Structure

• lower lobe predominance
• infiltration of lymphocytes and plasma cells into the
  • perilymphatic
    • bronchovascular bundles
    • venules
  • interstitium.

Rare

• Typical onset at ages 40 – 70 years old but can occur at any age (Chest 2002;122:2150)
• Typically in patients with Sjogren’s syndrome
• lower lobe predominance
• GGO’s
• Can have MALT lymphoma
• and Amyloidosis Light chain deposition disease
• More common in women
• No association with smoking history

• Bilateral lower lobes of the lung

Lower Lobes Why?

• exact reason for this preference is
• not completely understood,
  • One possible explanation
  • lower lobes of the lungs are
  • more dependent on gravity, which
  • may affect the distribution of
  • lymphocytes and
  • other immune cells that are involved in the development of LIP.
    • Gravity may cause these cells to accumulate more easily in the lower lobes, where
    • blood flow and ventilation are also generally
      • lower
      • compared to the upper lobes.
• lymphatic drainage of the lower lobes
• less than the upper lobes, which could lead to the
  • accumulation of lymphocytes in the lower lobes.
• certain infections or environmental exposures that may
• contribute to the development of LIP
• may also have a greater impact on the lower lobes of the lungs.

Disease Process

• infiltration of lymphocytes and plasma cells into the lung interstitium

• Pathogenic mechanisms of LIP are still unclear
• Has aspects of lymphoproliferative disease and lymphoid hyperplasia of polyclonal T or B cells (Chest 2002;122:2150)
• Although it may transform to lymphoma, especially MALT, the risk is lower than initially reported (Eur Respir J 2006;28:364)

• Associated with several systemic diseases and conditions
  • Autoimmune (most common)
    • Sjögren syndrome (SjS); 25% of LIP cases have SjS and 1% of SjS cases present with LIP
    • Rheumatoid arthritis
    • Systemic lupus erythematosus
    • Polymyositis / dermatomyositis
    • Hashimoto disease
    • Hypothyroidism
    • Castleman disease
    • Myasthenia gravis
    • Autoimmune hemolytic anemia
    • Pernicious anemia
    • Primary biliary cirrhosis
  • Infection
    • Human immunodeficiency virus (HIV)
    • Epstein-Barr virus
    • Human T cell lymphotropic virus type 1
    • Legionella pneumonia
    • Mycoplasma
    • Chlamydia
    • Tuberculosis
  • Immunodeficiency
    • Acquired immunodeficiency syndrome (AIDS); especially in children
    • Monoclonal or polyclonal gammopathy
    • Common variable immunodeficiency
  • Idiopathic LIP accounts for 20% of cases (Eur Respir J 2006;28:364)

• Very slowly progressive respiratory symptoms
  • Dyspnea on exertion
  • Dry cough
  • Systemic symptoms such as malaise, fever and weight loss
  • Duration of the symptoms prior to diagnosis can exceed a year
• Bibasilar inspiratory crackles on chest auscultation

• Based on clinical, radiological and pathological findings (multidisciplinary diagnosis)
• No firm diagnostic criteria currently exist

• Dysproteinemia is often present
  • Hypergammaglobulinemia is more common than hypogammaglobulinemia
• Restrictive pattern on pulmonary function tests
  • Reduced forced vital capacity (FVC)
  • Reduced diffusing capacity of the lung for carbon monoxide (DLCO)

• Chest radiography
  • Bibasilar opacities with lower lobe predominance
• High resolution computed tomography (Eur J Radiol 2015;84:542, Respirology 2016;21:600)
  • Ground glass opacity with / without consolidation with lower lobe predominance
  • Cyst formation and thickening of bronchovascular bundle and interlobular septa are often present
  • Cysts often remain even after resolution of symptoms