITGAM–ITGAX|journal=N Engl J Med|volume=358|issue=9|pages=900–909|year=2008|date=February 28, 2008|pmid=18204098|url=http://content.nejm.org/cgi/content/full/358/9/900|doi=10.1056/NEJMoa0707865}}</ref>
* The most important [[gene]]s are located on [[Chromosome 6 (human)|chromosome 6]], where mutations may occur randomly (''de novo'') or be inherited.
* Additionally, people with SLE have an altered RUNX-1 binding site, which may be either cause or contributor (or both) to the condition. Altered binding sites for RUNX-1 have also been found in people with [[psoriasis]] and [[rheumatoid arthritis]].
Other abnormalities include:
*Increased expression of [[FcεRI]]γ, which replaces the sometimes deficient TCR ζ chain
*Increased and sustained calcium levels in [[T cell]]s
*Moderate increase of [[inositol triphosphate]]
*Reduction in [[Protein kinase C|PKC]] phosphorylation
*Increased desire of animal protein intake.
*Reduction in Ras-[[Mitogen-activated protein kinase|MAP kinase]] signaling
*Deficiencies in [[protein kinase]] A I activity
===Environmental triggers===
The second mechanism may be due to environmental factors. These factors may not only exacerbate existing lupus conditions, but also trigger the initial onset. They include:
* Certain medications (such as some [[antidepressant]]s and [[antibiotic]]s)
* Extreme [[stress]]
* Exposure to sunlight
* [[Hormones]]
* [[Infection]]s - some researchers have sought to find a connection between certain infectious agents ([[virus]]es and [[bacteria]]), but no pathogen can be consistently linked to the disease.
* [[UV]] radiation has been shown to trigger the photosensitive lupus rash, but some evidence also suggests that UV light is capable of altering the structure of the DNA, leading to the creation of [[autoantibodies]].
* Some researchers have found that women with [[silicone]] gel-filled [[breast implant]]s have produced antibodies to their own [[collagen]], but it is not known how often these antibodies occur in the general population and there is no data that show these antibodies cause [[connective tissue disease]]s such as [[lupus]].
===Abnormalities in apoptosis===
*[[Apoptosis]] is increased in [[monocyte]]s and [[keratinocyte]]s
*[[Gene expression|Expression]] of Fas by [[B cell]]s and [[T cell]]s is increased
*There are correlations between the apoptotic rates of lymphocytes and disease activity
Tangible body macrophages (TBMs) are large phagocytic cells in the [[germinal center]]s of secondary [[lymph node]]s. They express CD68 protein.  These cells normally engulf B cells which have undergone apoptosis after [[somatic hypermutation]].  In some patients with SLE, significantly fewer TBMs can be found, and these cells rarely contain material from apoptotic B cells. Also, uningested apoptotic nuclei can be found outside of TBMs. This material may present a threat to the tolerization of B cells and T cells. [[Dendritic cell]]s in the germinal center may endocytose such antigenic material and present it to T cells, activating them. Also, apoptotic chromatin and nuclei may attach to the surfaces of follicular dendritic cells and make this material available for activating other B cells which may have randomly acquired self-specificity through [[somatic hypermutation]].<ref>{{cite journal | author=Gaipl, U S; Kuhn, A; Sheriff, A; Munoz, L E; Franz, S; Voll, R E; Kalden, J R; Herrmann, M | title=Clearance of apoptotic cells in human SLE.| journal=Current directions in autoimmunity | volume=9 | issue= | year=2006 | pages=173-87 | url = http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16394661&dopt=Abstract | id = PMID: 1639466 [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16394661&dopt=Abstract Abstract] (full text requires registration) }}</ref>
===Clearance deficiency===
[[image:Picture1_englisch.jpg|left|thumb|Clearance deficiency]]Beside discussed causations, impaired clearance of dying cells is a potential pathway for the development of this systemic [[autoimmune disease]]. This includes deficient phagocytic activity, scant serum components in addition to increased [[apoptosis]].
[[Monocytes]] isolated from [[whole blood]] of SLE patients show reduced expression of CD44 surface molecules involved in the uptake of apoptotic cells. Most of the [[monocyte]]s and tingible body macrophages (TBM), which are found in the germinal centres of [[lymph nodes]], even show a definitely different morphology in patients with SLE. They are smaller or scarce and die earlier. Serum components like complement factors, [[CRP]] and some [[glycoproteins]] are furthermore decisively important for an efficiently operating phagocytosis. In patients these components are often missing, diminished or inefficient.
