Pseudoazygos lobe caused by lymph node pneumatocele

Area of Science:

• Medical Imaging
• Infectious Diseases
• Pulmonology

Background:

• Patients with Acquired Immunodeficiency Syndrome (AIDS) have a high incidence of pulmonary tuberculosis, increasing their risk for severe esophageal tuberculosis.
• Tuberculous esophagitis and esophageal fistulae are known complications, but their frequency in AIDS patients may be underestimated.

Observation:

• A rare case of tuberculous mediastinal lymphadenopathy in an AIDS patient is presented.
• CT scans revealed a fistula between a large lymph node and the esophagus.
• The lymph node's necrotic content was entirely replaced by air, forming a 'lymph nodal pneumatocele', a previously undescribed entity.

Findings:

• Complete air filling of a large mediastinal lymph node (lymph nodal pneumatocele) secondary to tuberculous fistula in an AIDS patient.
• This pneumatocele mimicked an azygos fissure on frontal chest radiography, representing a novel cause of false azygos lobe appearance.

Implications:

• Highlights the importance of considering tuberculosis in AIDS patients presenting with esophageal fistulae.
• Emphasizes that large lymph nodes can completely "shell out" with air in this context.
• Warns against mistaking this appearance for a normal variant, crucial for accurate diagnosis and management.