Pediatric Hypersensitivity Pneumonitis Differential Diagnoses

Updated: May 20, 2016
  • Author: Harold J Farber, MD, MSPH; Chief Editor: Girish D Sharma, MD, FCCP, FAAP  more...
  • Print
DDx

Diagnostic Considerations

See the list below:

  • Acute hypersensitivity pneumonitis (HP) closely resembles viral or bacterial infections of the lower respiratory tract.

  • Bird exposure can place the patient at risk for psittacosis.

  • Granulomatous lung diseases (eg, tuberculosis, histoplasmosis, coccidiomycosis, sarcoidosis) can also produce findings similar to those of subacute hypersensitivity pneumonitis. [11]

  • Lymphoid interstitial pneumonitis observed in patients with acquired immunodeficiency syndrome (AIDS) can manifest as dyspnea, crackles, interstitial infiltrates, and hypergammaglobulinemia.

  • For patients residing or working in a farm setting, organic toxic dust syndrome can be provoked by bacterial endotoxins or fungal toxins. [71]

  • Zamboni disease (a toxic reaction to nitrogen oxides emitted from an ice-smoothing machine operated in an indoor ice rink) can mimic acute or subacute hypersensitivity pneumonitis. [72]

  • Differentiating chronic hypersensitivity pneumonitis from idiopathic pulmonary fibrosis is particularly important because the prognosis for the former improves when the offending antigen is identified and eliminated.

  • Subacute and chronic hypersensitivity pneumonitis has been misdiagnosed as asthma, a condition that can also cause cough, dyspnea, and exercise intolerance. [2]

  • Chronic hypersensitivity pneumonitis may be misdiagnosed as anorexia nervosa. Anorexia, weight loss, and exercise intolerance are manifestations of both diseases.

  • Connective-tissue disease (eg, systemic lupus erythematosus) can cause noninfectious pneumonitis with fever and weight loss, but other clinical and laboratory features of the connective tissue disease are expected.

  • Drug-induced pneumonitis is considered separately from pneumonitis triggered by inhaled antigens. Medications most often implicated in drug-induced pneumonitis include gold salts, methotrexate, and amiodarone. Rare causes of drug-induced pneumonitis are the nonsteroidal anti-inflammatory drugs aspirin and ibuprofen; the anticonvulsants carbamazepine and phenytoin; the antibiotics nitrofurantoin and dapsone; the sulfonamides sulfasalazine and sulfadoxine; the antimalarial chloroquine; the immunosuppressants penicillamine and cyclophosphamide; and the cytotoxic agents azathioprine, bleomycin, chlorambucil, cyclophosphamide, mitomycin, and vinblastine.

Differential Diagnoses