Solitary unilocular cyst of the lung with features of persistent interstitial pulmonary emphysema: report of four cases

Persistent Pulmonary Interstitial Emphysema With Respiratory Infection: A Clinicopathological Analysis of Six Cases and Detection of Infectious Pathogens by Metagenomic Next-Generation Sequencing (mNGS)

BACKGROUND

Persistent pulmonary interstitial emphysema (PPIE) is known to be related to mechanical ventilation and preterm. However, PPIE is also reported rarely in non-ventilated and full-term infants. Its relationship with respiratory infection is rarely reported in the literature. PPIE is difficult to diagnose and always mimics other congenital thoracic malformations (CTMs), such as congenital cystic adenomatoid malformation (CCAM).

OBJECTIVE

The objective of this study was to evaluate clinicopathological and radiographic features of PPIE with respiratory infection and to detect the possible infectious pathogens.

METHODS

From January 2011 to December 2019, six cases were confirmed pathologically with PPIE from a large cohort of 477 resected CTMs in West China Hospital of Sichuan University. Clinical and radiographic features were obtained from patients' medical records and follow-up. The present study aimed to analyze clinicopathological and radiographic features and to detect the infectious pathogens by metagenomic next-generation sequencing (mNGS).

RESULTS

The six PPIE cases included four girls and two boys, ranging from 2 months to 5 years; 100% (5/5) of the available cases were full-term and without mechanical ventilation. CCAM were suspected in 66.7% (4/6) patients; 66.7% (4/6) cases affected a single lobe, and 33.3% (2/6) cases affected both lung lobes. Clinically, all six PPIEs were presented with symptoms of respiratory infection and diagnosed with pneumonia. All six patients were treated by surgery after anti-infective treatment. The pathologic characteristics showed lung cysts with variable size along the bronchovascular bundles, the cysts had a discontinuous fibrotic wall with a smooth inner surface lined with uninucleated and/or multinucleated macrophages. Streptococcus pneumoniae was detected in patient No. 1. Human beta-herpesvirus 5 was detected in patient No. 2. Neisseria mucosa, Neisseria sicca, Prevotella melaninogenica, Prevotella histicola, and Fusobacterium nucleatum were detected in patient No. 5, and no infectious pathogen was detected in 50% (3/6, No. 3, No. 4, and No. 6) of cases.

CONCLUSION

Six rare cases of PPIE with respiratory infection were treated by surgery after anti-infective treatment. All five available cases were full-term infants without mechanical ventilation. The histological characteristics of PPIE were the wall of cysts composed of a thin layer of discontinuous fibrous tissue and lined with uninucleated or/and multinucleated macrophages.

Persistent pulmonary interstitial emphysema presenting as solitary lung cyst in a preterm infant

Solitary unilateral lung cyst is an unusual finding in preterm infants. It may be difficult to distinguish acquired from congenital lung cysts clinically. The definitive diagnosis is histological; however, CT scan of the chest is a useful diagnostic tool. We present an extremely preterm infant with solitary lung cyst and background chronic lung disease. The initial chest x-rays showed solitary right lung cyst. At 6 weeks he required an escalation of ventilator support coupled with x-ray evidence of increased size of the cyst. CT scan confirmed large solitary cyst of the right lower lobe with evidence of compression and mediastinal shift, suspicious of congenital cystic adenomatoid malformation. The cyst was surgically removed in view of clinical deterioration. However, histology showed persistent pulmonary interstitial emphysema (PPIE). This case illustrates that in the context of prematurity PPIE can present as a solitary lung cyst and may require surgery.

Emphysematous cystitis in a chemically-induced diabetic dog

Emphysematous cystitis is a rare disorder caused by bacterial infection and characterized by gas accumulation within the bladder wall with cyst formation. This report describes the histopathological characteristics of emphysematous cystitis found in a diabetic female beagle induced by streptozotocin and alloxan. Macroscopically, multiple cyst-like structures were observed on the cut surface of the urinary mucosa. During fixation, small specimens cut from the mucosa floated on the surface of the fixative solution. Histopathologically, multiple cysts were lined with a single layer of flattened cells found to be immunohistochemically positive for vimentin, partially positive for α-smooth muscle actin or macrophage scavenger receptor, class A, and thought to be myofibroblasts, fibroblasts or macrophages. Multinucleated giant cells were observed around the cysts, and gram-negative short bacilli were observed in the lumen of the urinary bladder. From these findings, this case was diagnosed as emphysematous cystitis.

