Noticeable confusion has existed regarding the nomenclature, classification, and management of pediatric diffuse lung diseases [9]. In this study, CLD was classified as inhalation lung disease, chronic recurrent inflammatory, autoimmune disease, chronic airway disease, ILD, hereditary malformations, and vascular disease.
The Bhalla score, first proposed by Bhalla et al., was created to adjust for pulmonary structural damage observed on MDCT in pediatric cases diagnosed with CF in the year 1991 [6]. Thereafter, Judge et al. proposed modifications to the score by including more CT features described in the disease, namely mosaic attenuation/perfusion, air trapping, acinar nodule, intralobular septal thickening, and ground-glass infiltrate [8]. In the current study, the significance of CT scores in inflammatory and inhalation lung diseases suggests the utility of this scoring system for such entities as well.
The American Thoracic Society classified Childhood interstitial lung disease (chILD) by the age-group from infancy to later childhood presentation [10]. In the current study, 34 patients (75.6%) were diagnosed as chILD with mainly later childhood presentation, including inhalation, post-inflammatory, aspiration pneumonitis, autoimmune diseases, and ILD (including infants with NEHI and children with UIP, NSIP, and hemosiderosis). Clinical evaluation through further tests, such as high-resolution CT, spirometer tests, bronchoalveolar lavage, and biopsy, is needed [10].
Aspiration syndrome (Fig. 4) is a common finding in children with recurrent lower respiratory tract infections and is predicted to be present in 26–49% of children with chILD. One study showed consolidation or airway changes in the dependent and basal portions of both lungs on CT [11]. In the current study, aspiration syndrome was reported in 7 (11%) of the cases and 20.6% of chILD cases. Moreover, variable CT features had been observed among those with aspiration syndrome, which ranged from patchy ground-glass densities in 66.7%, bronchiectasis in 66.7%, and collapse in 33.3%. Moreover, those with aspiration syndrome had a disease located in the apical segment of both lower lobes (LL), with 50% showing diffuse LL involvement and 33.3% showing middle lobe and lingula involvement. Regarding disease incidence, a study by Deutsch et al. showed that only 1.7% of chILD cases were diagnosed with aspiration syndrome. However, the CT chest findings presented herein were consistent with those presented in a study conducted by Tanaka et al. wherein MDCT in 85 children diagnosed with aspiration syndrome revealed no significant correlation between aspiration syndrome and all CT features, except for bronchial wall thickening and atelectasis [12].
Neuroendocrine cell hyperplasia (NEHI) has been found to present more frequently among males in the first 2 years of life. MDCT, which has a sensitivity of 78% and specificity of 100% for NEHI, typically shows a mosaic attenuation pattern affecting at least four lobes with geographic ground-glass opacities that are most conspicuous on the right middle lobe and lingula and areas of hyperlucency associated with air trapping. Confirmatory biopsy may not be necessary for patients with a classic clinical presentation and characteristic radiologic findings [10]. The study by Deutsch et al. showed that NEHI was diagnosed in 10% of chILD cases [9]. These findings were consistent with our clinical and radiological data on confirmed NEHI cases, although they accounted for only 2.9% of our chILD cases (Fig. 5).
There are several causes of lung hemorrhage, including vasculitis, good pasture syndrome, and systemic lupus erythematosus. In the acute phase, CT findings show an ill-defined fluffy appearing centrilobular ground glass that represents diffuse alveolar hemorrhage. With repeated hemorrhage, mild interstitial fibrosis has been found to cause interlobular septal thickening [10]. In the current study, similar changes were noted in a single case with repeated hemorrhage, who developed pulmonary alveolar hemosiderosis.
Langerhans cell histiocytosis is one of the chILD diseases that is not specific to infancy, with portions of the systemic disease with pulmonary involvement presenting in 20–50% of the cases [10]. CT shows nodules of varying size and bizarre pulmonary cyst shapes, with upper lobe predominance [13]. This was consistent with our case diagnosed with Langerhans cell histiocytosis (Fig. 6).
