Page 388 - Concise Pathology for Exam Preparation ( PDFDrive )

13 The Lung 373

• Constitutional signs and symptoms include fever, fatigue, weight loss, anorexia and
night sweats
• May present with peripheral lymphadenopathy, cutaneous lesions, eye involvement or
hepatosplenomegaly
• Chronic progressive course or alternating periods of remission (spontaneous or steroid
induced) and activity is typical
• Most resolve with minimal or no residual manifestations
• Most succumb to progressive pulmonary fibrosis and cor pulmonale

Q. Write briefly on hypersensitive pneumonitis.
Ans. Hypersensitivity (allergic) pneumonitis is an immunologically mediated response to
an extrinsic antigen involving, initially immune complex (Type III) and later granulomatous
(Type IV hypersensitivity). It includes
• Farmer lung caused by moldy hay containing actinomycetes (external antigen)
• Pigeon breeder’s disease or bird fancier’s disease caused by proteins from serum,
excreta or feathers of birds
• Humidifier or air-conditioner lung caused by thermophilic bacteria in heated water
reservoirs

Clinical Features
• Acute form: Recurring episodes of fever, dyspnoea, cough and leukocytosis
• Chronic form: Signs of progressive respiratory failure, dyspnoea, cyanosis and reduced
lung compliance

X-Ray
Diffuse or nodular infiltrates

Pulmonary Function Tests

These are indicative of a restrictive disorder

Morphology
Histological changes are mainly seen in bronchioles and include
• Interstitial pneumonitis consisting of lymphocytes, plasma cells and macrophages
• Noncaseating granulomas
• Interstitial fibrosis and obliterative bronchiolitis (in late stage)

Q. Write briefly on pulmonary eosinophilia.

Ans. Pulmonary eosinophilia includes several entities, eg, acute eosinophilic pneumo-
nia with respiratory failure, secondary eosinophilia and idiopathic chronic eosinophilic
pneumonia.

1. Acute eosinophilic pneumonia with respiratory failure: It is a steroid-responsive dis-
ease which presents with hypoxaemia, fever, dyspnoea and pulmonary infiltrates. The
bronchoalveolar lavage fluid contains more than 25% eosinophils and histopathology
shows extensive alveolar damage with eosinophilic infiltration.
2. Secondary eosinophilia: Occurs secondary to bacterial, fungal and parasitic infections,
hypersensitivity pneumonitis, drug allergies, asthma, allergic bronchopulmonary asper-
gillosis and Churg-Strauss syndrome.
3. Idiopathic chronic eosinophilic pneumonia: As a diagnosis of exclusion, it responds to
steroid therapy and manifests with cough, fever, dyspnoea, night sweats and weight

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