The clearance of early apoptotic cells is an important function in multicellular organisms. It leads to a progression of the apoptosis process and finally to secondary [[necrosis]] of the cells, if this ability is disturbed. Necrotic cells release nuclear fragments as potential autoantigens as well as internal danger signals, inducing [[maturation]] of [[dendritic cells]] (DC), since they have lost their membranes integrity. Increased appearance of apoptotic cells also is simulating inefficient clearance. That leads to maturation of DC and also to the presentation of intracellular antigens of late apoptotic or secondary necrotic cells, via MHC molecules.
[[Autoimmunity]] possibly results by the extended exposure to nuclear and intracellular autoantigens derived from late apoptotic and secondary necrotic cells. B and [[T cell]] tolerance for apoptotic cells is abrogated and the [[lymphocytes]] get activated by these autoantigens; [[inflammation]] and the production of autoantibodies by [[plasma cells]] is initiated. A clearance deficiency in the skin for apoptotic cells has also been observed in patients with cutaneous lupus erythematosus (CLE).
===Accumulation in germinal centres (GC)===
[[image:Picture2_englisch.jpg|left|160px|thumb|Germinal centres]]
In healthy conditions apoptotic lymphocytes are removed in germinal centres by specialised phagocytes, the tingible body macrophages (TBM); that’s why no free apoptotic and potential autoantigenic material can bee seen.
In some patients with SLE accumulation of apoptotic [[debris]] can be observed in GC, because of an ineffective clearance of apoptotic cells.
In close proximity to TBM, [[follicular dendritic cells]] (FDC) are localized in GC, which attach antigen material to their surface and in contrast to bone marrow-derived DC, neither take it up nor present it via MHC molecules.
Autoreactive [[B cells]] can accidentally emerge during [[somatic hypermutation]] and migrate into the GC light zone. Autoreactive B cells, maturated coincidently, normally don’t receive survival signals by antigen planted on follicular dendritic cells and perish by apoptosis.
In the case of clearance deficiency apoptotic nuclear debris accumulates in the light zone of GC and gets attached to FDC. This serves as a germinal centre survival signal for autoreactive B-cells.
After migration into the mantle zone autoreactive B cells require further survival signals from autoreactive helper T cells, which promote the maturation of autoantibody producing plasma cells and B memory cells.
In the presence of autoreactive T cells a chronic [[autoimmune disease]] may be the consequence.
<br clear="left" />
===Drug reactions===
[[Drug-induced lupus erythematosus]] is a reversible condition that usually occurs in patients being treated for a long-term illness. Drug-induced lupus mimics systemic lupus. However, symptoms of drug-induced lupus generally disappear once a patient is taken off the medication which triggered the episode.
===Anti-nRNP autoimmunity===
[[Autoantibodies]] to nRNP A and nRNP C initially targeted restricted, [[proline]]-rich motifs. Antibody binding subsequently spread to other [[epitopes]]. The similarity and [[cross-reactivity]] between the initial targets of nRNP and Sm autoantibodies identifies a likely commonality in cause and a focal point for intermolecular epitope spreading.<ref name="pmid19248110">{{cite journal |author=Poole BD, Schneider RI, Guthridge JM, ''et al'' |title=Early targets of nuclear RNP humoral autoimmunity in human systemic lupus erythematosus |journal=Arthritis Rheum. |volume=60 |issue=3 |pages=848–859 |year=2009 |month=February |pmid=19248110 |doi=10.1002/art.24306 |url=http://dx.doi.org/10.1002/art.24306 |issn=}}</ref>
===Others===
Elevated expression of HMGB1 was found in the sera of patients and mice with systemic lupus erythematosus, High Mobility Group Box 1 (HMGB1) is a [[nuclear]] [[protein]] participating in [[chromatin]] architecture and [[transcription|transcriptional regulation]]. Recently, there is increasing evidence that HMGB1 contributes to the pathogenesis of [[chronic]] [[inflammatory]] and [[autoimmune diseases]] due to its pro-inflammatory and immunostimulatory properties.<ref name="pmid19247800">{{cite journal |author=Pan HF, Wu GC, Li WP, Li XP, Ye DQ |title=High Mobility Group Box 1: a potential therapeutic target for systemic lupus erythematosus |journal=Mol. Biol. Rep. |volume= |issue= |pages= |year=2009 |month=February |pmid=19247800 |doi=10.1007/s11033-009-9485-7 |url= |issn=}}</ref>
===Gross Images===
[http://www.peir.net Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology]
===Microscopic Images===


