Lymphocytic Interstitial Pneumonia (LIP)

Epidemiology

  • Sex: more common in females than males
  • Age: usually presents in 30’s-50’s (may be seen in children, particularly those with hypogammaglobulin-emia or AIDS)

Etiology

  • Dysproteinemia
    • Hypogammaglobulinemia
    • Monoclonal or Polyclonal Gammopathy
  • Autoimmune
    • Sjogrens Syndrome (see [[Sjogrens Syndrome]])
    • Chronic Active Hepatitis
    • Myasthenia Gravis (see [[Myasthenia Gravis]])
    • [[Primary Biliary Cirrhosis]]
    • Hashimotos Thyroiditis (see [[Hashimotos Thyroiditis]])
    • Pernicious Anemia (see [[Pernicious Anemia]])
    • Autoimmune Hemolytic Anemia (see [[Hemolytic Anemia]])
    • Rheumatoid Arthritis (see [[Rheumatoid Arthritis]])
    • SLE (see [[SLE]])
  • Allogeneic Bone Marrow/Stem Cell Transplant (see [[Bone Marrow Transplant]])
  • Infection
    • HIV Disease (see [[HIV Disease]])
    • Epstein-Barr Virus (see [[Epstein-Barr Virus]])
    • HTLV-1
    • Tuberculosis (see [[Tuberculosis]])
    • Following Legionellosis (see [[Legionellosis]])
  • Celiac Sprue
  • Drugs
    • Captopril (see [[Captopril]])
    • Flecainide (see [[Flecainide]])
    • Phenytoin (see [[Phenytoin]])
  • Surfactant Protein C Deficiency
  • Idiopathic Lymphocytic Interstitial Pneumonia

Physiology

  • Lymphocytic infiltration of interstitium of lung
  • Must be differentiated from pseudolymphoma/ primary pulmonary lymphoma/ lymphomatoid granulomatosis/ benign lymphocytic angiitis and granulomatosis/ plasma cell interstitial pneumonia

Pathology

  • Monotonous sheets of lymphocytes infiltrating interstitium and alveolar spaces
  • May also have interstitial macrophages, non-caseating granulomas, perivascular amyloid deposits, and germinal lymphoid centers

Diagnosis

  • CXR: reticuar -> mixed alveolar+interstial pattern -> cysts/honeycombing
  • HRCT: ground glass

ABG: hypoxemia
PFT’s: restrictive pattern with decreased DLCO
FOB: BAL lymphocytosis (>35%) may be seen (also seen in Sarcoid, Berylliosis, HP, drug-induced ILD, lymphoma)
-Increased plasma cells and macrophages
OLB: required for diagnosis in almost all cases

CXR/Chest CT patterns:
1) ILD: reticulonodular pattern (most common)
2) Mixed alveolar-interstitial infiltrates: due to coalescence
3) Hilar/ mediastinal nodes: in some cases
4) Honeycombing: small cysts (seen best in lower fields) seen late/ radiographic honeycombing correlates well with pathologic honeycombing
5) Pleural effusion: uncommon (suggests presence of complicating lymphoma)

Hypo or hypergammaglobulinemia: may be seen

Serum autoantibodies or immune complexes: may be positive


Clinical

  • Clubbing (common)
  • Dyspnea:
  • Cough:
  • Pleuritic Chest Pain:
  • Bibasilar Rales:
  • Pulmonary HTN: late

Other System Involvement:
a) Lymphadenopathy:
b) Keratoconjunctivitis sicca:
c) Salivary Gland Enlargement:
d) Hepatosplenomegaly:
e) Fever:
f) Weight Loss:
g) Clubbing:
h) Cyanosis:

Complications:
1) Transformation into Low-Grade Pulmonary or Systemic Lymphoma: may occur in some cases
2) Infection (especially in cases with associated dysproteinemia):


Treatment

  • Steroids: may markedly improve disease (cited in few case reports)
    • Some cases progress to death despite therapy

Prognosis

  • Determined mainly by course of underlying disease

References

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