Joseph Junewick, MD FACR
over 4 years ago
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Joseph Junewick, MD FACR
|Diagnostic Category: Infectious-Inflammatory
|Created: over 6 years ago
|Updated: over 6 years ago
9 year old female with cough and history of “recurrent pneumonias”.
Laboratory – positive p-ANCA
Pathology – Wedge biopsy revealed alveolar proteinosis
CR – Geographic central parahilar opacities.
CT – Sharply marginated geographic zones of alveolar opacitfication and scattered linear septal thickening with relative peripheral sparing.
Pulmonary alveolar proteinosis is a rare disease characterized by abnormal intraalveolar accumulation of surfactant-like material. Three distinct subgroups of alveolar proteinosis are currently recognized: idiopathic, secondary, and congenital. Idiopathic accounts for approximately 90% of cases. This form occurs worldwide, with an incidence of 0.36 new cases per 1 million persons each year. Secondary alveolar proteinosis occurs in patients with industrial inhalational exposure (e.g., silica particles, cement dust, aluminum dust, titanium dioxide, nitrogen dioxide, and fiberglass), underlying hematologic malignancy, or immunodeficiency disorders (immunosuppressive therapy and human immunodeficiency virus infection). Congenital alveolar proteinosis is quite rare and manifests in the neonatal period with severe hypoxia.
The common pathophysiology of these forms of alveolar proteinosis appears to be related to pulmonary surfactant and lung immune function, specifically deficiency of surfactant proteins or impaired function of granulocyte-macrophage colony-stimulating factor which is an essential regulator of immune defense and surfactant homeostasis.
Chest radiography typically reveals bilateral central and symmetric lung opacities, with relative sparing of the apices and costophrenic angles. The CT appearance is characterized as “crazy-paving” with smoothly thickened septal lines superimposed on areas of ground-glass opacity. Areas of crazy-paving are typically widespread and bilateral, often with sharply marginated areas of geographic or lobular sparing. Although the CT finding of crazy-paving is highly characteristic of alveolar proteinosis, it is also seen in infection, hemorrhage, neoplasia, inhalational disease, and hydrostatic pulmonary edema.
Frazier AA, et al. Pulmonary Alveolar Proteinosis. Radiographics 2008; 28:883-899.
Eric Payne, MD