[http://www.peir.net Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology]
[http://www.peir.net Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology]

Revision as of 18:41, 26 June 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2] Raviteja Guddeti, M.B.B.S. [3]

Overview

The progression of systemic lupus erythematosus involves the immune system. There are other factors like genetic factors, hormonal abnormalities, and environmental factors that play some roles as well. The most prominent events involving immune abnormalities are related to persistent activation of B cells and plasma cells that make auto-antibodies more auto antibodies during disease progression. The most prominent events involving hormonal abnormalities are due to prolactin and estrogen. The most important environmental factors related to disease progression are ultraviolet (UV) light and some infections. On microscopic histopathological analysis, apoptotic keratinocytes, vacuolization of the basement membrane, and dermal mucin deposition are characteristic findings of SLE dermatitis, and active or inactive endocapillary or extracapillary segmental glomerulonephritis are characteristic findings of SLE nephritis.

Pathogenesis

The progression of systemic lupus erythematosus involves the immune system. Near all of the pathologic manifestation of SLE are due to antibody formation and the creation of immune complexes in different organs of the body. When the immune complexes designed, they will deposit in different body tissues and vessels, which will lead to more complement activation and more organ damage. There are other factors like genetic factors, hormonal abnormalities, and environmental factors that play some roles as well.

Immune abnormalities

Development of systemic lupus erythematosus (SLE) is the result of different mechanisms that at the end lead to auto-immune response of the body. As a result, body tissues lose their self-tolerance. Affected patients are no longer entirely tolerant to all of their self-antigens and consequently progress an autoimmune disease and develop auto antibodies as a response. During disease progression, B cells and plasma cells that make auto-antibodies are more persistently activated and thus make more auto antibodies. These auto antibodies are targeted predominantly to intracellular nucleoprotein particles 

8519610 

This increase in auto antibody production and persistence suppose to be down regulated by anti-idiotypic antibodies or regulatory immune cells, but due to immunologic response it is not appropriately been responded. 

The most important immune abnormalities that are related to SLE develop and progression: 

  • Increase in circulating plasma cells and memory B cells that is associated with SLE activity
  • Decrease in cytotoxic T cells and in functions of suppressor T cells and impaired generation of polyclonal T-cell cytolytic activity
  • Increase in helper T cells and also their function
  • Polyclonal activation of B cells and abnormal B-cell receptor signaling
  • Prolonged lives of B cells
  • Signaling abnormalities of T and B lymphocytes
    • Cellular hyperactivity
    • Hyperresponsiveness
    • May be due to genetically defects
  • Increased expression of IFN-alpha-inducible RNA transcripts by mononuclear cells that lead to elevated levels of IFN-alpha.  15593221
  • Increase in specific genetic factors expression that may be associated with autoimmunity promotion
  • Dysfunctional signaling in T and B cells that may be due to:
    • Increased calcium responses to antigen stimulation
    • Hyperphosphorylation of cytosolic protein substrates
    • Decreased nuclear factor kB
    • Abnormal voltage-gated potassium channels: These channels facilitate excessive calcium entry into T cells
  • Increased levels of microparticles (MPs):
    • Microparticles are small, membrane-bound vesicles enclose DNA, RNA, nuclear proteins, cell-adhesion molecules, growth factors, and cytokines.
    • They are shed from cells during apoptosis or activation
    • Microparticles can drive inflammation and autoimmunity by their derivatives 23672591
  • Elevated levels of circulating TNF-alpha correlate with active disease, and TNF is expressed in renal tissue in lupus nephritis
  • abnormally high levels of E-C4d and low levels of E-CR1 are characteristic of SLE, and combined measurement of the 2 molecules has high diagnostic sensitivity and specificity for lupus.
  • Increased numbers of circulating neutrophils undergoing NETosis, a form of apoptosis specific for neutrophils, releases DNA bound to protein in protein nets, which stimulates anti-DNA and IFN-alpha production
  • Increased neutrophil extracellular trap formation: 26658004
    • It may promote thrombus formation
    • It is associated with increased disease activity and renal disease and thus can be used even as a disease activity marker.
    • It can damage and kill endothelial cells and promote inflammation in atherosclerotic plaques, which may contribute to accelerated atherosclerosis in systemic lupus erythematosus
  • These changes promote the production of antinuclear antibodies

