42 Cystic Fibrosis

Clinical Presentation

An 18-month-old girl presents with recurrent episodes of respiratory distress and suspected pneumonia.

Figure 42A

Radiologic Findings

Frontal (Fig. 42A1) and lateral (Fig. 42A2) views of the chest in an 18-month-old girl reveal subtle early changes of lower airways disease, including mild diffuse overinflation and mild bilateral central bronchial wall thickening, consistent with early changes of cystic fibrosis. This was the third episode of suspected lower airway respiratory disease in the first year of life, prompting the child’s physician to perform a sweat test. Note that the area of subsegmental atelectasis is greater in the right upper lobe than in the left upper lobe.

Diagnosis

Early cystic fibrosis

Differential Diagnosis

Asthma
Unlucky child with recurrent episodes of bronchiolitis
Early immune deficiency, especially immunoglobulin deficiency
Recurrent aspiration
Primary ciliary dyskinesia

Discussion

Background

Cystic fibrosis is said to be the most common life-shortening inherited disease in the Caucasian population, affecting approximately 1 in 2500 live births in the United States and northern Europe. It is estimated that ~4% of whites are heterozygous for the most common form of the disorder.

Etiology

Current genetic technology has identified the genetic defect to be a mutation on the long arm of chromosome 7. The most common mutation is at the position dF 508 (70–80% of cases). The resultant mutation causes a physiologic disturbance in the sodium chloride ion transport system in epithelial cell membranes. This results in viscous secretions causing inspissated mucus in the tracheobronchial tree, digestive system, reproductive system, and sweat glands.