Diagnostic and Therapeutic Approaches to Pediatric Pulmonary Abscess: A Case Report

Introduction

Primary pulmonary abscess in pediatric patients is an infrequent condition with substantial variability in documented clinical presentation. Common manifestations include fever (100%), cough (75%), respiratory distress (50%), and chest or abdominal pain (50%), with a mean symptom duration of 13 days [1–4]. Although the anatomical distribution is heterogeneous, the left lower lobe is most frequently involved [5]. Key diagnostic modalities include chest radiography and computed tomography (CT), which allow detailed assessment of the extent and characteristics of the abscess [6,7]. Management strategies vary according to the underlying etiology. This report presents 2 clinical cases that illustrate different presentations of pulmonary abscess in pediatric patients, with the goal of promoting their analysis and discussion.

Case Reports

CASE 1:

A 4-year-old girl presented to the emergency department with a 3-day history of dry non-productive cough, 2 episodes of vomiting, and 2 episodes of liquid stools – both occurring on the day before admission – as well as a peak fever of 39.6°C on the previous day. The fever improved after 210 mg of acetaminophen had been administered by her mother. Relevant medical history included a complete immunization schedule, including BCG, pneumococcal, and Haemophilus influenzae type B vaccines; she had not received the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. She was the product of a first pregnancy, delivered vaginally at 39 weeks of gestation, with a birth weight of 3555 g and length of 55 cm. Neonatal adaptation was spontaneous, without the need for hospitalization or neonatal intensive care unit admission. There was no history of prior illness or exposure to tobacco smoke. On admission, the patient appeared in good general condition and was normotensive, tachycardic, and febrile. Pulmonary auscultation revealed crackles and decreased breath sounds over the left hemithorax. Vital signs were as follows: respiratory rate, 30 breaths/min (normal range: 20–30); heart rate, 128 beats/min (normal range: 80–120); blood pressure, 94/56 mmHg (p90=107/66); temperature, 36°C; and oxygen saturation, 93% while receiving 1 L/min of supplemental oxygen via nasal cannula, consistent with hypoxemia. Initial laboratory evaluation demonstrated leukocytosis with neutrophilia, in the absence of anemia and thrombocytopenia. The white blood cell count was 18 600/μL (normal range: 4500–12 500), with neutrophils at 13 800/μL, lymphocytes at 2400/μL, and monocytes at 2000/μL. The hemoglobin level was 11.5 g/dL (normal at sea level: 11.5–13.5 g/dL; adjusted for altitude, approximately 12.8–14.8 g/dL), hematocrit was 34.5% (normal range: 35–40%), and the platelet count was greatly elevated at 792 000/μL (normal range: 150 000–450 000). The C-reactive protein level was 2.5 mg/dL (normal: <10 mg/dL). Chest radiography revealed bilateral opacities with a central peribronchovascular distribution, bronchial wall thickening, and a focal area of consolidation in the posterior segment of the left lower lobe. Based on these findings, a diagnosis of community-acquired pneumonia involving the posterior segment of the left lower lobe was established. The patient was hospitalized; treatment with intravenous crystalline penicillin was initiated at a dose of 200 000 IU/kg/day after blood cultures had been obtained. During hospitalization, a torpid clinical course was observed; worsening respiratory status was associated with hypoxemia and abdominal pain. Supplemental oxygen was provided via low-flow nasal cannula. Thoracic ultrasonography demonstrated anechoic free fluid with mobile internal echoes at the left lung base, with an interpleural distance of 5 mm, accompanied by hepatization of the adjacent lung parenchyma and air bronchograms. In response to these findings, antimicrobial therapy was escalated to ceftriaxone (100 mg/kg/day) plus clindamycin (40 mg/kg/day). Clindamycin was discontinued after preliminary blood cultures remained negative at 48 h of incubation. On day 7 of hospitalization (day 4 of ceftriaxone therapy), daily fever spikes persisted. A respiratory FilmArray panel (BioFire Respiratory Panel 2.1, bioMérieux, Salt Lake City, UT, USA) identified adenovirus and Mycoplasma pneumoniae, prompting the addition of clarithromycin at a dose of 15 mg/kg/day. Persistent fever prompted a contrast-enhanced chest CT scan on hospital day 14 (Figure 1), which demonstrated a thick-walled cavitary lesion in the left lower lobe, predominantly involving the posterior basal and lateral basal segments. The cavity measured approximately 63×46×51 mm (volume, 77 mL) and contained both fluid and air; internal septation thickness reached 3 mm. After intravenous contrast administration, cavity wall enhancement was observed, along with adjacent ground-glass opacities. The lesion was surrounded by the left lower lobe pulmonary artery and vein; bronchial pathways to the affected segments were not clearly identified. Additionally, smooth thickening and enhancement of the left costal pleura were present, most pronounced in the mid-to-lower hemithorax. The pleural space was occupied by fluid-density material and a maximum interpleural separation of 13 mm, findings consistent with an associated empyema. Ceftriaxone therapy was thus continued. The patient was evaluated by pediatric surgery and interventional radiology teams, both of whom determined that surgical and percutaneous drainage were not indicated. The pediatric infectious diseases service reassessed the case and recommended ceftriaxone continuation at 100 mg/kg/day for a total of 21 days of inpatient therapy. The patient subsequently demonstrated favorable clinical progress, with resolution of systemic inflammatory response signs, successful discontinuation of supplemental oxygen, and transition to oral amoxicillin–clavulanate for an additional 14 days. She was discharged in stable condition and continued outpatient follow-up with pediatric infectious diseases. Follow-up evaluations at 2 and 6 months included chest radiographs that confirmed complete resolution of the pulmonary abscess and normalization of lung architecture. Clinically, the patient remained asymptomatic, with full recovery documented at both visits.

