INTRODUCTION
Asthma is a heterogeneous disease that affects both children and adults,
with children prevalence that ranges from 4% to 30% in Latin America1. Despite little information on the impact of asthma
in developing countries, approximately 130,000 asthma-related
hospitalizations and a rate of 5 deaths/day were estimated in Brazil in
20131.
The clinical presentation is characterized by common symptoms such as
cough and wheezing, and physiologically with varying degrees of airflow
limitation. Typically, these changes occur in association with airway
inflammation and remodeling. In children, the mechanisms involved in
wheezing are distinct, and some phenotypes may be established from age
at onset, presence of atopy, and triggered by viral infections.
Approximately one-third of wheezing children will remain symptomatic in
adulthood, and factors such as allergic sensitization and smoking
increase the chance of its persistence2.
In recent decades, precision medicine has been used to better
characterize asthma phenotypes, thus establishing treatment alternatives
for patients with severe refractory asthma, which is the real challenge
for pulmonologists. Clustering is based on clinical characteristics
associated with complementary research, resulting in phenotypes such as
early onset allergic asthma or late onset asthma3.
However, within a given phenotype, distinct pathophysiological
mechanisms may be involved, even in a group of patients with similar
clinical presentation. This last concept brings what is now understood
as endotype, meaning knowledge at a more specific cellular and
immunological level3.
Sputum cytological analysis is cited as a safe and promising technique
that evaluates the cellularity present in the lower airway mucosa and
can be classified into four main cellular patterns: eosinophilic,
neutrophilic, mixed, and pauci-granulocytic. However, there is some
heterogeneity of these patterns among patients and their correlation
with clinical progression and inhaled corticosteroid treatment response
is still a challenge4.
Thus, the objective of this study was to evaluate the feasibility of
sputum cytology in children with asthma by recognizing inflammatory
patterns. The secondary objectives were to correlate cytological
patterns with clinical, epidemiological, and functional disease
variables.