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Pulmonary interstitial glycogenosis: a new variant of neonatal interstitial lung disease
Anne-Marie Canakis1, Ernest Cutz, David Manson
1Division of Respiratory Medicine, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
Insights
A new infant lung disease, pulmonary interstitial glycogenosis, is characterized by glycogen accumulation in lung cells. Early treatment shows promising outcomes for affected neonates.
Area of Science:
- Neonatal Medicine
- Pulmonology
- Pathology
Background:
- Atypical neonatal lung disease presents diagnostic challenges.
- Interstitial lung diseases in neonates require precise characterization.
Observation:
- Seven infants presented with tachypnea, hypoxemia, and diffuse interstitial infiltrates.
- Chest radiographs showed diffuse infiltrates and overinflated lungs.
- Lung biopsies revealed interstitial expansion by spindle-shaped cells with glycogen.
Findings:
- Cells were vimentin positive, negative for macrophage markers.
- Electron microscopy showed primitive mesenchymal cells with abundant glycogen.
- Alveolar lining cells had minimal or no glycogen.
Implications:
- Pulmonary interstitial glycogenosis is proposed as a new neonatal lung disease entity.
- Abnormal cytodifferentiation of interstitial mesenchymal cells is postulated.
- Early treatment with corticosteroids and hydroxychloroquine shows favorable outcomes.
Abstract:
We present the clinical, radiologic, and pathologic findings in lung biopsies from seven infants with atypical neonatal lung disease. All seven infants presented with tachypnea, hypoxemia, and diffuse interstitial infiltrates with overinflated lungs on chest radiographs in the first month of life. Lung biopsies from all cases showed similar pathology, with expansion of the interstitium by spindle-shaped cells containing periodic acid-Schiff positive diastase labile material consistent with glycogen. Immunohistochemical staining showed these cells to be vimentin positive but negative for leucocyte common antigen, lysozyme, and other macrophage markers. Electron microscopy revealed primitive interstitial mesenchymal cells with few cytoplasmic organelles and abundant monoparticulate glycogen. Minimal or no glycogen was seen in the alveolar lining cells. Five cases were treated with pulse corticosteroids; hydroxychloroquine was added in one case. Six of seven infants have shown a favorable clinical outcome. One infant died from complications of extreme prematurity and bronchopulmonary dysplasia. Three cases that have been followed for at least 6 years have shown clinical resolution and radiographic improvement. We propose the term "pulmonary interstitial glycogenosis" of the neonate for this new entity to be differentiated from other forms of interstitial lung disease. Because abundant glycogen is not normally found in pulmonary interstitial cells, we postulate an abnormality in lung cytodifferentiation involving interstitial mesenchymal cells.