Rheumatology & Connective Tissue

Anti-dsDNA antibodies are highly specific (100%) for diagnosis of SLE. Its level correlates with lupus activity.

Explanation: Malar rash in SLE: Fixed erythema, flat or raised, sparing the nasolabial folds

Ref: Davidson 23rd; P-1004 , box : 24.34

Urethritis + arthritis + conjunctivitis = reactive arthritis
Reactive arthritis >>>> the Pt. can’t see, can’t pee, can’t bend the knee

Ref: Davidson 23rd; P-1038

Stem Breakdown:

Fever, arthritis, and a malar rash: These are classic symptoms of systemic lupus erythematosus (SLE), an autoimmune disease that can affect multiple organs.
Positive ANA and anti-dsDNA antibodies: These antibodies are highly specific for SLE, especially anti-dsDNA, which correlates with disease activity.
Option Analysis:

A) Rheumatoid arthritis: Rheumatoid arthritis primarily causes symmetric polyarthritis, particularly affecting the small joints of the hands and feet. It is not typically associated with a malar rash or positive anti-dsDNA antibodies.
B) Systemic lupus erythematosus (SLE): This is the correct diagnosis. Davidson and Harrison both emphasise that SLE is a systemic autoimmune disease characterised by a wide range of clinical features, including the malar (butterfly) rash, arthritis, renal involvement, and positive ANA and anti-dsDNA antibodies.
C) Dermatomyositis: Dermatomyositis is an inflammatory myopathy that causes muscle weakness and characteristic skin findings (e.g., heliotrope rash, Gottron’s papules), but it does not cause the malar rash or positive anti-dsDNA antibodies seen in SLE.
D) Sjögren’s syndrome: Sjögren’s syndrome is characterised by dry eyes and dry mouth due to autoimmune destruction of the salivary and lacrimal glands. It does not typically present with a malar rash or positive anti-dsDNA antibodies.

Explanation: Gout is the most common inflammatory arthritis in men and in older women. It is caused by deposition of monosodium urate monohydrate crystals in and around synovial joints.

Ref: Davidson 23rd; Box- 24.55

Explanation: Osteoarthritis (OA) is by far the most common form of arthritis and is a major cause of pain and disability in older people. It is characterised by focal loss of articular cartilage, subchondral osteosclerosis, osteophyte formation at the joint margin, and remodelling of joint contour with enlargement of affected joints.

Ref: Davidson 23rd; P-992 , box : 24.10

Explanation: Felty’s syndrome is a rare complication of seropositive RA in which splenomegaly occurs in combination with neutropenia and thrombocytopenia

Explanation: Osteophyte formation is characteristic of osteoarthritis, not rheumatoid arthritis. Davidson describes rheumatoid arthritis (RA) as a chronic autoimmune disease with symmetrical joint involvement, morning stiffness, and joint erosions visible on imaging. Harrison adds that RA is associated with systemic inflammation and can lead to joint deformity if untreated.

Raynaud’s phenomenon is digital ischaemia induced by cold and emotion. It has three phases 
•     pallor: due to digital artery spasm and/or obstruction
•     cyanosis: due to deoxygenation of static venous blood
(this phase may be absent)
•    redness: due to reactive hyperaemia.

Anti-CCP antibodies are associated with rheumatoid arthritis (highly specific)

Targets for antiphospholipid antibodies
 β2 -glycoprotein 1
 Protein C  Annexin V  Prothrombin (may result in haemorrhagic presentation)

Ref: Davidson 23rd; P-1015

Pulmonary hypertension is the leading cause of death in patients with systemic sclerosis, according to Davidson. It results from vascular damage and fibrosis within the lungs. Harrison explains that early detection and treatment of pulmonary hypertension are essential to improving survival in systemic sclerosis patients.

Ref: Davidson 23rd; P-982

Ref: Davidson 23rd; P-997

Infections are the leading cause of death in patients with systemic lupus erythematosus (SLE), as noted by Davidson. The immunosuppressive therapies used to control lupus, such as corticosteroids and cytotoxic drugs, increase the risk of severe infections. Harrison adds that while renal failure was once a leading cause of mortality in SLE, advances in treatment have improved long-term outcomes, with cardiovascular complications and infections now being more common causes of death.

Explanation: Tests for ACPA are positive in about 70% of cases and are highly specific for RA, occurring in many patients before clinical onset of the disease

Aphthous oral lesions, genital ulcers and hypopyon suggest Behçet’s syndrome.

Answer: A
Explanation: The "butterfly" or malar rash is a hallmark feature of systemic lupus erythematosus (SLE), described in both Davidson and Harrison. This rash typically spares the nasolabial folds and is often triggered by sun exposure. SLE is a multisystem autoimmune disease, and skin manifestations like the malar rash are part of the diagnostic criteria.