Our findings showed that ILD was significantly correlated with the presence of lung honeycombing (P = 0.044), similar to the case with usual interstitial pneumonia (Fig. 7). This has been considered a common finding in fibrotic lung disease that leads to traction of bronchioles and formation of a honeycomb appearance. Studies have shown a significant correlation between ILD and honeycomb appearance on MDCT [14].
In the present study, 8.9% of the included cases presented with autoimmune disease, which was significantly correlated with bilateral lung affection and a higher number of emphysematous bullae. These findings were consistent with those presented in several studies including children diagnosed with systemic autoimmune disease, which found that autoimmune disease was significantly correlated with bilateral lung pathologies [15,16,17]. The presence of autoimmune lung disease had been commonly associated with pulmonary emphysema based on the available literature [18].
In the present cohort, the severity of lung disease and peribranchial thickening was significantly correlated with overall hereditary lung anomalies. These findings were consistent with those presented in studies conducted on children diagnosed with cystic fibrosis, which revealed that children with hereditary malformations of the bronchial tree and ciliary dyskinesia were predisposed to severe manifestations of bronchiectasis [19, 20].
In the current study, the three cases (6.7%) who had CF all presented with variable severity of bronchiectasis and peribronchial thickening, with two showing air trapping, one showing mucus plug formation, and another case showing collapse and ground-glass attenuation (Fig. 8). Sasihuseyinoglu et al. showed that out of 36 patients, 96.4% exhibited peribronchial thickening, 50 showed mucus plug formation, and 32.1% exhibited collapse/consolidation. Emphysema was identified in 18 patients [21].
The current study showed that the total CT score was significantly correlated with the severity and extent of bronchiectasis, along with peribronchial thickening. These findings were consistent with those presented in a multicenter prospective observational study by Martínez-García et al. in 99 consecutive patients with moderate-to-severe bronchiectasis, who showed that the severity of CLD was significantly correlated with the Bhalla CT score [22]. Similarly, another study on the Bhalla score showed an almost ninefold increase in the risk of having malacia/obliterative-like combination lesions in the bronchial tree [23].
Mosaic perfusion/attenuation and intralobular septal thickening was significantly correlated with the presence of inflammatory processes in lungs (P = 0.008 and 0.004, respectively). These findings were confirmed by Teufel and his team, who stated that mosaic attenuation was significantly correlated with the presence of lung inflammation [24]. However, this was inconsistent with another study conducted on patients with wet cough, which showed that inflammation was not significantly associated with the total Bhalla score [25].
The present study showed that chronic airway disease was associated with bronchial disease in 77.8%, mucous plugging in 22.2%, mosaic attenuation in 33.3%, and centrilobular nodules in 55.6% and was significantly correlated with air trapping (P = 0.026) (Fig. 9). These findings were consistent with those presented in several studies conducted to evaluate the extent of expiratory air trapping on MDCT and spirometry, which concluded that air trapping was a prominent feature of chronic airway diseases, such as asthma and chronic bronchitis [26,27,28].
Thickening of the interlobular septa was found more frequently in cases with CLD mainly secondary to inflammatory and interstitial lung disease. One study showed that the prominent inflammatory infiltration into the submucosa of patients with idiopathic bronchiectasis might lead to lymphatic congestion and thus thickening of the interlobular septa [29].
The current study showed that 17.8% of cases exhibited respiratory distress, with a severity score ranging from 2 to 21, and that the clinical severity of symptoms was not correlated with the CT score. Douros et al. [23] stated that MDCT scanning detected airway wall thickening and bronchiectasis, with the severity of the findings correlating positively with the length of clinical symptoms. Moreover, they found that the clinical picture was incompatible with MDCT findings.
It is important for clinicians and radiologists to work collaboratively in the radiological assessment of the rising number of children with CLD in order to provide continuous management and utilize the most optimal radiological procedures to ensure accurate clinical diagnosis and appropriate management pathways [2].
This study was limited by the limited number of cases which is hindered by the available cases over the study timing.