Imaging of pulmonary fibrosis in children: A review, with proposed diagnostic criteria.

Computed tomography (CT) imaging findings of pulmonary fibrosis are well established for adults and have been shown to correlate with prognosis and outcome. Recognition of fibrotic CT findings in children is more limited. With approved treatments for adult pulmonary fibrosis, it has become critical to define CT criteria for fibrosis in children, to identify patients in need of treatment and those eligible for clinical trials. Understanding how pediatric fibrosis compares with idiopathic pulmonary fibrosis and other causes of fibrosis in adults is increasingly important as these patients transition to adult care teams. Here, we review what is known regarding the features of pulmonary fibrosis in children compared with adults. Pulmonary fibrosis in children may be associated with genetic surfactant dysfunction disorders, autoimmune systemic disorders, and complications after radiation, chemotherapy, transplantation, and other exposures. Rather than a basal-predominant usual interstitial pneumonia pattern with honeycombing, pediatric fibrosis is primarily characterized by reticulation, traction bronchiectasis, architectural distortion, or cystic lucencies/abnormalities. Ground-glass opacities are more frequent in children with fibrotic interstitial lung disease than adults, and disease distribution appears more diffuse, without clearly defined axial or craniocaudal predominance. Following discussion and consensus amongst a panel of expert radiologists, pathologists and physicians, distinctive disease features were integrated to develop criteria for the first global Phase III trial in children with pulmonary fibrosis.

Computed tomographic findings in TBX4 mutation: a common cause of severe pulmonary artery hypertension in children.

BACKGROUND: Mutations in the T-Box 4 (TBX4) gene are a lesser-known cause of heritable pulmonary arterial hypertension (PAH). Patients with heritable PAH typically have worse outcomes when compared with patients with idiopathic PAH, yet little is known about the phenotypical presentation of this mutation. OBJECTIVE: This article reviews the pattern of chest CT findings in pediatric patients with PAH and TBX4 mutations and compares their radiographic presentation with those of age-matched patients with PAH but without TBX4 mutations. MATERIALS AND METHODS: A retrospective chart review of the pulmonary arterial hypertension database was performed. Pediatric patients with PAH-confirmed TBX4 mutations and an available high CT were included. Fifteen (9 females) patients met the inclusion criteria. Fourteen (8 females) age-matched controls with diagnosed PAH but without TBX4 mutations were also evaluated. The median age at diagnosis was 7.4 years (range: 0.1-16.4 years). Demographic information and clinical outcomes were collected. CTs of the chest were reviewed for multiple airway, parenchymal, and structural abnormalities (16 imaging findings in total). Chi-square tests were used to compare the prevalence of each imaging finding in the TBX4 cohort compared to the control group. RESULTS: Patients with TBX-4 mutations had increased presence of peripheral or subpleural irregularity (73% vs 0%, P < 0.01), cystic lucencies (67% vs 7%, P < 0.01), and linear or reticular opacity (53% vs 0%, P < 0.01) compared to the control group. Ground glass opacities, bronchiectasis, and centrilobular nodules were not significantly different between the two patient groups (P > 0.05). CONCLUSION: TBX4 mutations have distinct imaging phenotypes in pediatric patients with PAH. Compared to patients without this mutation, patients with TBX-4 genes typically present with peripheral or subpleural irregularity, cystic lucencies, and linear or reticular opacity.

Radiation dose reduction using spectral shaping in pediatric non-contrast sinus CT.

BACKGROUND: CT is the standard imaging technique to evaluate pediatric sinuses. Given the potential risks of radiation exposure in children, it is important to reduce pediatric CT dose and maintain image quality. OBJECTIVE: To study the utility of spectral shaping with tin filtration to improve dose efficiency for pediatric sinus CT exams. MATERIALS AND METHODS: A head phantom was scanned on a commercial dual-source CT using a conventional protocol (120 kV) and a proposed 100 kV with a 0.4-mm tin filter (Sn100 kV) protocol for comparison. Entrance point dose (EPD) of eye and parotid gland region was measured by an ion chamber. Sixty pediatric sinus CT exams (33 acquired with 120 kV, 27 acquired with Sn100 kV) were retrospectively collected. All patient images were objectively measured for image quality and blindly reviewed by 4 pediatric neuroradiologists for overall noise, overall diagnostic quality, and delineation of 4 critical paranasal sinus structures, using a 5-point Likert scale. RESULTS: Phantom CTDIvol from Sn100 kV is 4.35 mGy, compared to CTDIvol of 5.73 mGy from 120 kV at an identical noise level. EPD of sensitive organs decreases in Sn100 kV (e.g., right eye EPD 3.83±0.42 mGy), compared to 120 kV (5.26±0.24 mGy). Patients in the 2 protocol groups were age and weight (unpaired T test P>0.05) matched. The patient CTDIvol of Sn100 kV (4.45±0.47 mGy) is significantly lower than 120 kV (5.56±0.48 mGy, unpaired T test P<0.001). No statistically significant difference for any subjective readers' score (Wilcoxon test P>0.05) was found between the two groups, indicating proposed spectral shaping provides equivalent diagnostic image quality. CONCLUSION: Phantom and patient results demonstrate that spectral shaping can significantly reduce radiation dose for non-contrast pediatric sinus CT without compromising diagnostic quality.

