Pulmonary abscess is a rare but serious condition in pediatric patients, caused by severe pulmonary infection that leads to tissue destruction and necrosis. It can be classified as primary or secondary depending on the cause. Establishing an etiology in pediatric pulmonary abscesses is challenging, underscoring the essential role of advanced imaging techniques, such as computed tomography, in achieving an accurate diagnosis and differentiating among various conditions that may mimic lung abscess. While conservative management with antibiotics is the first line of treatment, some cases may progress and require surgical intervention. We present two clinical cases of pediatric lung abscesses, emphasizing the importance of timely intervention, accompanied by a brief review of current knowledge that highlights key clinical features, diagnostic challenges, and therapeutic approaches in pediatric lung abscess.

Lung abscess found on chest X-ray and computed tomography examinations is rare in infants and young children. Several pathogens can cause lung abscesses, with the most common pathogens being anaerobes, Streptococci and Staphylococcus aureus. Streptococcus pseudopneumoniae (S. pseudopneumoniae) is a member of the Streptococcaceae family, and is mainly isolated from respiratory tract specimens. There are currently no cases of lung abscess caused by S. pseudopneumoniae in the literature.

A 2-year-old boy was admitted to hospital due to persistent cough and fever. Lung computed tomography examination suggested the formation of a lung abscess. His diagnosis was not confirmed by testing for serum respiratory pathogens (6 items), respiratory pathogen nucleic acid (27 items), and laboratory culture. Finally, metagenomic next-generation sequencing of bronchoalveolar lavage fluid revealed the presence of S. pseudopneumoniae, confirming its role in causing the lung abscess. After receiving antibiotic treatment, reexamination with lung computed tomography showed that the abscess was resorbed and the patient's outcome was good.

This is the first report of a lung abscess in a child caused by S. pseudopneumoniae infection. Metagenomic next-generation sequencing of bronchoalveolar lavage fluid is helpful in achieving rapid and accurate pathogen identification.

Intrathoracic extraskeletal Ewing's sarcoma (EES) is a relatively uncommon malignant tumour. Here, we present a scenario involving an adult man in his 20s with a large intrathoracic EES that manifested as a lung abscess. Preoperative diagnostic tests were inconclusive; hence, the patient underwent an exploratory thoracotomy for the excision of the mass. Histopathology revealed a small round blue cell tumour, and immunohistochemistry, along with fluorescence in situ hybridisation, confirmed the diagnosis of Ewing's sarcoma. Adjuvant chemoradiotherapy was recommended, but the patient did not comply. A year later, he presented with a recurrence of the intrathoracic mass and subsequently received adjuvant chemotherapy. Currently, he is in remission.