ALLERGIC AND IMMUNOLOGIC CONDITIONS

Allergic Rhinitis

Classification: Type I, IgE-mediated hypersensitivity of the nasal mucosa (Kishiyama et al., 2019).

Key diagnostic discriminator: Exposure-linked sneezing, itching, watery rhinorrhea, and pale boggy turbinates. Specific IgE supports sensitization only when it matches the clinical history (Kishiyama et al., 2019).

Clinical priority: Severe or untreated disease can contribute to sinusitis, auditory-tube dysfunction, reduced smell, sleep disturbance, asthma exacerbation, and chronic mouth breathing (Kishiyama et al., 2019).

Etiology and risk factors

  • Aeroallergens include seasonal pollens and perennial dust-mite, mold, cockroach, animal-dander, and occupational protein allergens (Kishiyama et al., 2019).
  • Atopy, asthma, atopic dermatitis, family history, and reproducible seasonal, household, or occupational exposure patterns increase probability (Kishiyama et al., 2019).

Pathophysiology

  • Initial sensitization drives a T-helper 2 response. Interleukin-4 and interleukin-13 promote B-cell class switching to allergen-specific IgE (Kishiyama et al., 2019).
  • Re-exposure cross-links IgE on mast cells and basophils. Histamine and other mediators produce the immediate phase: itching, sneezing, secretion, vasodilation, and edema (Kishiyama et al., 2019).
  • Hours later, eosinophils and other inflammatory cells sustain mucosal edema, congestion, hyperresponsiveness, and epithelial injury (Kishiyama et al., 2019).

Clinical manifestations

  • Paroxysmal sneezing, nasal or ocular itching, watery rhinorrhea, nasal obstruction, and watery eyes follow exposure to a relevant allergen (Kishiyama et al., 2019).
  • Nasal mucosa may appear pale blue and boggy. Repeated rubbing can produce an allergic salute and horizontal nasal crease, while persistent obstruction can cause chronic mouth breathing (Kishiyama et al., 2019).
  • Symptoms may be seasonal or perennial. Severe or untreated disease can contribute to sinusitis, auditory-tube dysfunction, reduced smell, sleep disturbance, and asthma exacerbation (Kishiyama et al., 2019).

Findings that argue against or redirect

  • Symptoms attributable to sinusitis or otitis media indicate a complication rather than uncomplicated nasal allergy (Kishiyama et al., 2019).
  • Frequent use of a topical nasal decongestant can produce rebound vasodilation and rhinitis medicamentosa (Kishiyama et al., 2019).
  • A compatible history and examination generally establish the clinical diagnosis. Use skin testing or serum allergen-specific IgE when the diagnosis is uncertain, symptoms do not respond to empiric treatment, or identifying the causative allergen would guide management (American Academy of Otolaryngology–Head and Neck Surgery Foundation, 2015; Kishiyama et al., 2019).

Diagnostic evaluation

  • Establish the temporal relationship between symptoms and seasonal, household, animal, or occupational exposures. Assess associated asthma and complications of chronic nasal obstruction (Kishiyama et al., 2019).
  • Confirm relevant sensitization with skin testing or serum allergen-specific IgE when testing is needed. Results must be interpreted with the clinical exposure history (Kishiyama et al., 2019).

Expected diagnostic and laboratory findings

  • A compatible exposure-linked history plus a positive skin test or serum allergen-specific IgE supports the diagnosis (Kishiyama et al., 2019).
  • Nasal mucosa may appear pale blue and boggy. Eosinophils may be present in nasal secretions, reflecting late-phase allergic inflammation (Kishiyama et al., 2019).
  • A horizontal nasal crease from repeated rubbing, chronic mouth breathing, and other findings of persistent obstruction may be present (Kishiyama et al., 2019).

Differential diagnosis

  • Rhinitis medicamentosa: persistent congestion associated with frequent topical decongestant use (Kishiyama et al., 2019).
  • Irritant-related nasal hyperresponsiveness: symptoms follow tobacco smoke, noxious odors, or other irritants rather than a relevant allergen-specific IgE pattern (Kishiyama et al., 2019).
  • Infectious complications of chronic rhinitis: sinusitis or otitis media is suggested by the corresponding focal symptoms and examination findings (Kishiyama et al., 2019).

Treatment and management

  • Reduce exposure to clinically relevant allergens. Intranasal corticosteroids are the most effective treatment for persistent nasal inflammation (Kishiyama et al., 2019; Norris, 2020).
  • Oral or intranasal antihistamines reduce itching, sneezing, and rhinorrhea. Topical nasal decongestants should be limited because repeated use can cause rebound congestion (Kishiyama et al., 2019; Norris, 2020).
  • Consider allergen immunotherapy when relevant sensitization is established and symptoms remain important despite exposure reduction and medication (Kishiyama et al., 2019; Norris, 2020).

Additional complications and red flags

  • Persistent symptoms should prompt assessment for asthma and the infectious or obstructive complications of chronic rhinitis (Kishiyama et al., 2019).

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References

American Academy of Otolaryngology–Head and Neck Surgery Foundation. (2015). Clinical practice guideline: Allergic rhinitis. https://www.entnet.org/quality-practice/quality-products/clinical-practice-guidelines/allergic-rhinitis/

Kishiyama, J. L., Chang, J. J., & Donovan, S. M. (2019). Disorders of the immune system. In G. D. Hammer & S. J. McPhee (Eds.), Pathophysiology of disease: An introduction to clinical medicine (8th ed.). McGraw-Hill Education.

Norris, T. L. (2020). Porth’s essentials of pathophysiology (5th ed.). Wolters Kluwer.