Congenital cyst adenomatoid malformations: resect some and observe all?

Sublobar Pulmonary Resection in Children With Congenital Lung Abnormalities: A Systematic Review

BACKGROUND

Lobectomy is currently the advised resection for symptomatic congenital lung abnormalities (CLA). Sublobar surgery is suggested as an alternative that enables to conserve healthy lung parenchyma. This systematic review aims to explore the outcomes of sublobar surgery in CLA patients as well as the corresponding surgical terminology and techniques.

METHODS

A systematic literature search was performed in adherence to PRISMA-P guidelines. The target population consists of children undergoing sublobar pulmonary resection for CLA. All studies were independently assessed by two reviewers, and evaluated by a third reviewer in case of disagreement.

RESULTS

The literature search yielded 901 studies of which 18 studies were included, comprising 1167 cases. The median chest tube insertion duration was 3.6 days (range 2.0-6.9 days), the median hospital admission was 4.9 days (range 2.0-14.5 days), and residual disease was diagnosed in 2% - leading to re-operation in 70%. The median incidence of postoperative complications was 15% (range 0-67%). Follow-up imaging was standard-of-care in 2/3 of studies. Due to the absence of standardised terminology, operative details and specification of resection type did not typically relate between studies.

CONCLUSIONS

Sublobar resection of CLA lesions could be a viable alternative to lobectomy in certain cases, with the advantage of conserving healthy lung parenchyma. Peri- and postoperative complications are comparable with those reported for conventional lobectomy. The incidence of residual disease following sublobar surgery appears to be lower than commonly stated. To improve comparability between studies, we recommend reporting perioperative characteristics in a structured format.

LEVEL OF EVIDENCE

Level IV.

Type III congenital pulmonary airway malformation associated with oesophageal atresia and tracheoesophageal fistula. A case report and review of literature

Congenital pulmonary airway malformation (CPAM) together with oesophageal atresia and tracheoesophageal fistula (TOF) is a very rare condition in neonates. We presented a case of an infant with Gross type C oesophageal atresia with TOF coexisting with Stocker Type III CPAM in our centre. It is interesting to know that TOF associated with type III CPAM has never been reported in the literature. The child was delivered through caesarean section, and because of respiratory distress post-delivery, endotracheal intubation was carried out immediately. CPAM was diagnosed by a suspicious finding from the initial chest X-ray and the diagnosis was confirmed through computed tomography scan of the chest. The patient was initially stabilised in a neonatal intensive care unit (NICU), and after the successful ligation of fistula and surgical repair of TOF, lung recruitment was started by high flow oscillatory ventilation. The patient recovered well without complications and able to maintain good saturation without oxygen support through the stay in the neonatal unit. Early recognition of this rare association is essential for immediate transfer to NICU, the intervention of any early life-threatening complications, and for vigilant monitoring in the postoperative period.

Accuracy of Chest Computed Tomography in Distinguishing Cystic Pleuropulmonary Blastoma From Benign Congenital Lung Malformations in Children

Importance

The ability of computed tomography (CT) to distinguish between benign congenital lung malformations and malignant cystic pleuropulmonary blastomas (PPBs) is unclear.

Objective

To assess whether chest CT can detect malignant tumors among postnatally detected lung lesions in children.

Design, Setting, and Participants

This retrospective multicenter case-control study used a consortium database of 521 pathologically confirmed primary lung lesions from January 1, 2009, through December 31, 2015, to assess diagnostic accuracy. Preoperative CT scans of children with cystic PPB (cases) were selected and age-matched with CT scans from patients with postnatally detected congenital lung malformations (controls). Statistical analysis was performed from January 18 to September 6, 2020. Preoperative CT scans were interpreted independently by 9 experienced pediatric radiologists in a blinded fashion and analyzed from January 24, 2019, to September 6, 2020.

