THE EVOLUTION OF RADIOLOGICAL IMAGES IN A 4-MONTH-OLD INFANT WITH CONGENITAL PULMONARY AIRWAY MALFORMATION: A CASE REPORT

Congenital pulmonary airway malformation, formerly known as congenital cystic adenomatoid malformation, is a heterogeneous group of cystic and non-cystic pulmonary lesions marked with the overgrowth of primary bronchioles, which is associated with an abnormal bronchial tree that does not have cartilage. A 4-month-old boy came with a complaint of productive coughs since he was 3 weeks old, fever since the age of 2 months, and shortness of breath. The patient was once hospitalized due to pneumonia and suspected tuberculosis. After undergoing serial chest radiographs, the results showed multiple cysts that were dominant in the lower lobe of both lungs with surrounding infiltrates. Through the confirmation of a chest CT scan, there were small, multiple cysts with a size of <2 cm in both lungs, connected to the bronchial branch, accompanied by consolidation with an air bronchogram suggestive of type 2 congenital pulmonary airway malformation. Congenital pulmonary airway malformation is a rare case that usually requires serial chest radiographs to assist in the establishment of its diagnosis and a CT scan for a definitive diagnosis of its lesions.


INTRODUCTION
Congenital lung anomalies, a heterogeneous group of developmental disorders with widely varying clinical and imaging manifestations, range from abnormal lung with normal vasculature, to abnormal lung and vasculature, to normal lung with abnormal vasculature. There have been improvements in the detection of congenital lung anomalies using prenatal imaging, be it US or MRI. Congenital pulmonary airway malformation (CPAM) is the one most commonly observed, accounting for 30-40% of all congenital lung anomalies. (1,2,3)

CASE DESCRIPTION
A 4-month-old boy (BW at 4.1 kg and BL at 57 cm) was referred from a type B hospital with complaints of recurrent productive cough since he was 3 weeks old, without signs of a runny nose. Ever since the patient was 2 months old, he's had fever on a daily basis with temperatures ranging from 37.5-39.5°C. The fever was experienced particularly in the morning. The patient also complained of loose stools 4 days before hospital admission, with a volume of ¼ to ½ a glass and a frequency of 4-5 times/day. His body weight decreased by 3 ounces within 2 months. At the age of 2 months, he was hospitalized for 10 days at a type B hospital for pneumonia and pulmonary TB.
The patient was treated and received OAT. One day after his discharge, the patient had a fever and was hospitalized at a type B hospital for 14 days due to pneumonia and was resuscitated because of cardiac and respiratory arrest and was referred to Saiful Anwar Hospital. The patient was born spontaneously at term at a midwife with a birth body weight of 3,000 grams, and there was a breathing problem but without cyanosis. He did not immediately cry. The patient consumed breast milk and formula milk since birth. His mother underwent https://ijri.ub.ac.id/ International Journal of Radiology and Imaging. 02. (01). 27 Juni 2023: 7-13  e-ISSN 2830-506X  p-ISSN 2830-6007 routine ANC at the midwife with complaints of prolonged cough but was left unchecked by the doctor.
Based on the physical examination upon hospital admission, there was spontaneous breathing with O2 support. The patient was acyanotic with a fever (38°C) and a cough. From his respiratory system examination, the patient's respiratory rate was 40-50 times/minute, SaO2 was 98%, and there were subcostal retractions and rhonchi in both lungs. However, other organs were within normal limits. The patient's anthropometric status indicated marasmic malnutrition.
Laboratory tests regarding complete blood count revealed anemia (Hb at 9.3 g/dL) with hematocrit at 29%. The GeneXpert MTB test of his stool sample showed a highly positive result.
Chest radiograph upon hospital admission (April 7, 2019) suggests partially consolidated infiltrates on both lung fields and right perihilar lobulated consolidation that can be concluded as pulmonary TB and right perihilar lymphadenopathy. According to the evaluation of the chest radiograph on April 15, 2019, multiple small cavities began appearing on both lung fields with persistent infiltrates. Furthermore, on the evaluation of the chest radiograph on May 2, 2019, there were multiple cavities on both lung fields with larger sizes compared to the previous photo, predominantly in the lung base with fewer infiltrates. The chest radiograph evaluation on May 10, 2019, depicted multiple cavities with infiltrates that are similar in appearance to the previous photo. The patient was diagnosed with pneumonia and bilateral pulmonary multiple cystic lesions suggesting CPAM. Subsequently, the patient underwent a chest CT scan with contrast on May 14, 2019, revealing small, multiple air-filled cysts (the largest diameter was < 2 cm) on both lungs, which some connect to the bronchial branch and accompanied by consolidation with air bronchogram surrounding it. There were still visible remnants of normal parenchyma. From the chest CT scan, the result was suggestive of features of type 2 CPAM.