Computed tomographic parenchymal lung findings in premature infants with pulmonary vein stenosis.

BACKGROUND: Developmental pulmonary vein pulmonary vein stenosis in the setting of prematurity is a rare and poorly understood condition. Diagnosis can be challenging in the setting of chronic lung disease of prematurity. High-resolution non-contrast chest computed tomography (CT) is the conventional method of evaluating neonates for potential structural changes contributing to severe lung dysfunction and pulmonary hypertension but may miss pulmonary venous stenosis due to the absence of contrast and potential overlap in findings between developmental pulmonary vein pulmonary vein stenosis and lung disease of prematurity. OBJECTIVE: To describe the parenchymal changes of pediatric patients with both prematurity and pulmonary vein stenosis, correlate them with venous disease and to describe the phenotypes associated with this disease. MATERIALS AND METHODS: A 5-year retrospective review of chest CT angiography (CTA) imaging in patients with catheterization-confirmed pulmonary vein stenosis was performed to identify pediatric patients (< 18 years) who had a history of prematurity (< 35 weeks gestation). Demographic and clinical data associated with each patient were collected, and the patients' CTAs were re-reviewed to evaluate pulmonary veins and parenchyma. Patients with post-operative pulmonary vein stenosis and those with congenital heart disease were excluded. Data was analyzed and correlated for descriptive purposes. RESULTS: A total of 17 patients met the inclusion criteria (12 female, 5 male). All had pulmonary hypertension. There was no correlation between mild, moderate, and severe grades of bronchopulmonary dysplasia and the degree of pulmonary vein stenosis. There was a median of 2 (range 1-4) diseased pulmonary veins per patient. In total, 41% of the diseased pulmonary veins were atretic. The right upper and left upper lobe pulmonary veins were the most frequently diseased (n = 13/17, 35%, n = 10/17, 27%, respectively). Focal ground glass opacification, interlobular septal thickening, and hilar soft tissue enlargement were always associated with the atresia of an ipsilateral vein. CONCLUSION: Recognition of the focal parenchymal changes that imply pulmonary vein stenosis, rather than chronic lung disease of prematurity changes, may improve the detection of a potentially treatable source of pulmonary hypertension, particularly where nonangiographic studies result in a limited direct venous assessment.

Early Anti-Tumor-Necrosis-Factor Therapy for Crohn's Disease-Related Abdominal Abscesses and Phlegmon in Children.

BACKGROUND: Internally penetrating Crohn's Disease complications, including abscesses and phlegmon, represent a high-risk Crohn's Disease phenotype. Anti-tumor-necrosis-factor-α (Anti-TNF) therapies are effective in treating penetrating Crohn's Disease and early initiation has shown unique benefits. However, timing of anti-TNF initiation in the setting of internally penetrating Crohn's Disease complications is typically heterogenous due to concern over precipitating serious infections. Recent studies demonstrate such an association may not exist. AIMS: We aimed to describe the multidisciplinary management of pediatric patients with internally penetrating Crohn's Disease complications, focusing on the utilization and timing of anti-TNF therapy relative to complication resolution and adverse events. METHODS: We performed a single-center retrospective cohort study of pediatric patients with internally penetrating Crohn's Disease complications from 2007 to 2021. The safety and effectiveness of anti-TNF therapy initiation prior to complication resolution was assessed by comparing rates of infectious and Crohn's Disease-related adverse events between those who received anti-TNF therapy prior to complication resolution, versus those who did not. RESULTS: Twenty-one patients with internally penetrating Crohn's Disease complications were identified. 7/21 received anti-TNF therapy prior to complication resolution. Infectious adverse events within 90 days of complication occurred in 0/7 patients initiating anti-TNF therapy prior to complication resolution and 10/14 patients who did not (p = 0.004). Crohn's Disease-related surgeries and hospitalizations within 1 year of complication occurred in 12/20 patients, with similar frequency between groups. CONCLUSIONS: Initiating anti-TNF therapy prior to internally penetrating Crohn's Disease complication resolution may be a safe and effective strategy to improve clinical outcomes.

