A young lady with increasing shortness of breath over many months. Keeps birds at home. Hypersensitivity pneumonitis?
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Normal heart size and shape. Normal pleurae and pericardium. No bone lesions.
Mediastinum: Multiple small non-calcified nodes are present.
Lungs: There are multiple nodules present in all segments of both lungs. Nodules are well defined, centrilobular in location. No cavitation of the nodules seen. In addition, there are areas of more conglomerate mass formation seen particularly in the upper zones. These are associated with changes of lung distortion and fibrosis. No subpleural reticulation or interlobular septal thickening is noted. Some areas of air trapping / mosaic attenuation are noted bilaterally
2 case questions available
MICROSCOPIC DESCRIPTION: 1,2. Sections of the lung wedges show preserved architecture. There is non-necrotising granulomatous inflammation with many granulomas. They follow lymphatic distribution around the broncho vascular bundles, in the interlobular septa and subpleural. They comprise nodular aggregates of epithelioid histiocytes with multinucleated giant cells. The granulomas are well-defined and they are surrounded by some fibrosis and occasional lymphocytes. The intra-alveolar spaces are unremarkable. There is no evidence of organising pneumonia. No neutrophils are seen. The blood vessels show no evidence of vasculitis. No evidence of malignancy is identified. The features are not typical for psittacosis. The Gram stain shows no bacteria. The Grocott stain shows no fungi. The Ziehl-Neelsen stain shows no acid-fast bacilli.
DIAGNOSIS: R upper and mid lobe wedges: Non-necrotising granulomatous inflammation, which could be consistent with sarcoidosis in the appropriate clinical setting.
This case represents pulmonary and mediastinal manifestations of sarcoidosis, which is a non-caseating granulomatous multisystemic disease.
Relevant aspects of this condition:
- although any age group may be involved, it is usually seen in patients between 20 and 40 years of age
- approximately 50% of patients are asymptomatic
- histopathology study shows multiple granulomas in a characteristic lymphatic and perilymphatic distribution, typically non-caseating and coalescent. Sarcoid granulomata are distributed mainly along the lymphatics in the bronchovascular sheath and, to a lesser extent, in the interlobular septa and subpleural lung regions
- sarcoidosis is often termed the "great mimicker" as there is a vast range of HRCT presentations
- lymphadenopathy is present in 80-90% of patients: generally tends to be symmetrical with hilar and middle mediastinal involvement
Subacute hypersensitivity pneumonitis develops when hypersensitivity pneumonitis continues beyond the acute phase (i.e. continues for weeks to months). While some publications suggest the disease to needs to prevail for between 1-4 months to fall into this category, it is important to realise that the terms acute, subacute and chronic lie on a continuum.
Symptoms are similar to, but less severe than, those in the acute phase. Symptoms are often prolonged over weeks to months. Patients may experience recurrent episodes of acute symptoms superimposed on a background of deteriorating respiratory function.
Subacute hypersensitivity pneumonitis usually results from intermittent or continuous exposure to low doses of antigen and is histologically characterised by the presence of cellular bronchiolitis, non-caseating granulomas, and bronchiolocentric interstitial pneumonitis with a predominance of lymphocytes.
There can be considerable overlap in HRCT chest findings of acute and subacute hypersensitivity pneumonitis. Typically described features in the subacute phase include:
- ground-glass and nodular opacities in a centrilobular distribution
- heterogeneous or small nodular opacities: with a predominance for the mid to lower lung zones
- patchy air space opacification
- irregular linear opacities are less common on CT
- air trapping on expiratory imaging is a non-specific but helpful ancillary finding - this reflects associated bronchiolitis, this can in turn lead to a mosaic attenuation pattern