Main Outcomes and Measures

Accuracy, sensitivity, and specificity of CT in correctly identifying children with malignant tumors.

Results

Among 477 CT scans identified (282 boys [59%]; median age at CT, 3.6 months [IQR, 1.2-7.2 months]; median age at resection, 6.9 months [IQR, 4.2-12.8 months]), 40 cases were extensively reviewed; 9 cases (23%) had pathologically confirmed cystic PPB. The median age at CT was 7.3 months (IQR, 2.9-22.4 months), and median age at resection was 8.7 months (IQR, 5.0-24.4 months). The sensitivity of CT for detecting PPB was 58%, and the specificity was 83%. High suspicion for malignancy correlated with PPB pathology (odds ratio, 13.5; 95% CI, 2.7-67.3; P = .002). There was poor interrater reliability (κ = 0.36 [range, 0.06-0.64]; P < .001) and no significant difference in specific imaging characteristics between PPB and benign cystic lesions. The overall accuracy rate for distinguishing benign vs malignant lesions was 81%.

Conclusions and Relevance

This study suggests that chest CT, the current criterion standard imaging modality to assess the lung parenchyma, may not accurately and reliably distinguish PPB from benign congenital lung malformations in children. In any cystic lung lesion without a prenatal diagnosis, operative management to confirm pathologic diagnosis is warranted.

Pleuropulmonary Blastoma in Pediatric Lung Lesions

BACKGROUND

Pediatric lung lesions are a group of mostly benign pulmonary anomalies with a broad spectrum of clinical disease and histopathology. Our objective was to evaluate the characteristics of children undergoing resection of a primary lung lesion and to identify preoperative risk factors for malignancy.

METHODS

A retrospective cohort study was conducted by using an operative database of 521 primary lung lesions managed at 11 children's hospitals in the United States. Multivariable logistic regression was used to examine the relationship between preoperative characteristics and risk of malignancy, including pleuropulmonary blastoma (PPB).

RESULTS

None of the 344 prenatally diagnosed lesions had malignant pathology (P < .0001). Among 177 children without a history of prenatal detection, 15 (8.7%) were classified as having a malignant tumor (type 1 PPB, n = 11; other PPB, n = 3; adenocarcinoma, n = 1) at a median age of 20.7 months (interquartile range, 7.9-58.1). Malignancy was associated with the DICER1 mutation in 8 (57%) PPB cases. No malignant lesion had a systemic feeding vessel (P = .0427). The sensitivity of preoperative chest computed tomography (CT) for detecting malignant pathology was 33.3% (95% confidence interval [CI]: 15.2-58.3). Multivariable logistic regression revealed that increased suspicion of malignancy by CT and bilateral disease were significant predictors of malignant pathology (odds ratios of 42.15 [95% CI, 7.43-340.3; P < .0001] and 42.03 [95% CI, 3.51-995.6; P = .0041], respectively).

CONCLUSIONS

In pediatric lung masses initially diagnosed after birth, the risk of PPB approached 10%. These results strongly caution against routine nonoperative management in this patient population. DICER1 testing may be helpful given the poor sensitivity of CT for identifying malignant pathology.

An adult patient with congenital pulmonary airway malformation and an esophageal cyst

Combined occurrence of both congenital pulmonary airway malformation (CPAM) and esophageal cyst is rare and its diagnosis requires a carefully pathologic examination. Differential diagnoses include malignant neoplasms of pulmonary origin, pulmonary inflammatory pseudotumor, bronchogenic cysts and other congenital lesions of esophagus and lung. This paper presented a rare case report of a 31-year-old adult male with combined type III CPAM and an esophageal cyst. The patient was misdiagnosed and treated for pneumonia and tuberculosis before being admitted to our hospital. To eliminate symptoms and make an accurate diagnosis, the patient received a right upper lobectomy and a complete excision of the cyst lesion via thoracotomy. The patient remained uneventful during 1-year follow-up observation.

