Page 511 - Textbook of Pathology, 6th Edition

lipid in it. The condition can occur at any age from infancy 3. SYSTEMIC LUPUS ERYTHEMATOSUS. Patients with 495
to old age. systemic lupus erythematosus (SLE) commonly develop
some form of lung disease during the course. The most
ETIOPATHOGENESIS. The etiology and pathogenesis of common manifestation of SLE is pleurisy with small amount
alveolar proteinosis are unknown. A number of possibilities of pleural effusion that may contain LE cells. Other
have been suggested: pulmonary lesions in SLE are interstitial pneumonitis,
Since the alveolar material is combination of lipid and
protein, it is not simply an overproduction of surfactant. pulmonary haemorrhage and vasculitis.
Alveolar proteinosis may have an occupational etiology 4. SJÖGREN’S SYNDROME. Patients with Sjögren’s
as seen in patients heavily exposed to silica. syndrome often have rheumatoid arthritis and associated
It may have an etiologic association with haematologic pulmonary changes. Involvement of the bronchial mucous
malignancies. gland by a process similar to that in the salivary glands can
There may be defective alveolar clearance of debris. lead to inadequate bronchial clearance and repeated
infections.
MORPHOLOGIC FEATURES. Grossly, usually both
lungs are involved, particularly the lower lobes. The lungs 5. DERMATOMYOSITIS AND POLYMYOSITIS.
are heavier with areas of consolidation. Sectioned surface Interstitial pneumonitis and interstitial fibrosis commonly
exudes abundant turbid fluid. accompany dermatomyositis and polymyositis.
Histologically, the hallmark of the condition is presence 6. WEGENER’S GRANULOMATOSIS. Wegener’s
of homogeneous, granular, eosinophilic material which granulomatosis is an necro-inflammatory lesion having
stains brightly with PAS. Often, the material contains 4 components—granulomas of the upper respiratory tract,
cholesterol clefts. There is no significant inflammatory granulomas of the lungs, systemic vasculitis (page 403) and
infiltrate in the affected alveoli. Biochemically, the material focal necrotising glomerulonephritis. Localised or limited form
consists of serum proteins of low molecular weight, of the disease occurs in the lungs without involvement of
cholesterol and phospholipids similar to surfactant. other organs. Pulmonary involvement is in the form of single
Electron microscopy reveals that the material consists of or multiple granulomas.
necrotic alveolar macrophages and desquamated alveolar CHAPTER 17
epithelial cells. Microscopically, these granulomas have foci of fibrinoid
necrosis and intense infiltrate of lymphocytes, plasma cells
CLINICAL FEATURES. The condition is manifested and macrophages with scattered multinucleate giant cells.
clinically by dyspnoea, cough, chest pain, pyrexia, fatigue Besides necrotising granulomas, there is associated
and loss of weight. Chest X-ray shows confluent areas of vasculitis.
consolidation. Occasionally, alveolar proteinosis may recover
spontaneously but more often it is a fatal condition.
IDIOPATHIC PULMONARY FIBROSIS
ILD ASSOCIATED WITH Idiopathic pulmonary fibrosis is the most common form of
CONNECTIVE TISSUE DISEASES diffuse interstitial pneumonia and has bad prognosis The Respiratory System
compared with other forms of lung fibrosis. Diffuse inter-
A number of connective tissue diseases or collagen diseases
may result in chronic interstitial fibrosis and destruction of stitial fibrosis can occur as a result of a number of pathologic
blood vessels. These diseases are described in detail in entities such as pneumoconiosis, hypersensitivity
Chapter 4 but the lung involvement in important forms of pneumonitis and collagen-vascular disease. However, in half
collagen diseases is briefly considered here. the cases of diffuse interstitial fibrosis, no apparent cause or
underlying disease is identifiable. Such cases are included
1. SCLERODERMA (PROGRESSIVE SYSTEMIC under the entity ‘idiopathic pulmonary fibrosis’ in the United
SCLEROSIS). The lungs are involved in 80% cases of States and ‘cryptogenic fibrosing alveolitis’ in Britain.
scleroderma. Interstitial pulmonary fibrosis is the most
common form of pulmonary involvement. The disease PATHOGENESIS. The pathogenesis of idiopathic pulmo-
usually involves the lower lobes and subpleural regions of nary fibrosis is unknown and the condition is diagnosed by
the lungs and may lead to honeycombing of the lung. There excluding all known causes of interstitial fibrosis. However,
is increased risk of development of cancer of the lung in a few evidences point toward immunologic mechanism:
pulmonary fibrosis in scleroderma. 1. High levels of autoantibodies such as rheumatoid factor
2. RHEUMATOID ARTHRITIS. Pulmonary involvement and antinuclear antibodies.
in rheumatoid arthritis may result in pleural effusion, 2. Elevated titres of circulating immune complexes.
interstitial pneumonitis, necrobiotic nodules and rheumatoid 3. Immunofluorescent demonstration of the deposits of
pneumoconiosis (Caplan’s syndrome, page 490). The immunoglobulins and complement on the alveolar walls in
parenchymatous lesions in rheumatoid arthritis are most biopsy specimens.
commonly seen in the lower lobe. Necrobiotic nodules are
the most specific manifestations of rheumatoid disease and MORPHOLOGIC FEATURES. The lung involvement in
closely resemble the subcutaneous nodules commonly found idiopathic pulmonary fibrosis is often bilateral and
in rheumatoid arthritis. widespread.