Case 1: Chronic cough in a Vietnamese adolescent: Should we be sweating?

A 14-year-old Vietnamese boy presented with chronic cough and fever. Since childhood, he had been diagnosed and managed as a difficult asthmatic case despite multiple episodes of pneumonia. On examination, he was tachypneic, hypoxic and clubbed. Auscultation revealed bilateral crackles. A chest radiograph demonstrated significant bronchiectasis (Figure 1). A sputum culture grew Pseudomonas aeruginosa. His lung function was abnormal, with a forced vital capacity of 79% and a forced expiratory volume in 1 s of 72% of predicted. Extensive, diffuse bronchiectasis and bronchial wall thickening are noted throughout both lungs The patient was investigated for bronchiectasis; this ultimately revealed his true diagnosis. Four months later, he returned febrile with colicky abdominal pain and, again, proved to be a diagnostic dilemma. He was found to have intestinal obstruction, which was relieved with a barium contrast enema. Despite the boy's ethnic background, sweat tests were ordered and were surprisingly elevated (107 mmol/L and 110 mmol/L). Genetic analysis identified no testable cystic fibrosis (CF) mutations. Therefore, CF was diagnosed based on positive sweat chloride tests. Initially, the patient was found to be pancreatic sufficient (fecal elastase 457 μg/g). A misdiagnosis of asthma is not uncommon in patients with CF. CF should be suspected when there is protracted cough despite adequate therapy, recurrent respiratory infections or concomitant gastrointestinal symptoms. The delay in diagnosis of the present patient may have been partly due to the rarity of CF in the Vietnamese population. Only three cases have been reported in the CF Mutation Database of The Hospital for Sick Children (Toronto, Ontario). Without appropriate therapy, CF patients experience failure to thrive, nutritional deficits and progression of their lung disease. The present patient's mean delay in diagnosis was greater than 10 years, resulting in bronchiectasis and colonization of Pseudomonas. Pseudomonas growth is associated with a more rapid decline in lung function and poorer survival. On his second hospitalization, investigations were conducted to elucidate the etiology of his abdominal pain. An ultrasound showed a distended appendix greater than 6 mm in diameter. An abdominal computed tomography scan was suggestive of distal intestinal obstruction syndrome (DIOS) despite previous evidence of pancreatic sufficiency (PS). Subsequent investigations demonstrated pancreatic insufficiency. DIOS is caused by inspissated intestinal contents blocking the intestinal lumen. A total of 80% to 90% of patients with DIOS are pancreatic insufficient. However, other factors aside from the consequences of pancreatic insufficiency contribute to the development of DIOS and, thus, can occur in PS patients. The present patient initially had PS; then, his pancreatic function rapidly declined, resulting in DIOS. Abdominal pain in CF patients is difficult to evaluate because many CF-related comorbidities, such as gastroesophageal reflux, constipation or DIOS, present similarly. The present patient's clinical picture was complicated by right-lower quadrant abdominal pain and an enlarged appendix on ultrasound. It has been demonstrated that CF patients can routinely have misleadingly distended appendixes due to mucoid impaction. In contrast, diagnosis of appendicitis in CF patients may be delayed, resulting in perforation and abscess formation because of an initial mistaken diagnosis of DIOS. In conclusion, CF is the most common genetic condition affecting Caucasians. In other ethnic groups, it may be overlooked, with patients being diagnosed late despite having chronic respiratory symptoms. Delayed recognition is associated with increased mortality and morbidity. The present case describes the unusual presentation of CF in a Vietnamese teenager who presented with Pseudomonas colonization and lung damage. Not all cases of chronic cough are due to asthma. Poor response to treatment and recurrent infections should prompt additional investigations. CF should be considered in patients of any ethnicity. Sputum culture that isolates Pseudomonas is highly suggestive of bronchiectasis and demands that CF be excluded. DIOS should always be considered in CF patients despite evidence of PS.

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