Exercise capacity is not decreased in children who have undergone lung resection early in life for congenital thoracic malformations compared to healthy age-matched children

PURPOSE

The purpose of this study was to compare (i) the exercise capacity and (ii) lung function prior to and immediately post cardiopulmonary exercise tests (CPET) of children who underwent early life lung resection for Congenital Pulmonary Airway Malformations (CPAM) to healthy control children.

METHOD

Eight children with CPAM (four males, age 9.6 ± 1.8 years) and eight control children without respiratory disease (three males, age 9.4 ± 1.4 years) performed a CPET on a cycle ergometer, during which maximal oxygen consumption (V̇O_2max ) and heart rate were measured. Prior to and immediately post CPET, lung function measures including Nitrogen Multiple Breath Washout (MBW) and spirometry were performed.

RESULTS

There were no significant between group differences in pre CPET lung function (P > 0.05) or maximal exercise capacity (V̇O_2max CPAM: 39.4 mL^. kg^-1. min^-1 , Control: 40.5 mL^. kg^-1. min^-1 ). Post CPET, FEV₁ was significantly lower in the CPAM group, with two participants diagnosed subsequently with exercise induced bronchospasm based on post-CPET spirometry and follow-up clinical investigations.

CONCLUSION

Early life lung resection for CPAM does not appear to have negative implications for exercise capacity later in childhood. Clinicians should be aware that dyspnoea following exercise may be due to asthma rather than residual effects of CPAM in these children.

Thoracoscopic Vs open resection of congenital cystic lung disease- utilization and outcomes in 1120 children in the United States

PURPOSE

To determine if utilization of thoracoscopic resection of congenital cystic lung disease (CLD) is increasing and if this approach is associated with improved outcomes using a large national sample.

METHODS

Children ≤20years old who underwent resection of a congenital cystic adenomatoid malformation, bronchopulmonary sequestration, or bronchogenic cyst were identified from the Healthcare Cost and Utilization Project Kids' Inpatient Database (2009, 2012) and Nationwide Inpatient Sample (2008, 2010-2011). Patient characteristics and outcomes were compared between thoracoscopic and open approaches using univariate and multivariable analyses stratified by magnitude of resection.

RESULTS

Thoracoscopic resection was used in 39.4% of 1120 children who underwent resection of CLD. Utilization of the thoracoscopic approach increased from 32.2% in 2008 to 48.2% in 2012. Use of thoracoscopy was lower in lobectomy than segmental resection (32.5 vs 48.4%, p<.001). Newborns, those with comorbid congenital conditions, and those with respiratory infections also had lower rates of thoracoscopy. After stratifying by magnitude of resection and adjusting for patient complexity, complication rates and postoperative length of stay were similar between thoracoscopic and open approaches.

CONCLUSION

Utilization of thoracoscopic resection for CLD in the United States is increasing with time. After adjusting for patient complexity, there is no difference in postoperative length of stay or complications between thoracoscopic and open lobectomy and sub-lobar resection.

Morbidity after elective resection of prenatally diagnosed asymptomatic congenital pulmonary airway malformations

BACKGROUND/AIM

The optimal management of prenatally diagnosed asymptomatic congenital pulmonary airway malformations (CPAM) is controversial. Since there is a paucity of data relating to surgical risks in this specific population, we reviewed our experience to further inform this controversy.

METHODS

Ethically approved 10 year (2004-2013) retrospective review. Patients were included only if the CPAM was diagnosed prenatally and remained asymptomatic. Indication for surgery was physician recommendation and/or parental choice.

