Understanding and Differentiating Lupus from Other Diseases

Lupus is an autoimmune disease that is heterogeneous in character. Which means that it may have quite a different signs and symptoms in individuals. It is predominantly a disease of women of childbearing age. But the symptoms may be anything from skin rashes, fatigue, neurological changes, miscarriage, joint pains to name the few. So the question arises that how to differentiate it based on the symptoms, and what are the other common disease that can be confused with lupus?

First, we present the list of main signs that are present in lupus, these criteria are recommendations of American College of Rheumatology. Though the final diagnosis would be done by a medical specialist, it is worth knowing all the common signs found in lupus. A person maybe considered to have lupus if any of the four out of eleven signs are present(1). Below is the list of those eleven criteria with explanation and additional information about them;

1. Malar rash- Reddish skin rash that mainly covers cheekbone (malar), it takes the shape of butterfly thus also called butterfly rash, it tends to spare the nasolabial folds
2. Discoid rash- round and raised pink rashes, they are often multiple, slightly raised above the skin, mostly found in the upper half of the body, they are commonly found on scalp (with hair loss at place of rash), may form flakes or crust, they may leave scar or pigmentation mark on healing, usually found in one-fifth cases of lupus
3. Photosensitivity- development of skin rashes on exposure to skin, some people may have flares (worsening of other symptoms) of lupus on long exposure to sunlight(2)
4. Oral ulcers-  oral ulcers in lupus tend to be painless
5. Arthritis- (Non-erosive: Jaccoud's arthropathy) painful condition of the joints caused due to inflammation of capsule of joints. Presentation of joint pains is one of the most common signs of lupus, in theinitialstage, it is not uncommon to confuse lupus with other joint related diseases. Lupus generally involves pain in small joints of hand or feet
6. Serositis- is inflammation of the outer covering of lungs or heart. If outer covering of lungs is inflamed it is called pleuritis and is characterized by pain while breathing, if it affects the outer covering of heart then there could be pain in chest not related to breathing and changes in ECG,it is called pericarditis(3)
7. Renal disorder- may be difficult to know at anearly stage, but in later stages, there may be unexplained swelling of feet and ankles, elevated blood pressure, changes in urine color. Lab examination may show ahigh content of proteins, cell casts. It may develop in up to 50% of cases and may give rise to serious complications(4)
8. Neurological disorder- it may manifest in 25-75% of cases in the form of seizures, anxiety, depression, or even psychosis.
9. Hematological disorder - may present as multiple cytopenias (deficit of various blood cells), like anemia (fewer red cells), lymphopenia, leukopenia, or even thrombocytopenia (4)
10. Immunological disorder-  lab analysis may show; Anti-DNA antibodies, Anti-Sm antibodies, Antiphospholipid antibodies
11. Anti-nuclear antibody- a diagnostic laboratory test

Disease that may mimic lupus

As one can see that lupus is a multi-organ disease, thus it can be confused with too many ailments. Below is the list of diseases that are often confused with lupus or vice versa.

Rheumatoid arthritis (RA)

It is perhaps the most commonly confused disease with lupus, the reason being too many commonalities between them. In initial phase it may not be possible to differentiate them at all, RA often presents as pain in joints along with fatigue and skin rashes. Quite like lupus, flares are also characteristic of RA, and RA is a more widespread illness. But lupus may be differentiated if there are some more typical signs present like a malar rash. In lupus joint pain mostly starts with smaller joints of hands and feet. Further lupus rarely causes joint deformation while in long term RA often deforms the affected joints. But final differentiation is often based on a test of a wide range of antibodies that are more characteristic of lupus, and radiography of joints (RA often shows symmetrical deformations).

Antiphospholipid syndrome

A disease characterized by pain in limbs, chest, shortness of breath, loss of fetus due to arterial or venous thrombosis. Women suffering from it are at increased risk of miscarriage and pregnancy related complications. Blood test for antiphospholipid antibodies would generally confirm the diagnosis(5).

Systemic sclerosis

A very poorly understood medical condition, but may greatly resemble lupus in symptoms. Skin rashes and joint pains are common; it is a multi-organ disease with the varied clinical picture. It may affect heart, lung, and kidneys. It may not be possible to differentiate it from lupus without specific blood tests (checking for specific antibodies to confirm the diagnosis).

Mixed connective tissue disease (MCTD)

An autoimmune disease that may greatly resemble lupus in symptoms. Characterized by fatigue, general feeling of unwell, skin rashes and joint pains, may affect other internal organs. It is not possible to differentiate this disease from lupus just by manifestations. The only way to confirm the diagnosis is a blood test for specific antibodies (anti-RNP antibody) (6).

HIV and CMV

Both are infectious viral diseases, but with the different clinical picture in various people, fatigue, night time sweating, swelling of lymph nodes, muscular pain and general malaise are common. It is possible that some people may develop skin rashes too. Symptoms are usually very vague, and the only way to diagnose is a blood test.

Hematological malignancies

They may also be confused with lupus, with the similar presenting picture. Hematological malignancies may initially start with unexplained fatigue, illness, rashes, anemia or cytopenias. They have to be diagnosed early for effective treatment, else can be fatal. They are differentiated by using various blood tests (absence of antibodies), and bone marrow histology.

Glomerulonephritis

It is essentially a disease of the kidney with symptoms ranging from swelling of extremities to changes in urine color and consistency. In some people lupus may present predominantly with the symptoms related to the kidney disease, thus making the diagnosis difficult. Clinically such cases may not be possible to differentiate, the only way to confirm the diagnosis is a blood test or renal biopsy.

Fibromyalgia

It is poorly known disease, nor the causes of this disorder are clear. Fibromyalgia would generally present with muscular aches and fatigue, rather than joint pain or skin rashes. Diagnosis can be confirmed through a blood test (absence of antibodies).

Thus what we see that there are the whole bunch of diseases that may present itself like lupus, making differentiation based on signs and symptoms quite impossible. Usually, doctors may require several antibody tests to come to any conclusion. Due to changes in lifestyle and diet, along with rising use of self-treatment in some parts of the world, more and more diseases are having an atypical presentation. It is not rare that person suffering from lupus may not have the classic malar rash or pain in joints. The only way for early diagnosis is the laboratory analysis by the medical specialist.

References

1. Manson JJ, Rahman A. Systemic lupus erythematosus. Orphanet J Rare Dis. 2006 Mar 27; 1:6.

2. Emerit I, Michelson AM. Mechanism of photosensitivity in systemic lupus erythematosus patients. Proc Natl Acad Sci U S A. 1981 Apr;78(4):2537–40.

3. Man BL, Mok CC. Serositis related to systemic lupus erythematosus: prevalence and outcome. Lupus. 2005;14(10):822–6.

4. COJOCARU M, COJOCARU IM, SILOSI I, VRABIE CD. Manifestations of Systemic Lupus Erythematosus. Mædica. 2011 Oct;6(4):330–6.

5. What Are the Signs and Symptoms of Antiphospholipid Antibody Syndrome? - NHLBI, NIH [Internet]. [cited 2017 Sep 4]. Available from: https://www.nhlbi.nih.gov/health/health-topics/topics/aps/signs

6. Alarcón-Segovia D, Cardiel MH. Comparison between 3 diagnostic criteria for mixed connective tissue disease. Study of 593 patients. J Rheumatol. 1989 Mar;16(3):328–34.