Even though, at the beginning of treatment, the patient momentarily experienced respiratory distress, his condition gradually improved. The patient received treatments consisting of antibiotics, antifungals, OAT, paracetamol, and vitamins.

DISCUSSION
CPAM is a heterogeneous group of cystic and non-cystic pulmonary lesions marked with the overgrowth of the primary bronchioles, which is connected to an abnormal bronchial tree that does not have cartilage. (2,4,5) The term CPAM is preferable to congenital cystic adenomatoid malformation because cystic lesions are only found in 3 of the 5 types of lesion, while adenomatoid is only in 1 type (type 3). (1,4) The incidence is roughly 1 out of 25,000-35,000; however, this figure may not be entirely representative due to limited access to antenatal imaging and operator dependence in antenatal US. (6,7) Vascularization in this lesion usually originates from the pulmonary arteries with drainage through the pulmonary veins, except hybrid lesions, in which the blood supply is systemic. (1,2,3) CPAM is classified by Stocker et al. into 5 types based on cyst size and histological similarity to the growth of the bronchial tree and airspace. Type 0 originates from the trachea or bronchus, presenting with severe acinar dysgenesis or dysplasia of large airways that involves the entire lung lobe and is generally lethal. Type 1 (large cyst type) originates from the bronchus or the bronchioles, approximately 60-65% of all CPAM lesions. This type is marked with solitary or multiple macrocysts that are 2-10 cm in size. Type 2 (small cyst type) originates from the bronchioles, accounting for 20-40%. In this type, there are small, multiple cysts that are about 0.5-2 cm in size. There is an association (50%) with other abnormalities such as bilateral renal agenesis, cardiovascular malformations, diaphragmatic hernia, and extralobar pulmonary sequestration. Type 3 (microcystic or solid type, also known as adenomatoid type) originates from the bronchioles-alveolar ducts, accounting for approximately 10%. The lesions are mostly solid with microcysts ≤5 mm in size identifiable histologically. Type 4 has a distal acinar origin. This type is difficult to distinguish from predominantly cystic pleuropulmonary blastoma on imaging, as it appears as large air-filled cysts. In other words, there are only three types of CPAM identifiable through imaging: types 1, 2, and 3. (1)(2)(3)(4)(5)(7)(8)(9) The time of CPAM diagnosis varies; it may be prenatal, postnatal, during infancy, or, rarely, adolescent and young adulthood. The spectrum of its clinical manifestations ranges from asymptomatic, to symptoms of respiratory infections, to severe acute respiratory distress. (8, [10][11][12] Patients with CPAM generally show symptoms early in their infancy, between the neonatal period and the age of 2 years, particularly respiratory distresses or recurrent infections. Older-aged children may present with continuous recurrent infections. However, CPAM may remain asymptomatic throughout childhood and may appear as incidental detection upon imaging in adulthood. (1,2,11) In our patient, he complained of a cough since he was at the age of 3 weeks to the point where he is required to be hospitalized repeatedly due to recurrent infections. Imaging plays a crucial role in detecting and diagnosing congenital pulmonary malformations, both in asymptomatic and symptomatic children. CPAM is easily detectable through prenatal imaging modalities, both US and MRI, which allow for the evaluation of the size of lesions and the compressive effects such as pulmonary hypoplasia, and sometimes even the categorization of these lesions into certain types. (2,13,14) Prenatal imaging can be carried out in the second trimester of pregnancy (21-24 weeks). (6,13,15) Among patients diagnosed antenatally, 70% of patients do not exhibit symptoms upon birth, and the remaining 30% experience neonatal respiratory distress-10% of whom require ventilation support due to severe respiratory distress. (15) Due to its short acquisition times and high spatial resolution, CT scan is the gold standard for detection in pre-operative patients postnatally. (16,17) The chest radiograph is commonly the primary imaging modality undertaken during the postnatal period. Similar to prenatal imaging, the manifestation in postnatal imaging depends on the underlying CPAM type. Type 1 appears as a solid, cystic mass with a cyst size of > 2 cm in the chest radiograph. If manifesting as a large, solitary cystic-dominant lesion, type 1 CPAM may be mistaken for congenital lobar hyperinflation (CLH). Type 2 appears as a smaller, but solid cystic lesion without lobar predilection. Moreover, type 2 presents radiographically as a focal area of persistent consolidation. Type 3 appears as a solid-appearing lesion and is indistinguishable from other congenital solidappearing lesions. As mentioned previously, type 4 appears as a large cystic lesion, is indistinguishable from predominantly cystic pleuropulmonary blastoma, and may be associated with pneumothorax and lobar hyperexpansion. (2,4,9) In our patient, features of cystic lesions can be seen more clearly during a serial evaluation of chest radiographs. The early chest radiograph only depicted infiltrates in both lungs, suggesting a process of infection. On the chest radiograph evaluation, multiple cystic lesions < 2 cm in size were able to be observed, which were in accordance with features of type 2 CPAM.
