Systemic lupus erythematosus

Dermatological manifestations

Examination of the skin and mucous membranes is of paramount importance, as skin changes serve as reliable markers of systemic connective tissue pathologies. In systemic lupus erythematosus, the most recognizable symptom is the «butterfly» erythema, which is localized on the bridge of the nose and spreads to both cheeks.

The basis of such skin rashes is local inflammation of the dermal microvessels, which is frequently accompanied by hemorrhages. Therefore, along with erythema, patients may exhibit a pronounced hemorrhagic syndrome manifesting as small punctate hemorrhages (petechiae) and more extensive bruises (ecchymoses).

Morphological substrate of autoimmune damage

The morphological picture in SLE is predominantly of an inflammatory and destructive nature. The central link in the pathogenesis is vascular changes, or autoimmune vasculitis.

• Evolution of vascular damage: the process begins with mucoid swelling of the vessel walls, transitions into fibrinoid swelling, and culminates in fibrinoid necrosis. These destructive vasculitides primarily affect small-caliber vessels — capillaries and arterioles.
• Surrounding tissues: perivascular and pericellular edema forms around the affected vessels, and microhemorrhages occur. When the microvasculature of the brain is involved, this causes severe neurological symptoms.
• Cellular infiltration: target tissues are actively infiltrated by lymphocytes, macrophages, and plasma cells. This process is typically patchy, meaning non-uniform and focal in character.

Specific findings and systemic changes

In addition to universal signs of autoimmune inflammation, systemic lupus erythematosus features a number of unique (pathognomonic) morphological findings detected upon tissue microscopy:

1. Hematoxylin bodies — specific structures representing degraded nuclear material from damaged cells.
2. «Onion skin» phenomenon — characteristic concentric thickening of the walls of small arteries in the spleen.
3. Lupus nephritis — severe damage to the renal filter accompanied by pronounced structural changes in the glomerular basement membranes.
4. Aseptic endocarditis (also known as Libman-Sacks endocarditis) — inflammation of the endocardium occurring without the involvement of infectious agents.

At the systemic level, the disease is accompanied by plasmacytic transformation, pronounced lymphoid tissue hyperplasia, and a propensity for polyserositis — combined inflammation of the serous membranes, including the pleura, pericardium, and peritoneum.

Differential diagnosis

One of the complex clinical challenges is differentiating SLE from genetically determined syndromes (e.g., May-Hegglin, Fechtner, Epstein syndromes) caused by mutations in the MYH9 gene.

The similarity lies in the fact that these hereditary anomalies may also present with a combination of decreased blood platelet levels (causing bleeding tendencies) and severe kidney damage (nephropathy).

Criteria for excluding an autoimmune nature (and consequently SLE) in such controversial cases include:

• Complete absence of laboratory markers of systemic immune inflammation.
• Absolute ineffectiveness of glucocorticosteroids, which provide a pronounced therapeutic response in true lupus.

Class and exam questions

What else to study on this topic

• Stages of vasculitis development: from mucoid swelling to fibrinoid necrosis.
• Features of cellular inflammatory infiltration of tissues in systemic pathologies.
• Changes in glomerular basement membranes in lupus nephritis.
• Spectrum of genetic anomalies involving the MYH9 mutation (Fechtner, May-Hegglin syndromes) in the differential diagnosis of SLE.
• Outcomes of chronic autoimmune inflammation: sclerosis of vessels and organ stroma.

Other topics in the "Additional Topics" section

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