Hypersensitivity pneumonitis

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Última revisión: 20 Aug 2025

Última actualización: 09 Sep 2025

Hypersensitivity pneumonitis (HP) is an inflammation of the alveoli and distal bronchioles caused by an immune response to inhaled allergens.

Exposure to an antigen is the key epidemiologic factor - most commonly including Actinomycetes bacteria, animal proteins, or reactive chemicals.

Diagnosis requires a high index of suspicion when evaluating individuals with interstitial lung disease or recurrent flu-like illness.

Various tests may be used to corroborate a presumptive diagnosis, but no test is pathognomonic.

Treatment involves avoidance of the causative agent and use of corticosteroids.

Definición

HP, also known as extrinsic allergic alveolitis, is the result of non-IgE mediated immunologic inflammation. HP is caused by repeated exposure to an antigen, usually through inhalation. Potential antigens include proteins of natural plant or animal origin, a chemical conjugated to a human airway protein (such as albumin), and some drugs (via ingestion).[1][2] The inflammation of HP manifests itself in the alveoli and distal bronchioles. Historically, HP has been categorized as acute, subacute, or chronic, depending on the frequency, duration, and intensity of exposure, and the duration of illness.[3][4] However, these categories are not easily separated. The American Thoracic Society, Japanese Respiratory Society, and Latin American Thoracic Association diagnostic guidelines published in 2020 classify patients as having fibrotic or nonfibrotic HP. Classification is determined by the predominant presence or absence of fibrosis on radiologic and/or histopathologic exam.[5] Many cases of HP are caused by occupational exposure.[6][7]

Anamnesis y examen

Principales factores de diagnóstico

exposure to avian protein antigen, especially excrement
mold in work environment
occupational exposure to chemicals
dyspnea
cough

Todos los datos

Otros factores de diagnóstico

fever/chills
malaise
weight loss/anorexia
bibasilar rales
diffuse rales
clubbing

Todos los datos

Factores de riesgo

smoking
viral infection
exposure to avian protein antigen
exposure to mold antigen
exposure to bacterial antigen
exposure to diisocyanate (e.g., epoxy resin)
exposure to acid anhydride antigen (e.g., paint refinisher)
exposure to metalworking fluid
use of certain drugs
use of e-cigarettes
ayurvedic medicine

Todos los datos

Pruebas diagnósticas

Primeras pruebas diagnósticas para solicitar

chest x-ray
high-resolution CT chest
serum antigen-specific IgG or IgA
pulmonary function tests
diffusing lung capacity of carbon monoxide

Todos los datos

Pruebas diagnósticas que deben considerarse

bronchoalveolar lavage
lung biopsy

Todos los datos

Algoritmo de tratamiento

Agudo

all patients

Colaboradores

Autores

Leslie Grammer, MD

Professor

Northwestern University Feinberg School of Medicine

Director

Ernest S. Bazley Asthma and Allergy Center

Clinic Practice Director

Allergy-Immunology

Northwestern Medical Faculty Foundation

Chicago

Divulgaciones

LG declares that she has no competing interests.

Revisores por pares

Maximiliano Tamae-Kakazu, MD, FCCP

Associate Professor of Medicine

Program Director, Pulmonary and Critical Care Medicine Fellowship

Research Director, Pulmonary and Critical Care Medicine

Corewell Health West - Michigan State University College of Human Medicine

East Lansing

Divulgaciones

MTK received fees from InflaRx as a consultant to participate in a COVID-19 pneumonia Advisory Board. MTK received fees from Pfizer as a consultant to participate in a healthcare disparities in primary immunodeficiencies advisory board. MTK received fees from Regeneron as consultant on the pathophysiology of asthma and need of education in fellowship programs advisory board in January 2022. All the honoraria have been donated to the Corewell Health Foundation.

Toby M. Maher, MB, MSc, PhD, MRCP

Consultant Respiratory Physician

Interstitial Lung Disease Unit

Royal Brompton Hospital

London

Divulgaciones

TMM has received consultancy fees from GSK, Actelion, and Philips Respironics. He has received lecture fees from Astra Zeneca and holds an unrestricted industry-academic grant from GSK.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

Referencias

Nuestros equipos internos de evidencia y editoriales colaboran con colaboradores expertos internacionales y revisores pares para garantizar que brindemos acceso a la información más clínicamente relevante posible.

Artículos principales

Raghu G, Remy-Jardin M, Ryerson CJ, et al. Diagnosis of hypersensitivity pneumonitis in adults. An Official ATS/JRS/ALAT clinical practice guideline. Am J Respir Crit Care Med. 2020 Aug 1;202(3):e36-69.Texto completo Resumen

Quirce S, Vandenplas O, Campo P, et al. Occupational hypersensitivity pneumonitis: an EAACI position paper. Allergy. 2016 Jun;71(6):765-79.Texto completo Resumen

Fernández Pérez ER, Travis WD, Lynch DA, et al. Diagnosis and evaluation of hypersensitivity pneumonitis: CHEST guideline and expert panel report. Chest. 2021 Aug;160(2):e97-156.Texto completo Resumen

Artículos de referencia

Una lista completa de las fuentes a las que se hace referencia en este tema está disponible para los usuarios con acceso a todo BMJ Best Practice.

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Hypersensitivity pneumonitis

Resumen

Definición

Anamnesis y examen

Principales factores de diagnóstico

Otros factores de diagnóstico

Factores de riesgo

Pruebas diagnósticas

Primeras pruebas diagnósticas para solicitar

Pruebas diagnósticas que deben considerarse

Algoritmo de tratamiento

all patients

Colaboradores

Autores

Leslie Grammer, MD

Divulgaciones

Revisores por pares

Maximiliano Tamae-Kakazu, MD, FCCP

Divulgaciones

Toby M. Maher, MB, MSc, PhD, MRCP

Divulgaciones

Peer reviewer acknowledgements

Disclosures

Referencias

Artículos principales

Artículos de referencia

Una lista completa de las fuentes a las que se hace referencia en este tema está disponible para los usuarios con acceso a todo BMJ Best Practice.

Diferenciales

Guías de práctica clínica

Videos

Inicie sesión o suscríbase para acceder a todo el BMJ Best Practice

Inicie sesión o suscríbase para acceder a todo el BMJ Best Practice

Inicie sesión para acceder a todo el BMJ Best Practice