Computed Tomographic Angiography Provides Reliable Coronary Artery Evaluation in Infants With Pulmonary Atresia Intact Ventricular Septum.

Evaluate the use of coronary CTA as an initial assessment for determining Right Ventricle Dependent Coronary Circulation (RVDCC) in neonates with Pulmonary Atresia with Intact Ventricular Septum (PA IVS). Retrospective review of cases with coronary CTA and compare with available catheter angiography, pathology, surgical reports, and outcomes from Mar 2015 to May 2022. In our cohort of 16 patients, 3 were positive for RVDCC, confirmed by pathologic evaluation, and there was concordance for presence or absence of RVDCC with catheter angiography in 5 patients (4 negatives for RVDCC, 1 positive). Clinical follow up for the 8 patients that underwent RV decompression had no clinical evidence of myocardial ischemia. Our findings suggest that coronary CTA is reliable as first-line imaging for determination of RVDCC in neonates with PA IVS. These findings, if supported by further prospective study, may reserve invasive coronary angiography for cases with diagnostic uncertainty or at the time of necessary transcatheter interventions.

Chest computed tomography findings of ground-glass nodules with enhancing central vessel/nodule in pediatric patients with BMPR2 mutations and plexogenic arteriopathy.

BACKGROUND: Germline mutation in bone morphogenetic protein type II (BMPR2) is the most common cause of idiopathic/heritable pulmonary hypertension in pediatric patients. Despite the discovery of this gene there are no known descriptions of the CT or CT angiography findings in these children. OBJECTIVE: To correlate the clinical presentation, pathology and chest CT findings in pediatric patients with pulmonary hypertension caused by mutations in the BMPR2 gene. MATERIALS AND METHODS: We performed a search to identify pediatric patients with a BMPR2 mutation and CT or CT angiography with the clinical history of pulmonary hypertension. Three pediatric radiologists reviewed the children's CT imaging findings and ranked the dominant findings in order of prevalence via consensus. RESULTS: We identified three children with pulmonary hypertension and confirmed germline BMPR2 mutations, two of whom had undergone lung biopsy. We then correlated the imaging findings with histopathology and clinical course. CONCLUSION: All of our patients with BMPR2 mutations demonstrated a distinct CT pattern of ground-glass nodules with a prominent central enhancing vessel/nodule. These findings correlated well with the pathological findings of plexogenic arteriopathy.

Vaping and diffuse alveolar hemorrhage: All EVALI is not created equal.

E-cigarette, or vaping product, use associated lung injury (EVALI) refers to respiratory illness in patients with recent vaping and no signs of infection or underlying illness. EVALI can cause severe acute respiratory distress syndrome and death. A spectrum of diagnoses can fit the description of EVALI since it relies heavily on nonspecific, radiographic findings. We present a rare case of EVALI in which a patient with a history of vaping presented with acute hypoxemia and was diagnosed with diffuse alveolar hemorrhage (DAH). The mechanism of injury of DAH due to vaping is unknown, and further research into the topic is required.

Ground glass and fibrotic change in children with surfactant protein C dysfunction mutations.

INTRODUCTION: Therapeutics exist to treat fibrotic lung disease in adults, but these have not been investigated in children. Defining biomarkers for pediatric fibrotic lung disease in children is crucial for clinical trials. Children with surfactant protein C (SFTPC) dysfunction mutations develop fibrotic lung disease over time. We evaluated chest computed tomography (CT) changes over time in children with SFTPC dysfunction mutations. METHODS: We performed an institutional review board-approved retrospective review of children with SFTPC dysfunction mutations. We collected demographic and clinical information. Chest CT scans were evaluated using visual and computerized scores. Chest CT scores and pulmonary function tests were reviewed. RESULTS: Eleven children were included. All children presented in infancy and four children suffered from respiratory failure requiring mechanical ventilation. Those who performed pulmonary function tests had stable forced vital capacities over time by percent predicted, but increased forced vital capacity in liters. CT findings evolved over time in most patients with earlier CT scans demonstrating ground glass opacities and later CT scans with more fibrotic features. In a pilot analysis, data-driven textural analysis software identified fibrotic features in children with SFTPC dysfunction that increased over time and correlated with visual CT scores. DISCUSSION: We describe 11 children with SFTPC dysfunction mutations. Increases in forced vital capacity over time suggest that these children experience lung growth and that therapeutic intervention may maximize lung growth. Ground glass opacities are the primary early imaging findings while fibrotic features dominate later. CT findings suggest the development of and increases in fibrotic features that may serve as potential biomarkers for antifibrotic therapeutic trials.

