1.3 Allergy and recurrent acute rhinosinusitis (RARS) in
children.
We found very limited and heterogeneous data linking allergy to RARS and
it was not possible to perform a qualitative analysis.
Choi
et al.(34) evaluated the predisposing factors that may
be associated with chronic and recurrent RS examining 296 patients with
RS younger than 13 years of age. The prevalence of allergic rhinitis,
atopy, and asthma were significantly higher in patients with chronic and
recurrent RS than those with acute and subacute RS. Veskitkul et
al.(35) evaluated the clinical characteristics and
predisposing factors of RARS in children as well as the preventive
therapy. The authors suggested that allergic rhinitis may be considered
a predisposing factor because it was detected in 35.1% of cases,
concluding that children with RARS should be always evaluated for the
presence of underlying predisposing conditions including allergic
disease. Nevertheless, no comparison with a control group was performed
and for this reason data are not definitely supporting a link between
allergy and RARS.
Allergy and Chronic Rhinosinusitis (CRS) in Children.
Chronic rhinosinusitis (with or without nasal polyps) in children is
defined as: presence of two or more symptoms, one of which should be
either nasal blockage/obstruction/congestion or nasal discharge
(anterior/posterior nasal drip) with or without facial pain/pressure
and/or cough for ≥12 weeks associated to pathognomonic endoscopic signs
or CT changes(7). The prevalence of CRS in children is
lower than in adults (2-4%), nevertheless, the negative impact on
quality of life seems to be similar to that observed in adults. Studies
on CRS in children are less common and it is more difficult to
investigate the relationship with allergy(7). Several
factors contribute to complicate the analyses including incomplete
evaluation (nasal endoscopy and/or imaging are rarely performed in many
children) and the difficulty to differentiate CRS from adenoid
hypertrophy, adenoiditis, and (allergic) rhinitis. In fact, nasal
blockage may occur in AR children, due to edematous mucosa, neurogenic
and vascular responses, over-production of secretions, and impaired
muco-ciliary clearance leading to congestion of the ostia and symptoms
simulating rhinosinusitis. On the other hand, the blockage leads to
stagnant debris and acidotic environment that might stimulate bacteria
overgrowth(36, 37).
Histopathological analysis(38,39) demonstrated that
pediatric CRS is quite different from the adult form, showing greater
inflammatory cellularity, higher density of submucosal lymphocytes, less
eosinophilic inflammation, basement membrane thickening, and mucous
gland hyperplasia, suggesting a different pathway compared to the adult
CRS pattern, which is predominantly characterized by a Th2-oriented
response with polypoid changes. The presence of nasal polyps in a
pediatric patient should suggest the hypothesis of cystic fibrosis that
has not been included in this paper. More specifically, some evidence
supports the hypothesis that CRS in children over the age of 13 seems to
be based more on eosinophilic inflammation, while under this age CRS
seems to be based more on neutrophilic inflammation, thus justifying the
lower prevalence of nasal polyps in children than in
adult(38, 39).
Several manuscripts support the hypothesis that AR and CRS could be
different faces of the same disease. AR, in fact, is typically
characterized by a Th2 immune response involving IL-4, IL-5 and IL-13
which drives IgE production and recruitment of eosinophil granulocytes.
It has been suggested(40-44) that eosinophils, by
generating potent toxic agents (cationic proteins, oxygen-free radicals,
and proinflammatory cytokines), may play a major role in initiating and
perpetuating inflammation of sino-nasal mucosa in patients with AR.