MAIN RESULTS

Sixty patients were identified. Median age at surgery was 6.5 months (range 65 days to 9.6 years). Resections were performed thoracoscopically (n = 51, one conversion) or by thoracotomy (n = 9). Surgical time was 2.5 hr (43 min to 4.75 hr). A chest drain was used in 58/60 and remained in situ 53 hr (23-108). There were no intra-operative complications or blood transfusions. All patients were extubated at the end of the procedure with no re-intubations. Post-operative hospitalization was 73.4 hr (23.8 hr to 4.2 days). Overall, complications occurred in 14/60 (23%). Eleven were minor but three were major: tension pneumothorax associated with new presentation of a small previously undiagnosed diaphragmatic hernia 5 days following resection; aggressive fibromatosis of the chest wall in the region close to resection 2 years later; and near-fatal hypovolemic cardiac arrest due to massive haemorrhage from a feeding vessel on postoperative day 7. There were no deaths and no cases of pleuropulmonary blastoma.

CONCLUSION

Resection of prenatally diagnosed asymptomatic CPAM is associated with a significant risk of complications, which may be life threatening. These data contribute to a balanced discussion of risks and benefits for these children.

Surgical versus conservative management of congenital pulmonary airway malformation in children: A systematic review and meta-analysis

BACKGROUND

The ideal management of infants born with asymptomatic congenital pulmonary airway malformation (CPAM) is controversial. We performed a systematic review and meta-analysis comparing elective resection versus expectant management.

METHODS

We searched CENTRAL, MEDLINE, EMBASE, CINAHL, and PubMed for studies describing the management of asymptomatic CPAM and reporting on postoperative morbidity, mortality, and length of hospital stay (LOS). We performed meta-analyses when possible and provide a narrative summary of results.

RESULTS

One nonrandomized prospective and eight retrospective studies met our inclusion criteria. Out of 168 patients, 70 underwent surgery before symptoms developed with seven experiencing postoperative complications (10.0%); 63 developed symptoms while being managed expectantly and subsequently underwent surgery with 20 complications (31.8%). Thirty-five patients continued to be followed nonsurgically (three months to nine years of follow-up). Morbidity was higher with surgery after symptom development (6 studies; odds ratio 4.59, 95% confidence interval (CI) 1.40 to 15.11, P<0.01); there was no difference in LOS (3 studies; mean difference 4.96, 95% CI -1.75 to 11.67, P=0.15). There were no related deaths.

CONCLUSIONS

Elective resection of asymptomatic CPAM lesions is safe and prevents the risk of symptom development, which may result in a more complicated surgery and recovery.

Can congenital pulmonary airway malformation be distinguished from Type I pleuropulmonary blastoma based on clinical and radiological features?

BACKGROUND

The management of congenital cystic lung lesions is controversial. Arguments for routine resection during infancy include the possibility of the lesion being Type I pleuropulmonary blastoma (PPB) rather than a cystic congenital pulmonary airway malformation (CPAM). We aimed to identify clinical and radiological features that might distinguish between CPAM and PPB and to develop a diagnostic algorithm based on these features.

METHODS

All recorded cases of Type I PPB were retrieved from the International PPB Registry and compared with an institutional cohort of children undergoing resection of CPAM (2002-2013) that was noted at some stage to be at least partially cystic. Regression models were created to identify variables that might differentiate CPAM from PPB. Odds ratio (OR) and positive predictive value (PPV) were calculated for each variable and a decision algorithm developed.

RESULTS

In 112 cases of Type I PPB and 103 of CPAM, factors favoring a diagnosis of CPAM included prenatal detection (OR 89.4), systemic feeding vessel (OR 61.7), asymptomatic (OR 8.0), and hyperinflated lung (OR 6.6). Factors favoring a diagnosis of PPB included bilateral or multisegment involvement (OR 2.4). A decision algorithm that helps to identify lesions requiring resection and those which can be safely observed is presented.

CONCLUSION

Clinical and radiological features can help to differentiate between CPAM and PPB. Our algorithm allows identification of children at higher risk of PPB in whom we would recommend resection and those at low risk in whom continued close observation is safe.