Hormonal abnormalities

The following evidence is suggestive of the hormonal predisposition of SLE:

  • Sexual predilection of females: Shows the relationship of female hormones and the onset of SLE
  • Significantly increased risk for SLE in:17393454
    • Early age of menarche
    • Early age at menopause or surgical menopause
    • Women that are treated with estrogen-containing regimens such as oral contraceptives or postmenopausal hormone replacement therapies

Hormones that are related to SLE disease progression:10503654

  • Gonadotrophins like prolactin
    • Stimulants of immune functions and is elevated in SLE
  • Exogenous estrogen - include oral contraceptive use and post-menopausal hormone replacement therapy: 10503654- 25155581
    • Stimulates the type 1 IFN pathway
    • Stimulates thymocytes, CD8+ and CD4+ T cells, B cells, macrophages, the release of certain cytokines (eg, IL-1)
    • Prompt maturation of B cells especially those that have a high affinity to ant-DNA antibodies by decreasing the apoptosis of this self-reactive B-cells 16724801
    • Stimulate expression of HLA and endothelial cell adhesion molecules (VCAM, ICAM)
    • Increases macrophage proto-oncogene expression
    • Enhanced adhesion of peripheral mononuclear cells to endothelium
  • Progesterone:
    • May inhibit the type 1 interferon pathway, suggesting that a balance between estrogen and progesterone may be critical for the body to remain healthy
    • Downregulates T-cell proliferation and increases the number of CD8 cells
  • Both progesterone and high levels of estrogen promote a Th2 response, which favors autoantibody production

Environmental factors

  • Infections can stimulates some antigen specific cells and lead to SLE disease:
    • Epstein-Barr virus (EBV): may induce anti-DNA antibodies or even lupus-like symptoms. It is associated with higher risk of SLE and also triggering the active course of disease in children
    • Trypanosomiasis or mycobacterial infections may have the same effect as EBV
    • SLE active disease flares may follow bacterial infections as well
  • Ultraviolet (UV) light: Can stimulates B-cells to produce more antibodies. It can also interfere with antigen processing by activation of macrophages and hence increase the degree of autoimmunity

Genetics

Systemic lupus erythematosus is transmitted in poly-genic inheritance pattern. Genes involved in the pathogenesis of systemic lupus erythematosus include HLA class polymorphism, complement genes, and other genes related to immunologic system as well.

The following evidence is also suggestive of the genetic predisposition of SLE:

  • Increase of disease occurrence in identical twins
  • The increase in frequency of SLE among first degree relatives
  • The increased risk of developing the disease in siblings of SLE patients
Gene class Gene subtype
HLA genes DR2, DR3, DR4, DR7, DR8, DRw12, DQw2, DQA1,

DQB1, DQ6, DQw6, DQ7, DQw7, DQw8, DQw9, B61, B8

Complement genes C2, C4, C1q
Non-HLA genes Mannose binding lectin polymorphisms

Tumour necrosis factor α

T cell receptor

Interleukin 6

CR1

Immunoglobulin Gm and Km

FcγRIIA (IgG Fc receptor)

FcγRIIIA (IgG Fc receptor)

PARP (poly-ADP ribose polymerase)

Heat shock protein 70

Humhr 3005

10768211

Homozygous deficiencies of the components of complement especially C1q are associated with developing immunologic diseases especially SLE or a lupus-like disease : 11564823 The FcγRIIA polymorphism has been associated with nephritis in African Americans and Koreans as well as Hispanic patients. Both FcgammaRIIa and FcgammaRIIIa have low binding alleles that confer risk for SLE and may act additively in the pathogenesis of disease24997134

Associated Conditions

IC deposition and subsequent complement activation in the kidney is responsible for much of the tissue damage of lupus nephritis

Gross Pathology

On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name]. Gross, enlarged very pale kidneys with flea bite or ectasia.

