Rheumatoid Arthritis – Extra Articular Features

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These tend to be more numerous and severe in those with high

titres of rheumatoid factor in blood. Three major pathological phenomena

dominate the disease.

1. Inflammation of membranes

2. Nodule formation

3. Vasculitis.

i) Rheumatoid Nodules:

Subcutaneous and intracutaneous nodules are the hall mark of the

disease in ¼ th of patients. They are firm, non-tender swellings that

occur on the extensor surface of the fore arm and olecranon sites, where

repeated minor trauma could initiate their formation. They may also

develop in many other tissues including eye (Scleromalacia), pleura,

pericardium, parenchyma of lungs and heart.

ii) Haematological manifestation:

1. Anaemia:

Moderate normochromic normocytic anaemia is a finding in active

RA. Factors that are related to the inflammatory process probably

contribute to this anaemia. There may be ineffective erythropoiesis and

red blood cell survival is reduced. Iron binding capacity is typically

reduced in active rheumatoid arthritis.

2. Thrombocytosis, Leukopenia is a finding in patients with Felty’s

Syndrome.

iii) Vasculitis:

Intimal hyperplasia of the small terminal digital vessels causes very

limited cutaneous lesions (Nail fold infarcts, rashes, splinter

haemorrhages). In contrast severe life threatening tissue infection may

develop when there is involvement of large blood vessels by

leucocytoclastic or necrotizing vasculitis.

iv) Lung involvement:

1. Pleurisy:

The fluid has more protein, low glucose, low complement levels

and is typically positive for RA factor.

2. Nodules (Caplan syndrome):

More in upper than lower zones. Cavitation may occasionally lead

to haemoptysis.

3. Pulmonary fibrosis:

It causes progressive dyspnoea, clubbing of fingers, fine late

inspiratory crepitations.

4. Obliterative Bronchiolitis:

Manifesting with an acute onset of breathlessness. Many patients

have evidence of airway obstruction. Bronchiectasis also appears to

be more common.

v) Cardiac involvement:

1. Pericardial effusion can be found by ultra-sonography in

patients with seropositive nodular disease. Constrictive

pericarditis is more common and presents with dyspnoea, right

sided heart failure, peripheral oedema.

2. Valvulitis: Granulomatous thickening of the cusps of the aortic

valve occurs more frequently than in the mitral valve, rarely

producing incompetence.

vi) Eye involvement:

Common in RA and may be due to localized tissue

involvement.

1. Episcleritis:

Appears as a raised lesion in the anterior sclera with

hyperaemia of the deeper layers.

2. Scleritis:

Is less common and may lead to progressive thinning of the

sclera (scleromalacia) and even perforation.

3. Keratoconjunctivitis sicca (dry eyes) due to secondary

Sjogren’s syndrome.

4. Corneal melting is a rare manifestation. Clinical features are

pain, redness and blurred vision with corneal thinning.

vii) Peripheral Nerve involvement:

Peripheral neuropathies can be produced by proliferating

synovium causing compression of nerves. A mild glove and

stocking sensory neuropathy is relatively common in RA.

viii) Muscle involvement:

Is attributed to the reflex inhibition and wasting resulting

from severe joint pain.

ix) Liver pain:

There may be mild hepatosplenomegaly and asymptomatic

elevation of the serum alkaline phosphatase.

x) Bone involvement:

Juxta – articular osteoporosis is an early feature. A small

proportion of patients may develop osteomalacia.

xi) Felty’s syndrome:

Lymphadenopathy is common. It is more obvious in

patients with Felty syndrome (Rheumatoid arthritis, Splenomegaly,

Leucopenia). Other features include anaemia, thrombocytopenia,

persistent vasculitic leg ulceration, cutaneous pigmentation, weight

loss and recurrent infection.

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