Lymphocytic interstitial pneumonitis
Lymphocytic interstitial pneumonitis (LIP) is a benign lymphoproliferative disorder characterised by lymphocyte predominant infiltration of the lungs. It is classified as a subtype of interstitial lung disease. It also falls under the umbrella of non-lymphomatous pulmonary lymphoid disorders.
LIP can occur at any age. However, most of the patients are adults with a mean age of 50 years. If a child presents with LIP, can be indicative of AIDS.
There is a recognised female predilection most likely attributable to the fact that LIP occurs in patients with autoimmune disease such as Sjogren syndrome, which is by far more common in women 8.
The main clinical symptoms are a gradual onset of dyspnea and cough with approximately six months duration. Less frequently, patients may have systemic symptoms such as fever, night sweat, arthralgia, and weight loss. If the disease progresses to the end-stage respiratory failure cyanosis and clubbing may develop. Hypertrophy of the salivary glands observed in 20% of patients 11.
There is diffuse infiltration of the interstitium and alveolar spaces by lymphocytes and plasma cells.
- Sjogren syndrome: can occur in up to 25% of those with LIP 6
- AIDS: particularly if it occurs in the young 9
- autoimmune thyroid disease
- systemic lupus erythematosus (SLE)
- Castleman disease
- common variable immune deficiency (CVID)10
- rheumatoid arthritis
In about 80% of patients polyclonal or IgM monoclonal gammopathy is found 8.
Features can be non-specific, but may include:
The following features may be seen with LIP on HRCT, but the findings are not exclusive to its diagnosis:
- features tend to be diffuse with mid to lower lobe predominance
- thickening of bronchovascular bundles
- interstitial thickening along lymph channels 2
- small but variable sized pulmonary nodules (can be centrilobular or subpleural, and often ill-defined)
- ground-glass change
- scattered thin walled cysts
- usually deep within the lung parenchyma
- typically abuts vessels (i.e. is perivascular or subpleural)
- size range from 1-30 mm (useful for differentiation between lymphoma of the lung 1)
- mediastinal lymphadenopathy
Treatment and prognosis
The natural history is variable, from near complete resolution to progressive disease. More than 30% of patients will develop the end-stage disease and honeycombing despite treatment.
Transformation to lymphoma can occur particularly in a patient with monoclonal gammopathy or hypogammaglobulinemia 8. Corticosteroids have been successfully trialled 1.
General imaging differential considerations include:
pneumocystis pneumonia (PCP)
- can be difficult to differentiate particularly in those with AIDS
- occur in younger females
- cysts are generally uniformly distributed throughout the lungs
Langerhans cell histiocytosis (LCH)
- bizarre cysts that spare the costophrenic angles
- upper lung zone predominant
Interstitial lung disease
interstitial lung disease
- drug-induced interstitial lung disease
- hypersensitivity pneumonitis
idiopathic interstitial pneumonia (mnemonic)
- acute interstitial pneumonia (AIP)
- cryptogenic organising pneumonia (COP)
- desquamative interstitial pneumonia (DIP)
- idiopathic nonspecific interstitial pneumonia (NSIP)
- idiopathic pleuroparenchymal fibroelastosis
- lymphoid interstitial pneumonia (LIP)
- respiratory bronchiolitis–associated interstitial lung disease (RB-ILD)
- usual interstitial pneumonia / idiopathic pulmonary fibrosis (UIP/IPF)
- 1.Honda O, Johkoh T, Ichikado K et-al. Differential diagnosis of lymphocytic interstitial pneumonia and malignant lymphoma on high-resolution CT. AJR Am J Roentgenol. 1999;173 (1): 71-4. AJR Am J Roentgenol (abstract) - Pubmed citation
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- 7. Glickstein M, Kornstein MJ, Pietra GG et-al. Nonlymphomatous lymphoid disorders of the lung. AJR Am J Roentgenol. 1986;147 (2): 227-37. AJR Am J Roentgenol (abstract) - Pubmed citation
- 8. Ferguson EC, Berkowitz EA. Lung CT: Part 2, The interstitial pneumonias-clinical, histologic, and CT manifestations. AJR Am J Roentgenol. 2012;199 (4): W464-76. doi:10.2214/AJR.10.7309 - Pubmed citation
- 9. Das S, Miller RF. Lymphocytic interstitial pneumonitis in HIV infected adults. Sex Transm Infect. 2003;79 (2): 88-93. Free text at pubmed - Pubmed citation
- 10. Cha SI, Fessler MB, Cool CD et-al. Lymphoid interstitial pneumonia: clinical features, associations and prognosis. Eur. Respir. J. 2006;28 (2): 364-9. doi:10.1183/09031936.06.00076705 - Pubmed citation
- 11. Dähnert W. Radiology Review Manual. Lippincott Williams & Wilkins. (2011) ISBN:1609139437. Read it at Google Books - Find it at Amazon