A good example of kidneys from a patient with nephrotic syndrome (subacute glomerulonephritis) File:Systemic lupus erythematosus 001.jpg File:Systemic lupus erythematosus 046.jpg Lupus Erythematosus Libman Sacks Embolism: Gross fixed tissue large hemorrhagic infarcts due to embolism 19yo female with known lupus and history of TIAs File:Systemic lupus erythematosus 027.jpg Lupus Erythematosus Libman Sacks Endocarditis: Gross natural color mitral valve small lesions but cause much trouble in form of TIAs and terminally multiple hemorrhagic brain infarcts File:Systemic lupus erythematosus 021.jpg Brain: Lupus Erythematosus, Systemic; Microinfarct in Cerebral Cortex File:Systemic lupus erythematosus 047.jpg Lupus Erythematosus Hepatitis: Gross natural color. A 19yo female with lupus erythematosus and hepatitis characterized by periportal cell necrosis and sinus thrombosis cause uncertain photo shows focal grid-like hyperemia File:Systemic lupus erythematosus 004.jpg

Microscopic Pathology

On microscopic histopathological analysis, apoptotic keratinocytes, vacuolization of the basement membrane, and dermal mucin deposition are characteristic findings of SLE dermatitis, and active or inactive endocapillary or extracapillary segmental glomerulonephritis are characteristic findings of SLE nephritis.

Skin histo-pathology:

Common shared histopathologic features among all different subtypes of cutaneous lupus include:

  • Hyperkeratosis
  • Epidermal atrophy
  • Dermal mucin deposition
  • Liquefactive degeneration of the basal layer of the epidermis and vacuolization
  • Thickening of the basement membrane
  • Pigment incontinence
  • Mononuclear cell infiltration at dermo-epidermal junction
  • Superficial, perivascular, and perifollicular areas (due to mononuclear cell inflammatory infiltrate)
SLE dermatitis subtype Specific microscopic findings
Acute cutaneous lupus erythematosus
  • Lymphohistiocytic infiltrate in the superficial dermis20482683
Subacute cutaneous lupus erythematosus
  • Less follicular plugging and hyperkeratosis in comparison with dischoid lupus erythematosus
  • Superficial appendageal and perivascular lymphocytic infiltration
  • Absence or minimal change of basement membrane thickening
Chronic cutaneous lupus erythematosus
  • Discoid lupus erythematosus :
    • Follicular plugging
    • Mononuclear cell infiltration near the dermal-epidermal junction, dermal blood vessels, and appendages
  • Lupus erythematosus tumidus:
    • Consisting of predominately CD3+/CD4+ lymphocytes
    • Focal interface changes
  • Lupus profundus (lupus panniculitis) :
    • Perivascular infiltrates of mononuclear cells plus panniculitis
    • Hyaline fat necrosis
    • Direct immunofluorescence: Immune deposits in the dermal-epidermal junction

Glomerulonephritis histo-pathology:

SLE nephritis subtype Light microscopy findings Electron microscopy/Immunofluorescence findings
Minimal mesangial lupus nephritis (class I) -
  • Mesangial immune deposits
Mesangial proliferative lupus nephritis (class II)
  • Mesangial hypercellularity (of any degree)
  • Mesangial matrix expansion
  • Isolated subepithelial or subendothelial deposits
Focal lupus nephritis (class III)
  • Active or inactive endocapillary or extracapillary segmental glomerulonephritis
  • Involvement of glomeruli < 50%
  • Immune deposits in the subendothelial space of the glomerular capillary and mesangium
  • Fibrinoid necrosis and crescents in glomeruli
  • Tubulointerstitial or vascular abnormalities
Diffuse lupus nephritis (class IV)
  • Endocapillary glomerulonephritis
  • Extracapillary glomerulonephritis
  • Mesangial abnormalities
  • Involvement of glomeruli > 50%
  • Subendothelial deposits specially during the active phase
  • Diffuse wire loop deposits with little or no glomerular proliferation
Lupus membranous nephropathy (class V)
  • Diffuse thickening of the glomerular capillary wall
  • Immunofluorescence or electron microscopy
  • Global or segmental subepithelial immune deposits
Advanced sclerosing lupus nephritis (class VI)
  • Global sclerosis
  • Involvement of glomeruli > 90%
  • Global or segmental subepithelial immune deposits

Synovial histopathology

  • Nonspecific histopathologic findings
  • Superficial fibrin-like material
  • Local or diffuse synovial cell lining proliferation
  • Vascular changes:
  • Perivascular mononuclear cells
  • Lumen obliteration
  • Enlarged endothelial cells
  • Thrombi

Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology

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