Lymphocytic Interstitial Pneumonitis

Lymphocytic Interstitial Pneumonitis

Jud W. Gurney, MD, FACR

Coronal NECT shows multiple thin-walled cysts image in a background of diffuse ground-glass opacities. The diagnosis was lymphocytic interstitial pneumonitis.

Axial CECT shows peribronchovascular ground-glass opacities image in a patient with Sjögren syndrome and lymphocytic interstitial pneumonitis.


Abbreviations and Synonyms

  • Lymphocytic interstitial pneumonia (LIP), pseudolymphoma, lymphoid interstitial pneumonia, diffuse hyperplasia of bronchus-associated lymphoid tissue (BALT), mucosa-associated lymphoid tissue (MALT)


  • Part of spectrum of idiopathic interstitial pneumonias

    • Lymphoproliferative disorder ranging from follicular bronchiolitis to low-grade lymphoma

  • Diffuse disease commonly referred to as LIP

  • Focal disease commonly referred to as nodular lymphomatoid hyperplasia (pseudolymphoma)

  • Nonneoplastic lymphoproliferation must be differentiated from lymphoma by immunologic stains

    • Monoclonal cell lines in lymphoma, polyclonal in nonneoplastic lymphoproliferative disorders


General Features

  • Best diagnostic clue: Thin-walled cysts and centrilobular nodules

  • Patient position/location: Centered on lymphatic pathways: Peribronchovascular, centrilobular, septa, and pleura

CT Findings

  • Radiographic findings centered on lymphatic pathways in lung

    • Peribronchovascular, septa, pleura

  • Diffuse (LIP)

    • Ground-glass opacities (100%)

      • Distribution: Bilateral (90%), diffuse (60%), peripheral distribution (10%)

    • Centrilobular nodules

      • Poorly defined, 2-4 mm in size

    • Thin-walled cysts

      • Most distinctive finding (80%)

      • Range 1-30 mm in diameter (average 5 mm)

      • Involve < 10% of total lung

      • May be isolated finding

    • Combination of ground-glass opacities, centrilobular nodules, and thin-walled cysts common

    • Other findings (related to lymphatic pathways)

      • Subpleural nodules (> 50%)

      • Septal thickening (80%)

      • Thickening of small bronchovascular bundles (tree-in-bud pattern)

      • Bronchiectasis (20%)

      • Rarely fibrosis and honeycombing

  • Focal (pseudolymphoma)

    • Air-space mass, consolidation with air-bronchograms

    • Nodules (> 5 mm)

      • Peribronchial in distribution

      • Up to 30 mm in size (average 10 mm)

    • No lobar predilection

    • Cavitation rare

  • Evolution

    • All findings may resolve except for cysts

    • Centrilobular nodules may evolve into cysts

    • Airspace consolidation may evolve into honeycombing

  • Lymph nodes may be enlarged (up to 70%), usually multiple nodal groups

    • More common in AIDS patients

    • Not large enough to see on radiography

  • Pleural effusions rare

Radiographic Findings

  • Usually nonspecific findings, better evaluated with CT

    • Diffuse disease (LIP)

      • Diffuse interstitial thickening, predominately basilar

      • Multiple pulmonary nodular opacities often with air-bronchograms (more common in AIDS)

    • Focal

      • Focal central airspace mass(s), segmental or lobar in size mimicking pneumonia

      • Over time gradually grow toward periphery of lung

      • May also arise in lung periphery

      • Unilateral or bilateral

  • Pleural effusions rare

  • Associated findings

    • Anterior mediastinal mass: Thymoma

      • Predisposing condition for hypogammaglobulinemia or myasthenia gravis, either of which may lead to LIP

    • Splenomegaly


Nonspecific Interstitial Pneumonitis

  • Cellular or fibrotic, temporally homogeneous at histology

  • Idiopathic or seen with collagen vascular diseases

  • Ground-glass opacities in bronchovascular distribution

Angioimmunoblastic Lymphadenopathy

  • Lymphoproliferative disorder associated with dysproteinemia and immunodeficiency

  • Generalized lymphadenopathy and hepatosplenomegaly

  • Skin rash

  • Pleural effusion

  • Lung may be normal or have focal mass-like areas of consolidation

Castleman Disease

  • Benign lymphoproliferative hyperplasia of lymph nodes

  • Hilar or mediastinal adenopathy

    • Hyaline vascular form: Nodes have intense contrast enhancement

  • Lungs less likely to be abnormal (if abnormal may be due to co-existing LIP)

Lymphomatoid Granulomatosis

  • Multiple pulmonary nodules (may be cavitary)

  • Skin rash

  • Central nervous system (CNS) disease

Hypersensitivity Pneumonitis

  • Appropriate antigen exposure

  • Diffuse ground-glass opacities and centrilobular nodules

  • Lobular air-trapping more common

  • Cysts and adenopathy much less common

Thin-Walled Cysts

  • Laryngotracheal papillomatosis

  • Pneumatoceles

    • Trauma

    • Pneumocystis jiroveci pneumonia

    • Staphylococcus pneumonia

    • Hydrocarbon ingestion

  • Langerhans granulomatosis

  • Lymphangiomatosis

  • Centrilobular emphysema

  • Metastases

  • Birt-Hogg-Dubé syndrome: Multiple renal oncocytomas/cancer, skin lesions


General Features

Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Lymphocytic Interstitial Pneumonitis

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