Should asymptomatic congenital cystic adenomatous malformations be removed? the case against

In this article, we debate the pros and cons for the surgical removal of asymptomatic antenatally diagnosed cystic adenomatous malformations (CCAM). It is often argued that asymptomatic antenatally diagnosed CCAMs should be surgically removed in infancy due to the risk of future malignancy, future risk of infection and other symptoms and of increased risk of surgery after infective episodes. However, the risk of malignancy is often overplayed and the risk may not even be decreased after excision of the CCAM. Furthermore, the risk of future symptoms is uncertain thus surgical removal will subject many infants to unnecessary risk. Medical follow up will decrease the numbers that undergo surgical intervention and newer imaging techniques are likely to decrease the radiation risk. Whichever route of management is followed there is an urgent need to outline the natural history of asymptomatic CCAMs.

Comparison between US and MRI in the prenatal assessment of lung malformations

BACKGROUND

The contribution of MRI in the prenatal evaluation of congenital lung abnormalities (CLA) has not been extensively investigated.

OBJECTIVE

(1) To compare diagnostic accuracy and assessment of prognostic factors between US and MRI in CLA and (2) to assess the diagnosis agreement between prenatal imaging and postnatal diagnosis.

MATERIALS AND METHODS

We included 23 consecutive fetuses who underwent concomitant US and MRI during gestation as well as postnatal CT and surgery (n = 22).

RESULTS

US-MRI sets were performed at median gestational age of 26 (n = 16) and 34 (n = 22) weeks. Postnatal diagnoses were 11 congenital pulmonary airway malformations (CPAM), 4 bronchopulmonary sequestrations (BPS), 6 hybrid lesions and 2 cysts. US and MRI agreement was significantly better during the second trimester than during the third one (P = 0.02). Disagreements were related to missed cysts (n = 5), mediastinal shift (n = 6) and vessels (n = 5). US and MRI diagnosis agreement was present in 20 cases, including 5 cases of misdiagnosis. US and MRI were concordant with postnatal diagnosis in 17 and 16 cases, respectively.

CONCLUSION

In our series, no clear superiority of MRI over US in the prenatal evaluation of CLA was demonstrated, but US better demonstrated systemic feeding vessels and MRI cysts and normal lung adjacent to the lesion.

[Congenital lung malformations: natural history and pathophysiological mechanisms]

INTRODUCTION

Congenital lung lesions comprise a broad spectrum of various malformations including congenital cystic adenomatoid malformation (CCAM), bronchopulmonary sequestration (BPS), congenital lobar emphysema, bronchial atresia and bronchogenic cyst. This review aims at the description of their natural history, and of the underlying pathophysiological mechanisms.

STATE OF THE ART

Congenital lung lesions are frequently diagnosed antenatally and many remain asymptomatic after birth. In the absence of antenatal identification, they are usually revealed by the occurrence of infection. In some cases, spontaneous resolution of the malformation can occur. Different pathogenic hypotheses are discussed for the origin of these abnormalities, and common processes appear likely to all of these malformations. Factors involved in the process of branching seem to play a particularly important role.

PERSPECTIVES

Prospective follow-up of operated and unoperated children would complete our knowledge about the natural history of these lesions. The contribution of experimental models has led to advances in the understanding of pathogenic mechanisms. Further studies are needed to identify the factors initiating the malformative process.

[When congenital lung malformations have to be operated?]

Both technical and anatomical features and the need for a long follow-up, usually over several years, explain the specificity of lung surgery in children. Apart from the oncological resections, the main indications for this surgery are congenital lung anomalies (cystic adenomatoid malformation, bronchopulmonary sequestration, lobar emphysema), symptomatic postinfectious lesions (bronchiectasis, atelectasis, abscess) and pneumothorax. Advances in miniaturization of the surgical equipment are used to carry the majority of these interventions by thoracoscopy, except when performed at the neonatal period. In the newborn, for which the indications for lung surgical resections are exceptional, ventilatory conditions and the tightness of the chest lead to still prefer open surgery. Pulmonary malformations can also be managed prenatally when they affect lung development or cause heart failure because of compressive complications. These interventions, performed after the 30th week of gestation, are not intended to remove the lesions, but to release the compression. But these procedures are still under evaluation and, in light of possible fetal and maternal complications, they should only be performed in tertiary centers and in the context of specific protocols.

