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Rheumatoid Arthritis: Clinical Significance Of Its Extra-articular Manifestations And Laboratory Investigations

Updated on February 13, 2014

Scleritis In Rheumatoid Arthritis

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Clinical Presentations Of Rheumatoid Arthritis

The extra-articular manifestations in rheumatoid arthritis include manifestation on the skin, eyes, respiratory manifestations and cardiovascular system. It is important to know the procedure to detecting and diagnosing Rheumatoid Arthritis which is done in the medical laboratory.

Skin: Painless and non tender subcutaneous nodules ranging in size from a few millimeters to a few centimeters develop around the extensor aspects of the elbow and other subcutaneous bony surfaces and over tendons in 20- 30% of cases. They are almost always associated with a positive serology. They persist for considerable periods. Other skin lesions are Raynaud’s phenomenon, vasculitis of the nail beds, non-healing ulcers of the fingers, palmar erythema and hyperhydrosis of the extremities.

Eyes: Ocular lesions develop in a few cases and these can become disabling. Scleritis is common. In some cases, it becomes nodular. In necrotizing scleritis, the nodules degenerate and the underlying dark uvea imparts a blue colour. Sometimes the sclera may be thickened due to granuloma formation. Perforation of the sclera leads to prolapsed of the uvea and eventual rupture of the globe (Scleromalacia perforans).

In the cornea, band karatopathy may develop. This is more frequent in Still’s disease. Iritis is rare. Presence of iritis is more suggestive of seronegative spondylarthroses.

Respiratory manifestations: These may occur in some cases. Cricoarytenoid arthritis manifests as dysphonia, stridor or dyspnea. Recurrent pleural effusion may occur which is usually unilateral. Rheumatoid nodules may develop in the lungs and these rarely cavitate. Interstitial fibrosis may develop and this may be indistinguishable from the idiopathic type.

Caplan’s syndrome is a special phenomenon occurring in subjects with rheumatoid disease who develop pneumoconiosis. Large coalescing nodules develop in the lungs. These are demonstrable by X-rays.

Cardiovascular system: It is only rarely involved. Lesions include pericarditis, aortic regurgitation and conduction defects.

Neuropathy: Neurological involvement is not uncommon in chronic cases.

  1. Entrapment neuropathy such as carpal tunnel syndrome and tarsal tunnel syndrome are not uncommon
  2. Symmetrical polyneuropathy develops which improves with treatment. Mononeuritis multiplex develops in some cases.
  3. In severe cases of rheumatoid disease (malignant rheumatoid arthritis) foot drop, and wrist drop may develop. These are generally resistant to treatment.

Secondary amyloidosis is a late complication in some cases of generalized rheumatoid disease.

Synovial Fluid Aspiration

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Radiology Of Rheumatoid Arthritis

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Laboratory Investigations

Erythrocyte sedimentation rate is markedly raised in the active disease and may exceed 100 mm/hr in the majority. Normochromic normocytic anemia, iron deficiency anemia or rarely hemolytic anemia may be present in acute phase. Serum protein electrophoresis may show elevation of alpha-2 and gamma-globulins.

Serology: Rose Waalar test, latex fixation test or bentonite flocculation. Rheumatoid factor is positive in 80% of adults with rheumatoid arthritis. A differential agglutination titre of 16 and above is diagnostic. In 20% of cases, LE cells and antinuclear antibodies may be demonstrable.

Radiology: Characteristic lesions which have been graded from I to IV are seen on radiological study.

Grade I: Soft tissue swelling with/without juxtaarticular osteoporosis.

Grade II: Narrowing of joint space due to cartilage destruction.

Grade III: Erosions which may be of 2 types: (1) surface erosion of joint margins and (2) Cystic erosions of the bone shaft.

Grade IV: Marked irregularity of articular surfaces with subluxations and secondary degenerative changes. Bony ankylosis occurs only very rarely.

Synovial fluid aspiration: This reveals a turbid fluid with low viscosity and poor mucin clot. The white cell count in the fluid exceeds 1500/cmm. Complement levels are low. The protein content is high and the electrophoretic pattern approaches that of serum.

© 2014 Funom Theophilus Makama

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