Cystic lung disease in infants and children

Cysts within the lung are one of the more common pulmonary pathological findings seen in an active pediatric surgical pathology service. Of both developmental and acquired origin, they may present as respiratory distress in infants or may be asymptomatic lesions incidentally discovered by images studies of the thoracic for "non-pulmonary" reasons. The most frequently seen developmental cysts of the lung are those of Congenital Pulmonary Airway Malformations, types 1, 2 & 4. Other congenital cystic lesions include bronchogenic cysts (usually in older patients) and some of the enteric duplication lesions that contain cysts. Acquired cystic lung lesions include acute and persistent pulmonary interstitial emphysema, postinfarction peripheral cysts, postinfectious pulmonary cysts, and the cystic form of pleuropulmonary blastoma.

Spontaneous resolution of diffuse persistent pulmonary interstitial emphysema

Persistent pulmonary interstitial emphysema (PPIE) is a rare condition that occurs in both preterm and term infants. It is thought to arise from a disruption of the basement membrane of the alveolar wall allowing air entry into the interstitial space. The characteristic CT scan appearance of PPIE can be used to differentiate it from other congenital cystic lesions that may present similarly. Although conservative management is accepted as the initial form of management in most cases, a review of the published literature found that a significant proportion of localized PPIE cases eventually require surgical resection. This case illustrates that extensive bilateral PPIE associated with a persistent pneumomediastinum can resolve spontaneously thus demonstrating that conservative management without surgical intervention may be appropriate for some children.

Acquired Nonneoplastic Neonatal and Pediatric Diseases

The lung biopsy is an established procedure to procure a pathologic diagnosis in a child with a suspected pneumonic process of undetermined etiology. Improvements in pediatric anesthesia and surgery have reduced the operative complications to a minimum. A biopsy can usually be taken through a small intercostal incision when localization is not especially important in a patient with diffuse changes (see Chapter 1). The alternative method for tissue sampling is the endoscopic transbronchial biopsy. There is less risk to the patient, but the specimen is smaller and crush artifacts from the instrument are more common.

Spontaneous pulmonary interstitial emphysema in a term unventilated infant

Pulmonary interstitial emphysema (PIE) is a form of air block most frequently seen in ventilated preterm infants with severe lung disease; it is rarely reported in spontaneously breathing term infants. We report on an infant previously diagnosed with laryngomalacia and congestive heart failure and with evidence of antenatal stroke before the onset of pulmonary disease. He presented at 6 weeks of age with spontaneous pneumothorax. Focal cystic changes were seen on imaging studies of the lungs. There was no prior history of mechanical ventilation. Prior chest X-rays did not show cystic changes. He subsequently underwent resection of the affected lung areas. Pathologic examination revealed persistent PIE with cystic expansion, pleural blebs, and reactive pleuritis, as well as subpleural air-space enlargement. The patient did well postoperatively and was discharged home without further problems. This case demonstrates that PIE can occur in an infant without any history of mechanical ventilation, suggesting the need for a high index of suspicion for PIE, even in nonventilated and spontaneously breathing term neonates. PIE should be included in the differential diagnosis of cystic lung lesions in all young infants.

The use of pulmonary interstitial emphysema as an indicator of live birth

Making the determination of live birth versus stillbirth in a discarded newborn infant based on gross and microscopic autopsy findings can be a challenging task for the forensic pathologist. The traditional criteria for live birth determination are frequently challenged in court, and indisputable evidence of live birth remains elusive. The histologic finding of pulmonary interstitial emphysema has not been considered as a useful determinant of live birth. The authors report two cases of discarded newborn infants in which the finding of pulmonary interstitial emphysema was used as an indicator of live birth.

Persistent interstitial pulmonary emphysema-like cyst associated with metastatic synovial sarcoma

Interstitial pulmonary emphysema is characterized by the presence of gas dissecting the interstitial tissues of the lung. Clinically, it may be acute or persistent, and the latter can be further categorized as localized or diffuse. Usually, it appears in preterm neonates with a history of assisted ventilation or respiratory distress. Although far from frequent, the localized variety of persistent interstitial pulmonary emphysema (PIPE) can develop spontaneously in full-term babies or infants without any obvious underlying pulmonary disease. Histologically, PIPE is characterized by the presence of uni- and multinucleated histiocytes lining the inner surface of the cysts. In this report, we describe a 15-year-old male with synovial sarcoma (SS) of the right ankle diagnosed 4 years previously who developed pulmonary metastasis, one of which presented cystic changes with features of PIPE.