Clinical Background
Hypersensitivity pneumonitis has several synonyms, including hypersensitivity syndrome and extrinsic allergic alveolitis.
Etiologies
- Thermophilic actinomyces - farmer lung, bagassosis
- Fungi/mold - maple bark disease, malt-worker lung
- Animal proteins - pituitary snuff-taker lung, pigeon breeder disease
- Chemicals - bathtub finisher lung
Pathophysiology
- Type III immune complex disease
- Also includes type IV cell-mediated immunity
- Inhaled antigen acts upon alveolar macrophages to activate them and causes the release of enzymes which results in inflammation and fibrosis
Clinical Presentation
- Chills, fever
- Dyspnea, cough, airway obstruction
- Weight loss
- Disease process may be progressive with eventual fibrotic lung disease
Treatment
- Removal from antigen exposure
- May require corticosteroid therapy
See Also
Diagnosis
Diagnosis
- Early identification of hypersensitivity is crucial for removal of offending antigens and initiation of treatment
- Suspect in patients with recurring pneumonias or pneumonitis
- Laboratory testing
- Serum precipitating antibodies
- Imaging studies
- Chest X-ray - ground glass appearance suggesting pneumonia
Tests generally appear in the order most useful for common clinical situations
| Test name: Hypersensitivity Pneumonitis I
|
| ARUP #: 0055076 |
| Methodology: Immunodiffusion
|
| Use: Diagnose presence of antibodies to Aspergillus fumigatus 1 & 6, Aureobasidium pullulans, Pigeon serum, Micropolyspora faeni and Thermoactinomyces vulgaris when supported by historical and clinical evidence |
| Limitations: Absence of positive test does not rule out hypersensitivity pneumonitis |
| Follow-up: Consider either transbronchial or thoracoscopic biopsy |
| Test name: Hypersensitivity Pneumonitis II
|
| ARUP #: 0055226 |
| Methodology: Immunodiffusion
|
| Use: Diagnose presence of antibodies to Aspergillus flavus, Aspergillus fumigatus 2 & 3, Saccharomonospora viridis, Thermoactinomyces candidus and Thermoactinomyces sacchari when supported by historical and clinical evidence |
| Limitations: Absence of positive test does not rule out hypersensitivity pneumonitis |
| Follow-up: Consider either transbronchial or thoracoscopic biopsy |
| Test name: Hypersensitivity Pneumonitis Extended Panel (Farmer's Lung Panel)
|
| ARUP #: 0050157 |
| Methodology: Immunodiffusion/ImmunoCAP®
|
| Use: Includes allergen and antibody testing from hypersensitivity pneumonitis I and II tests; additionally, allergen testing for fungi and molds, Phoma betae, food, beef, pork, epidermals & animal proteins and feathers |
| Limitations: Absence of positive test does not rule out hypersensitivity pneumonitis |
| Follow-up: Consider either transbronchial or thoracoscopic biopsy |
| Test name: Lymphocyte Subsets Panel 4 - T-Cell Subsets Percents & Ratio, Bronchoalveolar Lavage
|
| ARUP #: 0093420 |
| Methodology: Flow Cytometry
|
| Use: Determine activity of the disease |
References
General References
Bush RK, Portnoy JM, Saxon A, Terr AI, Wood RA. The medical effects of mold exposure. J Allergy Clin Immunol.
2006;
117(
2):
326-333.
Fink JN, Ortega HG, Reynolds HY, Cormier YF, Fan LL, Franks TJ, Kreiss K, Kunkel S, Lynch D, Quirce S, Rose C, Schleimer RP, Schuyler MR, Selman M, Trout D, Yoshizawa Y. Needs and opportunities for research in hypersensitivity pneumonitis. Am J Respir Crit Care Med.
2005;
171(
7):
792-798.
Jacobs RL, Andrews CP, Coalson JJ. Hypersensitivity pneumonitis: beyond classic occupational disease-changing concepts of diagnosis and management. Ann Allergy Asthma Immunol.
2005;
95(
2):
115-128.
Mohr LC. Hypersensitivity pneumonitis. Curr Opin Pulm Med.
2004;
10(
5):
401-411.
Slavin RG. What the allergist should know about hypersensitivity pneumonitis. Allergy Asthma Proc.
2007;
28(
1):
25-27.
Medical Reviewers
Hill, Harry R., M.D. Group Medical Director, Laboratory of Immunology, ARUP Laboratories, and Executive Director of the ARUP Institute for Clinical and Experimental Pathology; Professor and Division Head, Clinical Pathology, University of Utah
Litwin, Christine, M.D. Medical Director, Immunology at ARUP Laboratories; Professor, Clinical Pathology, University of Utah
Comprehensive Review: November 2007
Last Update: May 2008