CASE 2:

A 17-month-old boy was referred to the emergency department from a secondary-level hospital due to a 15-day history of fever with spikes reaching 41.2°C, associated with non-bloody, non-mucoid diarrhea. His parents first sought medical attention on day 3 of illness, and a diagnosis of viral gastroenteritis was made; outpatient management was initiated. Due to the absence of clinical improvement and onset of respiratory symptoms, including non-cyanotic, non-emetic cough, nasal congestion, and rhinorrhea, the patient returned on day 6 of illness. Laboratory evaluation at that time demonstrated anemia without leukocytosis or neutrophilia, a normal platelet count, preserved renal function, and normal electrolyte and glucose levels. Urinalysis findings were not suggestive of infection. Physical examination documented findings consistent with acute otitis media, and amoxicillin treatment was prescribed for 3 days before discharge. Persistent fever, ongoing gastrointestinal and respiratory symptoms, and new signs of respiratory distress prompted a third visit on day 8 of illness. Hypoxemia was documented, and low-flow supplemental oxygen was initiated. Repeat laboratory tests revealed leukocytosis with neutrophilia, persistent normocytic and normochromic anemia, and a normal platelet count. Chest radiography demonstrated consolidation in the right upper and middle lobes, along with mixed infiltrates predominantly in the perihilar region, leading to suspicion of pneumonia. Treatment with amoxicillin plus ampicillin was initiated, along with inhaled therapy consisting of beclomethasone and salbutamol (2 puffs every 6 h). Chest CT performed due to persistent fever revealed bilateral pleural effusions; hypodense involvement of the right lower, middle, and upper lobes; and mediastinal lymphadenopathy – these findings were suggestive of pulmonary abscess. The patient was then referred to our institution for comprehensive management by pediatric subspecialties. His medical history was unremarkable. Immunizations were up to date for BCG, H. influenzae type B, and pneumococcus; he had not received the SARS-CoV-2 vaccine. The patient was the product of a first pregnancy and had been born at 40 weeks of gestation via uncomplicated vaginal delivery, with a birth weight of 2779 g and length of 49 cm. No neonatal intensive care unit admission was required at birth. On admission to our hospital, the patient was tachycardic, tachypneic, normotensive, and afebrile; pulmonary auscultation revealed crackles in both lung fields. Vital signs were as follows: respiratory rate, 42 breaths/min (normal range: 20–40); heart rate, 128 beats/min (normal range: 100–160); blood pressure, 94/56 mmHg (p90=104/63); temperature, 36°C; and oxygen saturation, 93% while receiving 1 L/min of supplemental oxygen via nasal cannula. Initial laboratory evaluation demonstrated leukocytosis, with a white blood cell count of 16 800/μL (normal range: 6000–17 500), including neutrophils at 11 500/μL and lymphocytes at 3990/μL. The hemoglobin level was reduced (9.4 g/dL; normal range: 10.5–13.5), with a hematocrit of 30% (normal range: 33–39), mean corpuscular volume of 77 fL, and mean corpuscular hemoglobin level of 24 pg. The platelet count was within normal limits at 353 000/μL (normal range: 150 000–450 000). The C-reactive protein level was 0.51 mg/dL (normal: <10 mg/dL). Given the diagnosis of complicated right-sided multilobar pneumonia, bilateral pleural effusions, and suspected pulmonary abscess, hospitalization was indicated. Intravenous ceftriaxone was continued. Blood cultures obtained at admission remained negative after 5 days of incubation, and no microbiological pathogen was isolated. Contrast-enhanced chest CT revealed a multiloculated, thick-walled, oval cavitary lesion occupying the entire right upper lobe, measuring 70×53×42 mm (volume, 81 mL); it demonstrated internal air–fluid levels and wall enhancement after contrast administration, findings consistent with a pulmonary abscess (Figure 2). A moderate right pleural effusion with pleural enhancement, suggestive of empyema, and associated right basal atelectasis were also observed. Mediastinal structures, vessels, and bronchi were otherwise unremarkable; no mediastinal lymphadenopathy was identified. The patient was evaluated by the pediatric surgery and interventional radiology teams, both of whom concluded that neither percutaneous drainage nor surgical intervention was indicated. Moreover, they stated that conservative medical management should be continued. The pediatric infectious diseases service recommended inpatient treatment with ceftriaxone for 14 days, followed by oral amoxicillin–clavulanate for an additional 14 days. The patient demonstrated progressive clinical improvement, including resolution of systemic inflammatory response signs and gradual discontinuation of supplemental oxygen, facilitating discharge. Outpatient follow-up at 3 and 6 months with the pediatric infectious diseases team confirmed that he remained asymptomatic, with complete resolution of symptoms, normalization of laboratory parameters, and radiological improvement consistent with full recovery.