Advanced imaging using a CT scan generally follows the appearance of a lesion as seen on radiographs with a cross-sectional view. On a CT scan, type 1 is depicted as single or multiple large cystic lesions filled with air or with an air-fluid level. Type 2 presents as a multicystic lesion filled with air or an area of consolidation with non-specific margins or that is focal. Type 3 generally appears solid because the microcystic component can only be presented histologically. (2)(3)(4)(5) The location and extent of CPAM should be reported since they are essential for tclinical management and prospective surgical approach. (16) CPAM usually involves one lobe, (4,13,18) with a predilection of the lower lobe. (3,8,9,13,19) CPAM may resemble pneumonia or pulmonary abscess as a result of superimposed infection. (3,4) Our patient underwent a chest CT scan confirmation, and there seemed to be multiple cysts with the largest diameter of < 2 cm in both lungs, which were dominant in the lower lobe and partially connected to the bronchial branch along with consolidation surrounding it, supporting the appearance of type 2 CPAM. In a study conducted by Lee et al., of the 18 patients, 14 patients presented with CPAM in the lower lung lobe. (12) The prognosis of CPAM depends on the type and size of the lesion, underdevelopment of the related lung(s), and other relevant congenital anomalies. The prognoses of types 2 and 3 are not as favorable as that of type 1 because of their correlation with other congenital anomalies. (2,18,20) During antenatal imaging, there is a prognostic parameter known as CAM volume ratio (CVR), which compares the volume of the tumor to the fetal head circumference as a standardization of tumor growth relative to gestational age. (6,14,15) Prenatal management of choice includes the administration of steroids to the mother, minimally invasive procedures, or open fetal operation. (7,14,15) These interventions aim to relieve the effects of the mass, prevent the progressivity of any complications, and improve the prognosis of the fetus. (7,14) Postnatal management is divided into symptomatic patients and asymptomatic patients. For symptomatic patients, surgical resection is undertaken, either through lobectomy or segmentectomy, although currently, the thoracoscopy approach is frequently carried out. (2,14,15) Newborns with a large lesion may even necessitate surgical resection to preserve healthy lung parenchyma and restore the deviated mediastinum. (7) The management of asymptomatic patients remains controversial, with two possible approaches: the conservative approach (watch and wait) and prophylactic surgical resection, as there has yet to be a consensus made regarding the optimal time for an operation. (7,9,14,17) Despite this, elective surgical resection is commonly performed due to the risk of recurrent infection, hemorrhage, pneumothorax, and a small risk of malignancy. (2,6,9,14) To date, there is no standard management guideline and, as a consequence, management for CPAM depends on the clinician's preference. (10,11) In our patient, there was a symptom of respiratory distress. However, surgery was not possible because of the size of the lesion. As a result, the patient received medication for his symptoms and infection processes, with visible improvements.
Following surgical removal of a congenital cystic lung lesion, the amount of lung tissue removed, the existence of pulmonary hypoplasia, and compensatory lung growth all have a significant role in long-term respiratory performance. (17) Postoperative complications such as pneumonia, pneumothorax, and pectus excavatum may occur higher in pediatric CPAM patients who are symptomatic than those who are asymptomatic. (14,20) The risk of recurrent pneumonia may be persistent post-operation. Therefore, adequate vaccinations, antibiotic medication, and monitoring of lung functions are highly beneficial for long-term treatment. (20)