Hidden foreign body in an unexplained asthma

Foreign body aspiration (FBA) is a common condition with potential to cause significant morbidity and mortality. In children, highest incidence is within the first 3 years of life. Without witnessed aspiration or acute symptoms such as choking, coughing or respiratory distress, it may go unnoticed as clinical presentation and radiological investigations generally have low diagnostic value. Delay in diagnosis increases the risk of developing severe complications. Unexplained recurring or persistent lung pathologies in this age group should raise suspicion of FBA, and early bronchoscopy is warranted for confirmation of diagnosis. We report a case of FBA in a 2-year-old boy whom had been symptomatic for 3 months and was treated as bronchial asthma prior to diagnosis of foreign body in the left bronchus.


Introduction:
Foreign body aspiration is a common and potentially fatal accident.According to the National Safety Council, it is the fourth leading cause of death due to unintentional injury in the United States in 2004, and the mortality rate was estimated to be 1.5 per 100,000 population 1 .Classical history consists of choking episode followed by coughing, wheezing, stridor, or acute respiratory distress 2 .Especially in children, the acute event may go unnoticed, and foreign body aspiration may be mimicked as other illness such as bronchial asthma, bronchitis, or pneumonia.The delay of making an accurate diagnosis may lead to dangerous consequences for the patient 4 .

Case report:
A 2-year-old boy presented with history of persistent non-productive cough for 3 months, followed by fever in past 1 week associated with occasional noisy breathing.He was brought to emergency department due to progressive dyspnea.Prior to this, he has been seen by several primary care practitioners and the diagnosis of bronchial asthma has been made.However the treatment given failed to control his symptoms.There was no history of witnessed foreign body aspiration.He was otherwise well and active at home.Examination revealed a febrile boy but not in respiratory distress.He was not cyanosed and there was no stridor.Wheeze was heard on auscultation at the middle and lower zone of the left lung.
Breath sound was equal bilaterally.Baseline blood investigation was normal, including the white blood cell count.Chest X-ray showed a radiopaque spring-like foreign body situated in the left main bronchus.No other significant finding was noted in the x-ray.
Rigid bronchoscopy was done under general anesthesia, revealed a small metal spring in the left main bronchus.It was removed completely without difficulty by using the rigid optical forceps.The left main bronchus noted to be mildly inflamed without any laceration, slough or pus.No other foreign body was found.
He had an uneventful recovery, and was discharged home a day after the bronchoscopy.

Discussion:
In children, FBA most commonly occurs within the first 3 years of life 3,[5][6][7] .This can be attributed to several factors: tendencies of putting things in their mouth for exploration; incomplete molar reducing effective chewing; and incomplete swallowing reflex 3 .Male to female ratio is 2:1, reflecting the more adventurous games and impulsive nature of the boys 3,5,6 .Majority of the aspirated material is organic, seeds and nuts being the most common, comprising between 50 to 78% of all foreign body found in the reviewed studies 3,5 7 .Size, shape, and surface of the aspirated foreign body, and anatomical condition of the patient determine the lodgement location.Preferential of the foreign bodies to be located in right bronchus can be explained by the wider and more in-line right bronchus with the trachea as compared to the angulated left bronchus.
Positive history of aspiration noticed by a witness is the most important clue for FBA, which unfortunately is not always available 2 .Most common presentation of FBA is persistent cough [5][6][7] as in this case.Other sign and symptom includes dyspnea, wheezing, stridor, or cyanosis.Fever is suggestive of contaminated or chemically irritating foreign body, or patient has developed infective complications such as pneumonia or lung abscess 2 .Clinical triad of cough, localized  wheezing and localized decreased breath sound has been reported to be present in 15-40% of patients.About 5% of patients with positive FBA were asymptomatic on presentation 3,6 .
The value of chest X-ray (CXR) in diagnosing FBA remains controversial.Radiopaque foreign body is only present in 2-15% of cases, and CXR was reported as normal in 16-61%

Conclusion:
In summary, FBA is a common accident in children with potential to cause significant morbidity and mortality.High index of suspicion is needed in cases with atypical presentation or unexplained persistent bronchial asthma.

Figure 1 :
Figure 1: Erect PA chest x-ray showing radiopaque material in the region of left main bronchus.

Figure 2 :
Figure 2: A metal spring removed from the left main bronchus.
6he technique used depends on the type of foreign body and the ability of the individual operator6.