Vascular and pulmonary comorbidities in children with congenital EA/TEF.

BACKGROUND: Esophageal atresia with tracheoesophageal fistula (EA/TEF) is associated with many congenital and vascular malformations; however, reports utilizing computed tomography (CT) and computed tomography angiography (CTA) are limited. The objective of this study is to review CT scans of the chest from patients with EA/TEF and report their pulmonary and vascular findings. METHODS: We completed a retrospective chart review of children with congenital EA/TEF evaluated in the aerodigestive clinic at Children's Hospital Colorado. Results of the most recent CTA or CT of the chest were investigated. Demographics, medical conditions, and bronchoscopy findings were also recorded. The ratio of tracheal lumen area between inspiratory and expiratory CTA images was measured. RESULTS: Of the patients with congenital EA/TEF seen in the program, 47 patients had a chest CT available for review. Eight patients (17%) had bronchiectasis. Of the contrast CT scans, 15 (58%) had a vascular abnormality and 16 (62%) demonstrated tracheal compression (38% at the level of the innominate artery, 35% from other structures). Nineteen of the CTAs had volumetric expiratory images of the trachea to evaluate tracheomalacia. The mean expiratory:inspiratory area was 0.57 (SD ± 0.23) at the level of the innominate. CONCLUSION: Patients with EA/TEF frequently have vascular abnormalities that may alter airway mechanics as well as pulmonary comorbidities that may affect long-term management. For patients experiencing persistent respiratory symptoms, CTA of the chest should be considered adjunct to bronchoscopy to help with medical and surgical management of these children.

Prognostic relevance and inter-observer reliability of chest-imaging in pediatric ARDS: a pediatric acute respiratory distress incidence and epidemiology (PARDIE) study.

PURPOSE: Definitions of acute respiratory distress syndrome (ARDS) include radiographic criteria, but there are concerns about reliability and prognostic relevance. This study aimed to evaluate the independent relationship between chest imaging and mortality and examine the inter-rater variability of interpretations of chest radiographs (CXR) in pediatric ARDS (PARDS). METHODS: Prospective, international observational study in children meeting Pediatric Acute Lung Injury Consensus Conference (PALICC) criteria for PARDS, which requires new infiltrate(s) consistent with pulmonary parenchymal disease, without mandating bilateral infiltrates. Mortality analysis focused on the entire cohort, whereas inter-observer variability used a subset of patients with blinded, simultaneous interpretation of CXRs by intensivists and radiologists. RESULTS: Bilateral infiltrates and four quadrants of alveolar consolidation were associated with mortality on a univariable basis, using CXRs from 708 patients with PARDS. For patients on either invasive (IMV) or non-invasive ventilation (NIV) with PaO2/FiO2 (PF) ratios (or SpO2/FiO2 (SF) ratio equivalent) > 100, neither bilateral infiltrates (OR 1.3 (95% CI 0.68, 2.5), p = 0.43), nor 4 quadrants of alveolar consolidation (OR 1.6 (0.85, 3), p = 0.14) were associated with mortality. For patients with PF ≤ 100, bilateral infiltrates (OR 3.6 (1.4, 9.4), p = 0.01) and four quadrants of consolidation (OR 2.0 (1.14, 3.5), p = 0.02) were associated with higher mortality. A subset of 702 CXRs from 233 patients had simultaneous interpretations. Interobserver agreement for bilateral infiltrates and quadrants was "slight" (kappa 0.31 and 0.33). Subgroup analysis showed agreement did not differ when stratified by PARDS severity but was slightly higher for children with chronic respiratory support (kappa 0.62), NIV at PARDS diagnosis (kappa 0.53), age > 10 years (kappa 0.43) and fluid balance > 40 ml/kg (kappa 0.48). CONCLUSION: Bilateral infiltrates and quadrants of alveolar consolidation are associated with mortality only for those with PF ratio ≤ 100, although there is high- inter-rater variability in these chest-x ray parameters.

