Pulmonary Interstitial Glycogenosis: A Reversible Underlying Condition Associated With D-Transposition of the Great Arteries and Severe Persistent Pulmonary Hypertension

Early onset children's interstitial lung diseases: Discrete entities or manifestations of pulmonary dysmaturity?

Interstitial lung diseases in children (chILD) are rare and diverse. The current classifications include a group of early onset chILD specific to infancy, namely neuro-endocrine cell hyperplasia of infancy (NEHI), pulmonary interstitial glycogenosis (PIG) and the alveolar capillary-congenital acinar dysplasia (ACD-CAD) spectrum, as well as alveolar growth disorders. NEHI and PIG cells are seen in the normal developing foetal lung. We hypothesise that these conditions are in fact overlapping manifestations of pulmonary dysmaturity, respectively of airway, mesenchymal and vascular elements, rather than discrete clinical conditions in their own right. Clinically, these present as respiratory distress in early life. Mild cases rightly never undergo lung biopsy, and for these the clinical description 'persistent tachypnoea of infancy' has been proposed. In terms of pathology, we reviewed current literature, which showed that NEHI cells decline with age, and are not specific to NEHI, which we confirmed by unpublished re-analysis of a second dataset. Furthermore, specific genetic disorders which affect pulmonary maturation lead to a histological picture indistinguishable from NEHI. PIG and ACD-CAD are also associated with pulmonary growth disorders, and manifestations of PIG and NEHI may be present in the same child. We conclude that, contrary to current classifications, NEHI, PIG, and ACD-CAD should be considered as overlapping manifestations of pulmonary dysmaturation, frequently associated with disorders of alveolar growth, rather than as separate conditions. Identification of one of these patterns should be the start, not the end of the diagnostic journey, and underlying in particular genetic causes should be sought.

Persistent Pulmonary Hypertension Without Underlying Cardiac Disease as a Presentation of Pulmonary Interstitial Glycogenosis

INTRODUCTION

Pulmonary interstitial glycogenosis (PIG) is an idiopathic lung condition that remains clinically underrecognized despite a growing body of literature.

CASE REPORT

We present a case of PIG with pulmonary hypertension without underlying cardiac disease. This patient presented with respiratory distress and spontaneous pneumothorax at 6 months of age. Laboratory and imaging investigations demonstrated nonspecific features, but refractory pulmonary hypertension was confirmed on cardiac catheterization. Lung tissue histopathology showed glycogen positive staining of the interstitial cells, consistent with PIG.

CONCLUSION

This unique case demonstrates that pulmonary hypertension can be seen in the setting of PIG without associated cardiac anomalies, and persists despite treatment in an otherwise self-limited condition.