| Disease | Description | Primary Structures Involved | Spatial Category | Characteristic CT Findings |
|---|
| Follicular Bronchiolitis | Reactive lymphoid hyperplasia with a peribronchiolar distribution; often associated with autoimmune diseases. | Bronchioles and peribronchiolar regions | Bronchioles | Multiple small centrilobular nodules, patchy air trapping, and mosaic attenuation (typically mid lung fields, reflecting small airways disease). |
| Pulmonary Lymphoid Hyperplasia | Hyperplastic lymphoid tissue within the lung that may lead to respiratory symptoms; often seen with small airways involvement. | Bronchioles and adjacent airway structures | Bronchioles | Localized or diffuse peribronchial nodules, predominantly in mid lung fields. |
| Pulmonary MALT Lymphoma | Low-grade B-cell lymphoma arising from bronchial-associated lymphoid tissue (BALT); typically indolent and often asymptomatic. | Bronchial-associated lymphoid tissue (BALT) and adjacent bronchioles | Bronchioles | Consolidative masses or nodules with air bronchograms; often with a lower lobe predominance. |
| Bronchiolitis Obliterans Organizing Pneumonia (BOOP/COP) | Organizing pneumonia with granulation tissue filling alveolar ducts and alveoli, frequently originating from the airways. | Alveolar ducts and alveolar spaces (airway origin) | Alveolar Spaces | Patchy peripheral consolidations and ground-glass opacities; often migratory and predominantly in peripheral or lower zones. |
| Lymphoid Interstitial Pneumonia (LIP) | Dense interstitial infiltrate of T cells, plasma cells, and histiocytes; associated with autoimmune disorders and immunodeficiency syndromes. | Lung interstitium and alveolar septa | Interstitium | Diffuse ground-glass opacities, interlobular septal thickening, and scattered cysts; often more prominent in the lower lung zones. |
| Nodular Lymphoid Hyperplasia (NLH) | Benign lymphoproliferative disorder presenting as single or multiple nodules; usually asymptomatic. | Lung parenchyma (often interstitial/peribronchial regions) | Interstitium | Multiple well-defined nodules, commonly seen in mid lung fields with a peribronchial distribution. |
| Lymphomatoid Granulomatosis (LG) | Rare B-cell lymphoma driven by Epstein–Barr virus; mimics pulmonary vasculitis with systemic signs. | Alveoli, interstitium, and small-to-medium-sized blood vessels | Interstitium | Multiple nodular opacities (often with cavitation) in a peribronchovascular distribution, typically centered in the mid lung fields. |
| Multicentric Castleman Disease (MCD) | Lymphoproliferative disorder driven by HHV-8; presents with systemic symptoms (fever, lymphadenopathy) and interstitial lung involvement. | Lymph nodes and lung interstitium (with extension into alveolar septa) | Interstitium | Diffuse interstitial thickening with ground-glass opacities and prominent lymphadenopathy, often in mid to lower zones. |
| Posttransplant Lymphoproliferative Disorder (PTLD) | Lymphoid proliferation due to immunosuppression after transplantation; can involve lung parenchyma. | Lung parenchyma including alveoli and interstitium | Interstitium | Multifocal nodules and consolidations with a random distribution across upper and lower lung fields. |
| AIDS-related Lymphoma (ARL) | Lymphoma associated with AIDS that primarily affects lung parenchyma. | Lung parenchyma and mediastinal/hilar lymph nodes | Interstitium | Solitary or multiple pulmonary nodules/masses with associated mediastinal/hilar lymphadenopathy; distribution is usually non-zonal. |
| Intravascular Lymphoma | Rare lymphoma characterized by proliferation of lymphoid cells within blood vessels; may involve lung parenchyma. | Pulmonary blood vessels embedded in the lung interstitium | Interstitium | Diffuse, subtle interstitial infiltrates with small nodular opacities, typically noted in the mid lung fields. |
| IgG4-Related Lung Disease | A systemic condition that causes interstitial pneumonia and lymphoid hyperplasia; involves bronchovascular and lymphatic structures. | Bronchovascular bundles and lung interstitium | Interstitium | Diffuse interstitial thickening, ground-glass opacities, and bronchovascular bundle thickening, most often in the mid lung zones. |
| Non-Hodgkin Lymphoma (NHL) | Primary pulmonary lymphoma that arises directly within lung tissue, typically manifesting as nodules or masses. | Lung parenchyma (commonly the interstitium) | Interstitium | Solitary or multiple masses/nodules with consolidative features; frequently with a lower lobe predominance. |
| Hodgkin Lymphoma | Although primarily a lymphatic malignancy, it can involve the lungs; typically presenting with lymphadenopathy and pulmonary infiltrates. | Mediastinal/hilar lymph nodes and lung parenchyma | Interstitium | Prominent mediastinal and hilar lymphadenopathy with associated pulmonary infiltrates; distribution may vary. |
| Sarcoidosis | Granulomatous disease with noncaseating granulomas; often presents with enlarged hilar/mediastinal nodes and interstitial lung involvement. | Lung interstitium and alveolar septa; mediastinal/hilar lymph nodes | Interstitium | Bilateral hilar and mediastinal lymphadenopathy with a perilymphatic distribution of micronodules, typically with an upper lobe predominance. |
| Primary Effusion Lymphoma (PEL) | HHV-8–driven lymphoma presenting as a lymphocytic-exudative pleural effusion without an associated parenchymal mass, typically in immunocompromised patients. | Pleural space | Pleura | Unilateral or bilateral pleural effusions without a discernible parenchymal mass; sometimes with mild pleural thickenin |