Tracheal and lower airway changes in a patient with mucolipidosis type II.

INTRODUCTION: Mucolipidosis type II (MLII) is a lysosomal storage disease causing systemic deposition of mucopolysaccharides. We describe imaging and bronchoscopy findings not previously reported in the literature in a child with MLII. CASE: A 9-year-old with MLII s/p hematopoietic stem-cell transplant (HSCT), bronchiectasis, and aspiration presented with recurrent respiratory illnesses. Bronchoscopy and chest computed tomography were performed, showing a saber-sheath trachea with fixed narrowing and curvature. DISCUSSION: This case describes potentially life-threatening airway distortion in MLII despite HSCT that cannot be ameliorated with tracheostomy. Etiology is unknown but likely due to abnormal deposition causing an immobile, stenotic airway and restricted thorax.

Marijuana medusa: The many pulmonary faces of marijuana inhalation in adolescent males.

Marijuana use has risen dramatically over the past decade. Over this same time period, pediatric hospitals have seen an increase in presentation of adolescents with acute respiratory symptoms after recent marijuana inhalation. We report a case series of three adolescent males with significant findings of bilateral pulmonary nodules and ground glass opacities on chest imaging associated with recent marijuana inhalation. Lung biopsies in two of the three patients confirmed silica-induced pneumoconiosis. The third patient was diagnosed with acute hypersensitivity pneumonitis without lung biopsy. Improvement in clinical symptoms and lung function testing were noted in two of three patients after marijuana inhalation cessation. This case series highlights the variety of severe pulmonary presentations in adolescents following recent marijuana inhalation. Future studies are required to assess whether these presenting pulmonary complications are from direct marijuana exposure or indirect associations with marijuana inhalation injuries.

Pulmonary interstitial glycogenosis: Diagnostic evaluation and clinical course.

OBJECTIVES: We sought to describe the phenotype for patients with P.I.G. including presentation, evaluation, cardiac co-morbidities, high resolution computed tomography findings, and outcomes. METHODS: With institutional review board approval, we performed a retrospective review of patients with biopsy-proven P.I.G. Biopsies, high resolution chest computed tomography, and cardiac evaluations were reviewed and characterized by experts in each field. RESULTS: Sixty-two percent of the patients were male. The median gestational age was 37 weeks (range 27-40). The median age at biopsy was 1.6 months (range 0.3-6 months). Structural heart disease was present in 63% of patients. Pulmonary hypertension (diagnosed by echocardiogram and/or cardiac catheterization) was noted in 38% of patients. Alveolar simplification was present in 79% of patients. Fifty percent of available biopsies revealed patchy disease. An increase in age at biopsy was associated with patchy (vs diffuse) disease. Ninety-two percent of patients were treated with systemic corticosteroids. Median age at last follow-up was 1234 days with a range of 37 days to 15 years. At the time of last follow-up, 12 patients were off all support, eight were on supplemental oxygen, two were mechanically ventilated, one underwent lung transplantation, and one died. CT findings commonly included ground glass opacities (86%) and cystic change (50%). CONCLUSIONS: The P.I.G. phenotype has not been comprehensively described, and poor recognition and misconceptions about P.I.G. persist. P.I.G. is a disease that presents in early infancy, requires significant medical intervention, and frequently is seen in association with alveolar simplification and/or cardiovascular disease. CT findings include ground glass opacities and cysts. Patients should be monitored for pulmonary hypertension. Without life-threatening comorbidities, many patients do well over time, although respiratory symptoms may persist into adolescence.

Lung and airway shape in neuroendocrine cell hyperplasia of infancy.