[Congenital lung malformations--when to operate?]

Advances in antenatal imaging over the past 10 years have completely changed diagnosis and management of congenital lung disease, especially for congenital cystic adenomatoid malformations and sequestrations that are the two lesions most commonly detected. If early surgical excision is required for symptomatic cases, management of asymptomatic malformations is still discussed. The natural evolution and consequences of later complications of congenital lung malformations need to be compared with the benefits of elective resection and surgical morbidity. Complete regression of sequestrations or clinical and morphological improvement in congenital lobar emphysema pleads for clinical watching. On the other hand, resection is advocated for cystic malformations, because of an increased risk of acute respiratory distress, later infections and the possibility of malignant transformation. Even though the proportion of asymptomatic patients that go on to develop symptoms is hard to evaluate, an argument for elective surgery is a better outcome than emergency surgery. Further studies and long term follow-up are still needed to understand the natural history of congenital lung malformations precisely and help to define the optimal way in which to manage them.

MUC5AC, cytokeratin 20 and HER2 expression and K-RAS mutations within mucinogenic growth in congenital pulmonary airway malformations

AIMS

  To analyse the expression of several mucins (MUC1, MUC2, MUC3, MUC5AC and MUC6), epidermal growth factor receptor (EGFR), v-erb-b2 erythroblastic leukaemia viral oncogene homologue 2 (HER2), thyroid transcription factor-1 (TTF-1), caudal type homeobox 2 (CDX2) and cytokeratin 20 (CK20), and the presence of mutations of EGFR, KRAS and HER2 in congenital pulmonary airway malformations (CPAM).

METHODS AND RESULTS

  Forty-one cases of CPAM and six pulmonary sequestrations were included. TTF-1 expression was observed in all cases but was not seen in mucinogenic growths in CPAM. CDX2 expression was completely negative. MUC1 expression was noted in 12 (29%) CPAM and in 33% sequestrations. MUC5AC was noted in only five cases (26%) by immunohistochemistry and was found in the mucinogenic proliferations of type 1 CPAM. No immunolabelling was noted for the other mucins. EGFR was expressed variably in almost all cases, while HER2 and CK20 was seen exclusively in the mucinogenic proliferations. All mucinous growths were characterized by KRAS mutations. No EGFR and HER2 gene alterations were identified.

CONCLUSIONS

  KRAS mutations and MUC5AC, CK20 and HER2 expression was seen in all mucinogenic proliferations, supporting the neoplastic nature of these cytologically bland growths. These findings emphasize the importance of complete surgical resection of such lesions.

Malformações pulmonares congênitas

As malformações congênitas do pulmão são raras e variam muito na sua forma de apresentação clínica e gravidade, dependendo principalmente do grau de envolvimento pulmonar e de sua localização na cavidade torácica. Elas podem se manifestar em qualquer idade e podem ser fonte de importante morbidade e mortalidade em lactentes e crianças. Os indivíduos com malformações congênitas do pulmão podem apresentar sintomas respiratórios ao nascimento, enquanto outros podem permanecer assintomáticos por longos períodos. Atualmente, com o uso rotineiro da ultrassonografia pré-natal, vem ocorrendo um aumento no diagnóstico mais precoce dessas malformações. A manifestação clínica dessas malformações varia desde uma disfunção respiratória pós-natal imediata a um achado acidental na radiografia de tórax. O diagnóstico precoce e o tratamento imediato oferecem a possibilidade de um desenvolvimento pulmonar absolutamente normal. Quando assintomáticos, a conduta para o tratamento dos pacientes com malformações pulmonares ainda é controversa, uma vez que o prognóstico dessas afecções é imprevisível. O manejo dessas lesões depende do tipo de malformação e de sintomas. Devido ao risco de complicação, a maioria dos autores sugere a ressecção da lesão no momento em que essa é identificada. A lobectomia é o procedimento de escolha, fornecendo excelentes resultados a longo prazo. Este artigo descreve as principais malformações pulmonares congênitas, seu diagnóstico e controvérsias quanto o tratamento.