Discussion

Community-acquired pneumonia, defined as an infectious disease of the respiratory system characterized by acute inflammation of alveolar spaces, has a substantial impact on the pediatric population and remains a highly common infectious condition in children [1]. Complications during the course of community-acquired pneumonia have been reported in up to approximately 25% of cases; they frequently include local processes such as pulmonary abscess, pleural effusion, and/or empyema [2]. Primary pulmonary abscess is a relatively rare entity in pediatric patients; in 1995, the estimated incidence was approximately 0.7 cases per 100 000 hospital admissions per year in the United States [3]. Published studies, although limited, indicate that the most common clinical manifestations of pulmonary abscess in children are fever (100%), cough (75%), chest or abdominal pain (50%), and respiratory distress (50%), with a mean symptom duration of 13 days [4,5]. The anatomical distribution of pulmonary abscess varies among reports. In some series, the right lower lobe has been described as the most frequently affected site, although left lower lobe involvement is often observed [4,7]. Typical chest radiographic findings include a cavitated mass, either isolated or within an area of adjacent parenchymal consolidation. An air–fluid level is often present, and the internal margins of the cavity are usually smooth. Initial suspicion is raised by chest radiography, with subsequent confirmation by CT, which allows differentiation of pulmonary abscess from other entities, such as empyema [8,9]. Identification of the causative organism in pediatric pulmonary abscess remains a major diagnostic challenge. Reported culture yields vary widely depending on the sampling technique, with rates of approximately 50% in some series and approaching 60% to 90% when invasive lower respiratory tract sampling methods (eg, CT-guided aspiration or thoracoscopic drainage) are used [8,10,11]. Importantly, specimens obtained from the upper respiratory tract and commonly used in rapid molecular panels, including nasopharyngeal swabs, do not reliably reflect lower respiratory tract microbiology – positive results may represent colonization, rather than true infection [12]. Therefore, pathogen detection from upper airway samples should be interpreted with caution because such findings may not accurately represent the etiology of lung parenchymal disease [12]. Given the difficulty of determining the causative etiology and guiding effective antimicrobial therapy, it remains essential to consider potential microbiological coinfections during the course of pneumonia and its complications, including pulmonary abscess.

