Systemic lupus erythematosus (SLE): Clinical

Systemic Lupus Erythematosus, or lupus, is an autoimmune disease, where essentially any tissue or organ can be the target of inflammation.

Often there are periods of illness, called flares, and periods of remission during which there are few symptoms.

The diagnosis of lupus is made when 4 or more out of 11 criteria are met.

The first three have to do with the skin.

The first is a malar rash, sometimes just called a “butterfly rash”, which is a rash over the cheeks that spares the nasolabial folds and appears after sun exposure.

Second is a discoid rash, which is chronic erythematous rash in sun-exposed areas like the arms and legs that are plaque-like or patchy redness and can scar.

Third, is a general photosensitivity of the skin — essentially a catch-all category for other rashes that happen to sun-exposed areas — typically only lasting a couple of days.

Lupus can also damage the inner membrane or mucosa of various tissues, so the fourth criteria is ulcers in the mouth or nose.

The fifth criteria is serositis which is inflammation of the serosa, which is like the outer membrane of an organ or tissue.

It can manifest as pleuritis, which is inflammation of the lining around the lungs and chest cavity; as pericarditis, which is inflammation of the lining of the heart; or as peritonitis, which is inflammation of the lining of the abdomen.

Now, in addition to pericarditis, it’s worth noting that lupus can also cause inflammation of the myocardium, leading to myocarditis, or the endocardium, leading to Libman-Sacks endocarditis, where clumps of fibrin and immune cells form vegetations on the mitral valve.

The sixth criteria is arthritis, and two or more joints have to get inflammed to meet the criteria.

The seventh criteria is evidence of kidney damage based on protein or cells in the urine.

It’s generally caused by lupus nephritis, which is a type of glomerulonephritis due to immune complex deposition along the glomerular basement membrane.