BACKGROUND: Neuroendocrine cell hyperplasia of infancy (NEHI) is a rare lung disease associated with significant air trapping. Although chest CT is crucial in establishing a diagnosis, CT and biopsy findings do not reveal airway abnormalities to explain the air trapping. OBJECTIVE: We compared lung and airway morphology obtained from chest CT scans in children with NEHI and control children. In the children with NEHI, we explored relationships between lung and airway shape and lung function. MATERIALS AND METHODS: We performed a retrospective review of children with NEHI who underwent clinical chest CT. We identified control children of similar size and age. We created lung masks and airway skeletons using semi-automated software and compared them using statistical shape modeling methods. Then we calculated a logistic regression model using lung and airway shape to differentiate NEHI from controls, and we compared shape model parameters to lung function measurements. RESULTS: Airway and lung shapes were statistically different between children with NEHI and controls. We noted a broad lung apex in the children with NEHI and a significantly increased apical anterior-posterior lung diameter. A logistic regression model including lung shape was 90% accurate in differentiating children with NEHI from controls. Correlation coefficients were significant between lung function values and lung and airway shape. CONCLUSION: Lung and airway shapes were different between children with NEHI and control children in this cohort. Children with NEHI had an increased anteroposterior diameter of their lungs that might be useful in the diagnostic criteria.

High-resolution CT findings of pulmonary interstitial glycogenosis.

BACKGROUND: Pulmonary interstitial glycogenosis is a form of childhood interstitial lung disease characterized by the histological finding of abundant glycogen-laden mesenchymal cells within the pulmonary interstitium. Patients present in the neonatal period with disproportionate respiratory distress. Often, pulmonary interstitial glycogenosis is accompanied by alveolar simplification complicating recognition and diagnosis. Despite the recognition of pulmonary interstitial glycogenosis as a distinct entity, only a few case reports describing imaging findings are found in the literature, with no published systematic review available. OBJECTIVE: The purpose of this review is to provide a review of CT findings of pulmonary interstitial glycogenosis with histological correlation to aid in early diagnosis and management. MATERIALS AND METHODS: A 10-year retrospective review was performed to identify pediatric patients <18 years who underwent biopsy and CT within the last 10 years at our institution. The inclusion criteria include patients who had a CT within 3 months of biopsy and pathology-proven pulmonary interstitial glycogenosis CTs that were evaluated by three radiologists using a standardized scoring system. RESULTS: Fifteen patients met inclusion criteria (9 male, 6 female). At the time of initial pre-biopsy CT, ages ranged from 2 weeks to 5 months. Pulmonary symptoms presented at birth in the majority of patients (n=13). Two patients presented in early infancy at 3 months (n=1) and 5 months (n=1). Ground glass opacities were the most common CT finding (n=14), which varied from diffuse to scattered. Cystic lucencies (n=11) were noted in the majority of patients as well. Interlobular septal thickening (n=10) and architectural distortion (n=8) were less common findings. CONCLUSION: The most common CT findings of pulmonary interstitial glycogenosis are ground glass opacities with cystic lucencies. While the imaging findings are distinct from the typical presentation of neuroendocrine hyperplasia of infancy, there is significant overlap of these findings with surfactant dysfunction mutations, entities that also present with respiratory distress in the neonatal period. Therefore, imaging findings in pulmonary interstitial glycogenosis are helpful in guiding the need for genetic testing and/or biopsy.

HRCT findings of childhood follicular bronchiolitis.

BACKGROUND: Follicular bronchiolitis is a lymphoproliferative form of interstitial lung disease (ILD) defined by the presence of peribronchial lymphoid follicles. Follicular bronchiolitis has been associated with viral infection, autoimmune disease and immunodeficiency. The most common clinical manifestation is respiratory distress in infancy followed by a prolonged course with gradual improvement. We found no reports of systematic review of high-resolution computed tomography (HRCT) findings in pediatric follicular bronchiolitis. OBJECTIVE: The purpose of this study was to describe the HRCT findings of follicular bronchiolitis in children and correlate these imaging findings with histopathology. MATERIALS AND METHODS: A 5-year retrospective review of all pathology-proven cases of follicular bronchiolitis was performed. Inclusion criteria were age <18 years and an HRCT within 6 months of lung biopsy. HRCTs were reviewed by three observers and scored using the system previously described by Brody et al. RESULTS: Six patients met the inclusion criteria with age range at HRCT of 7-82 months (median: 39.5 months). Pulmonary nodules (n=6) were the most common HRCT finding followed by focal consolidation (n=5), bronchiectasis (n=4) and lymphadenopathy (n=3). Tree and bud opacities and nodules on CT correlated with interstitial lymphocytic infiltrates and discrete lymphoid follicles on pathology. CONCLUSION: The salient HRCT findings of childhood follicular bronchiolitis are bilateral, lower lung zone predominant pulmonary nodules and bronchiectasis with infantile onset of symptoms. These characteristic HRCT findings help differentiate follicular bronchiolitis from other forms of infantile onset ILD.