Management of pulmonary abscess includes several therapeutic options, such as antimicrobial therapy, minimally invasive procedures including percutaneous drainage, and surgical intervention in selected cases. These approaches are not necessarily sequential and may be combined or tailored according to the patient’s clinical status and institutional practice. The duration of intravenous antimicrobial therapy typically ranges from 3 to 8 weeks; agents such as ceftriaxone, cefotaxime, and clindamycin are commonly administered and effective in most cases [13–15]. In selected situations, particularly when complications develop, additional interventions may be required. Surgical procedures including pigtail catheter placement, video-assisted thoracoscopic drainage, or lobectomy, are generally indicated when medical therapy fails to achieve clinical improvement or when complications occur (eg, pulmonary sequestration, bronchopleural fistula, or rupture into the pleural cavity with pyopneumothorax) [16–23]. Pulmonary abscesses are commonly classified according to duration, such that acute cases are defined as those lasting less than 6 weeks and chronic cases as those persisting beyond this period. Similarly, indications for surgical intervention are often categorized as acute or chronic. Acute indications include hemoptysis, persistent sepsis, prolonged fever, bronchopleural fistula, or abscess rupture into the pleural cavity with pyopneumothorax or empyema. Chronic indications include lack of response to appropriate therapy for more than 6 weeks, suspicion of malignancy, cavitary lesions exceeding 6 cm in diameter, or persistent leukocytosis despite adequate antimicrobial treatment [16]. In recent decades, interventional and surgical management of pediatric pulmonary abscess has considerably evolved, paralleling advances in imaging and minimally invasive techniques. Percutaneous transthoracic drainage and endoscopic catheter drainage are recognized as safe and effective alternatives [16–23]. These procedures, typically performed under CT or ultrasound guidance, allow both source control and microbiological sampling. They have been associated with improved outcomes, including shorter hospital stays, more rapid recovery, and lower morbidity relative to open surgical approaches [8]. Mortality has been reported with percutaneous transthoracic drainage, whereas endoscopic catheter drainage appears to provide comparable efficacy with fewer associated risks [16–19]. In children, the role of interventional radiology has substantially expanded over the past 2 decades, such that CT-guided aspiration and pigtail catheter drainage are increasingly incorporated into the management of complex cases [8]. These approaches have been associated with higher microbiological yield and reduced length of hospital stay; some series have reported drainage in 11% to 21% of pediatric patients with suboptimal response to medical therapy [5,7,16,17,22]. Nevertheless, most pediatric pulmonary abscesses continue to respond favorably to antimicrobial therapy when treatment is initiated early and guided by close clinical and radiological monitoring. Surgical interventions, including video-assisted thoracoscopic surgery or lobectomy, are generally reserved for refractory disease or anatomically complex lesions [18–23]. The prognosis for children with primary pulmonary abscess remains excellent when management is individualized, with prioritization of optimized medical therapy and incorporation of interventional procedures according to disease severity and clinical progression [16–23]. Pediatric interventional radiology has become an integral component of pediatric hospitals, reflecting its established role in the multidisciplinary management of complex pulmonary infections in children [24]. Treatment strategies are tailored to each patient’s clinical course and response to therapy. Although some centers favor early image-guided drainage to facilitate recovery, others continue to emphasize medical management to reduce procedure-related complications. Current evidence suggests a gradual shift toward earlier interventional approaches, particularly for large or non-resolving abscesses. Further well-designed pediatric studies are required to establish robust evidence-based recommendations and to define the optimal timing and selection of interventional strategies [16–24].

The presence of aerobic organisms may represent a negative prognostic indicator, particularly in patients with secondary pulmonary abscesses. Most children become asymptomatic within 7 to 10 days, although fever may persist for up to 3 weeks. Radiologic abnormalities usually resolve within 1 to 3 months but may persist for years, such as residual B-line artifacts on lung ultrasound. Through the advent of antibiotic therapy and advances in image-guided drainage, mortality associated with pulmonary abscess has substantially decreased over the past century – from historical rates approaching 75% to rates near 20% to 35% following the introduction of open drainage, and currently below 5% among pediatric patients treated with antibiotics and selective interventional procedures [8,16]. Radiological assessment is essential for the diagnosis and monitoring of pulmonary abscesses. In the 2 cases presented, follow-up was based on clinical course and serial plain chest radiographs during hospitalization and outpatient surveillance, which were sufficient to confirm progressive resolution. Ultrasound is increasingly regarded as a valuable follow-up modality for pediatric pulmonary abscesses. When used in monitoring, it allows documentation of lesion resolution, assessment of residual parenchymal changes, and substantial reduction in exposure to ionizing radiation. Despite these advantages, chest CT remains indicated in selected circumstances, including persistent symptoms, atypical clinical progression, or suspected complications; it should be guided by the child’s clinical course and the principle of minimizing unnecessary radiation exposure. In certain settings, magnetic resonance imaging may be considered, depending on clinical course, symptom persistence, and local resource availability [25–27]. This approach balances the need for appropriate radiological follow-up with radiation minimization, highlighting the importance of integrating imaging findings with the patient’s clinical status.

Conclusions

Pulmonary abscess remains an uncommon but clinically significant complication of community-acquired pneumonia in children. Early recognition and accurate etiological identification are critical to guide management and prevent progression to more severe disease. Although both patients achieved complete clinical and radiological recovery with exclusive medical therapy, increasing evidence supports an expanding role for image-guided drainage in selected cases. The expanding availability of pediatric interventional radiology has transformed therapeutic options by providing less invasive and highly effective alternatives to surgery. Therefore, management should remain individualized according to disease severity, clinical course, and institutional resources. A multidisciplinary approach involving pediatrics, interventional radiology, pediatric infectious diseases, and pediatric surgery is essential to optimize outcomes. Further well-designed pediatric studies are required to establish evidence-based recommendations and to define the optimal timing and selection of interventional strategies.