Mold Allergy Differential Diagnoses

Updated: Dec 02, 2020
  • Author: Shih-Wen Huang, MD; Chief Editor: Harumi Jyonouchi, MD  more...
  • Print

Diagnostic Considerations

Allergic rhinitis and allergic conjunctivitis

Consider the following:

  • Viral infectious rhinitis

  • Nasal congestion as a complication of pregnancy

  • Oral contraceptives

  • Rhinitis medicamentosa (rebound vasodilation due to drugs such as Neo-Synephrine, terbutaline, and reserpine)

  • Tumors

In children, the presence of congenital choanal atresia or a foreign body should be considered. The presence of nasal polyps should be carefully excluded.

Differential diagnoses for allergic conjunctivitis include but are not limited to infectious conjunctivitis (viral and bacterial) and vernal conjunctivitis.

Allergic asthma

For patients with wheezing, after a carefully obtained history, the following conditions must be excluded:

  • Medical conditions involving the lung that manifest with symptoms suggestive of asthma

  • Syndromes characterized by abnormal breathing in which the lungs are structurally normal

  • Cases of local airway obstruction that manifest with wheezing that is audible to the patient or can be heard on examination

For those with cough without wheezing, the following conditions must be excluded:

  • Cardiac failure with acute pulmonary edema

  • Cardiac failure secondary to myocardial infarction

  • Pulmonary embolism

  • Tracheobronchitis

For children with wheezing or cough, asthma needs to be differentiated from the following conditions:

  • Infections - Bronchiolitis, pneumonia, croup, tuberculosis, bronchitis

  • Anatomic or congenital conditions - Cystic fibrosis (CF), vascular ring, dysmotile cilia syndrome, immune deficiency, congestive heart failure, laryngotracheomalacia, tracheoesophageal fistula, gastroesophageal reflux

  • Hypersensitivity vasculitis - Allergic bronchopulmonary aspergillosis (ABPA), hypersensitive pneumonia, periarteritis nodosa

  • Other - Foreign-body aspiration, pulmonary thromboembolism, psychogenic cough, sarcoidosis, bronchopulmonary dysplasia

Allergic fungal sinusitis (AFS)

Differential diagnoses include conditions that lead to chronic sinus diseases, including the following:

  • Immune deficiency

  • Ciliary dyskinesia

  • Aspirin hypersensitivity with nasal polyp

  • Anatomic defect with small ostium of sinus

  • Poorly treated sinusitis

Poor response to prolonged antibiotic treatment should raise the suspicion for allergic fungal sinusitis (AFS), and a workup for the disease should be initiated.

Allergic bronchopulmonary aspergillosis and allergic bronchopulmonary mycosis

The following conditions and findings must be excluded for diagnosis:

  • Asthma not associated with mold allergy

  • Chest radiographic infiltrate (eg, atelectasis, mucoid impactions, middle-lobe syndrome)

  • Bronchiectasis caused by other diseases

  • Other forms of hypersensitivity pneumonitis

Extrinsic allergic alveolitis (EAA)

Individuals who are exposed to mycotoxin in an atmosphere with molds may develop symptoms of respiratory illness now defined as organic dust toxic syndrome. The disease is due to toxicity, not hypersensitivity. Another condition that must be excluded is nitrogen oxide pneumonitis, which is reported in individuals working in silos.

Other diseases that should be excluded include the following:

  • Cryptogenic fibrosing alveolitis

  • Pneumoconiosis

  • Tuberculosis

  • Metastatic cancer of the lung

Any infection, inflammation, or drug reaction leading to a fibrotic process of the lung also should be considered as differential diagnosis.

Worth re-emphasis is that mold-exposed patients can present with various immunoglobulin E (IgE)-mediated and non-IgE-mediated symptoms. Mycotoxins, irritation by spores, or metabolites may be culprits in non-IgE–mediated presentations; environmental assays have not been perfected. Symptoms attributable to the toxic effects of molds and not attributable to IgE or other immune mechanisms need further evaluation regarding their pathogenesis. However, immune, rather than toxic, responses seemed to be the major causes of symptoms in most studies.

Differential Diagnoses