From the Guidelines
The workup of a mosaic pattern on CT chest should begin with a thorough clinical evaluation, including a detailed history focusing on respiratory symptoms, exposures, and risk factors, followed by high-resolution CT imaging during inspiration and expiration to differentiate between air trapping and vascular pathology, as recommended by the most recent study 1. This pattern represents areas of differing lung density and can indicate several conditions including small airways disease, pulmonary vascular disease, or interstitial lung disease.
- Initial testing should include:
- Pulmonary function tests with diffusion capacity
- A six-minute walk test to assess functional impairment
- Additional studies may include:
- Laboratory testing, such as complete blood count, comprehensive metabolic panel, and specific serologies based on clinical suspicion
- Bronchoscopy with bronchoalveolar lavage to rule out infection or evaluate for cellular patterns suggestive of specific diagnoses
- In cases where diagnosis remains unclear, surgical lung biopsy may be required, as suggested by 1 and 1. This comprehensive approach is necessary because the mosaic pattern is a radiographic finding rather than a specific diagnosis, and determining the underlying cause is essential for appropriate treatment, as highlighted in 1. The presence of a mosaic pattern on CT chest can be associated with various conditions, including chronic thromboembolic pulmonary hypertension (CTEPH), pulmonary arterial hypertension (PAH), and interstitial lung disease, as discussed in 1 and 1. Therefore, a thorough clinical evaluation and additional testing are crucial to determine the underlying cause of the mosaic pattern and guide appropriate treatment, as recommended by the most recent study 1.
From the Research
Mosaic Pattern on CT Scan of the Chest
The workup for a mosaic pattern on a computed tomography (CT) scan of the chest involves considering various differential diagnoses, as this pattern can be caused by different categories of disease, including small-airway disease, vascular lung disease, and infiltrative disease 2.
Causes of Mosaic Attenuation Pattern
- Small-airway disease: obliterative bronchiolitis and panlobular emphysema may present with decreased attenuation pattern, while obliterative bronchiolitis, chronic pulmonary embolism, and hypersensitivity pneumonitis (HP) may manifest with mosaic attenuation pattern 3.
- Vascular lung disease: chronic thromboembolic pulmonary hypertension (CTEPH) can cause a mosaic attenuation pattern (MAP) in chest CT, suggesting CTEPH 4.
- Infiltrative disease: various disorders can manifest the CT pattern of bilateral pulmonary nodules together with mosaic attenuation, including diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH), metastatic/multifocal cancer, bronchiolitis, and interstitial lung disease 5.
Diagnostic Approach
To distinguish among these categories, additional CT findings and clinical history should be considered 2. For example, a previous diagnosis of an obstructive lung disease and peribronchial nodular distribution on CT may increase the likelihood of DIPNECH 5. The frequency of a mosaic pattern of lung attenuation on CT scans also varies among patients with pulmonary artery hypertension (PAH) of different causes, with a higher frequency seen in patients with PAH due to vascular disease 6.
Key Findings
- A mosaic attenuation pattern on CT scan can be caused by various diseases, including small-airway disease, vascular lung disease, and infiltrative disease.
- The diagnostic approach should involve considering the patient's clinical history and additional CT findings to distinguish among these categories.
- The frequency of a mosaic pattern of lung attenuation on CT scans varies among patients with PAH of different causes.