Death from bilateral pulmonary congenital cystic adenomatoid malformation: a rare case report

Congenital cystic adenomatoid malformation is one of rare pulmonary hypoplastic diseases. It has been subdivided into 3 types (I-III). Respiratory distress and hydrops are usually diagnosed pre- or postnatally by ultrasonography or radiography. The pathogenesis of CCAM has not been clarified yet. Here, we present an unusual case of bilateral CCAM (type III) of a 2-month-old infant who died suddenly. Concomitant lung malformation and fatty degeneration in hepatic cells make this case unique since such malformation is seldom found in type III CCAM.

A REVIEW OF POSTNATAL MANAGEMENT OF CONGENITAL PULMONARY AIRWAY MALFORMATIONS

Congenital cystic adenomatoid malformations of the lung (CCAMs) were originally described by Ch'In and Tang in 1949 as rare lung lesions occurring in premature or stillborn infants with anasarca. In 1977 Stocker et al divided CCAM into three types based on their clinical and pathological features. The nomenclature has since changed to congenital pulmonary airway malformations (CPAMs) to reflect the possible absence of cystic changes and the probable underlying pathogenesis of different types. CPAMs are relatively rare congenital abnormalities with a reported incidence varying from 1 in 10,000 to 1 in 35,000. There is a slight male predominance, but no racial predilection has been noted. This review will outline the current nomenclature and features of different types of CPAMs, highlight possible mechanisms underlying the development of CPAMs, review current antenatal imaging modalities and interventions, address the debate surrounding the postnatal management of CPAMs, and suggest areas for future research.

Pulmonary cysts in early childhood and the risk of malignancy

Surgery for congenital and early childhood lung cysts is often dictated by symptoms such as respiratory distress, infection or pneumothorax. Asymptomatic cysts present a therapeutic dilemma: surgical intervention and "conservative" observation have advocates. The risk of malignancy in such cysts is considered by some an indication for surgical intervention and is reviewed in this paper. Pleuropulmonary blastoma (PPB) is the most frequent malignancy associated with childhood lung cysts. Although rare, PPB occurs predictably in certain clinical and familial situations. This unique biology of PPB can inform the cyst management decision. The earliest manifestation of PPB is a malignant lung cyst in young children, clinically and radiographically indistinguishable from benign congenital lung cysts. Histopathologic examination differentiates cystic PPB from the benign cystic variants. Surgical excision of cystic PPB (with or without chemotherapy) cures approximately 85-90% of children. If not excised, cystic PPB evolves to cystic/solid or solid high-grade sarcoma (cure rate 45-60%) by age 2-6 years. Numerous reports of "malignancy in a congenital lung cyst" are now understood as the characteristic progression of cystic PPB. PPB is genetically determined in many cases. Detailed family history may reveal the hallmarks of PPB in the patient or young relatives: a unique constellation of diseases including lung cysts, cystic nephroma, childhood cancers, stromal sex-chord ovarian tumors, seminomas or dysgerminomas, intestinal polyps, thyroid hyperplasias, and hamartomas. Pneumothorax and multifocal/bilateral lung cysts also characterize PPB. These diagnoses predict that a lung cyst is more likely PPB than a benign congenital cyst. Patients fitting this pattern deserve histologic diagnosis. The genetic basis for this heritable syndrome is unknown but is being actively investigated.