Imaging of round pneumonia and mimics in children

Abstract

Various diseases in the pediatric age group can present as an intrathoracic rounded opacity on a chest radiograph. The purpose of this pictorial essay is to emphasize the imaging appearance of round pneumonia, an entity that occurs especially in the pediatric population. Additional pathologies with similar chest radiographic appearances are also presented. The diagnosis of round pneumonia should be made in children who have the typical clinical presentation along with chest radiographs demonstrating the characteristic findings.

Pediatric Round Pneumonia

“…2 Young children are predisposed to round pneumonia because of their underdeveloped pores of Kohn and Lambert's channels that may cause the centrifugal spread of fluid or bacteria. 3 In a recent large study involving 109 children with round pneumonia, the consolidations tended to be solitary, have well-defined borders, and were located posteriorly and in bilateral lower lobes (63%), 4 which exactly matched the initial radiographic findings in our patient (Figure 1). Although the exact term "round pneumonia" does not seem to be widely used by pediatricians in Taiwan, a previous study identified typical imaging features in 5% (2/39) of children with mycoplasmal pneumonia, whose lesions had been described as "nodular or mass-like opacification".…”

“…Their clinical and radiographic characteristics have been thoroughly reviewed. 3,14 The normal results of lactate dehydrogenase, uric acid, liver function tests, and peripheral blood smear in our patient suggested a very low likelihood of malignancy. Meanwhile, the patient's good clinical condition permitted a therapeutic trial with oral antibiotics.…”

“…6 With the typical clinical presentation and radiographic appearance, misdiagnosis of round pneumonia is unlikely, and unwarranted additional imaging should be avoided. 3 Computerized tomography (CT) of the chest is recommended when (1) the clinical features are not consistent with pneumonia, (2) the round opacity does not resolve after appropriate antibiotic treatment, or (3) there are radiographic signs of a nonpulmonary origin on CXR. 3 Round pneumonia is most commonly caused by S. pneumoniae 3 and may rarely be caused by other bacteria, 4 while viral etiology such as severe acute respiratory syndrome has also been seen in adults.…”

“…3 Computerized tomography (CT) of the chest is recommended when (1) the clinical features are not consistent with pneumonia, (2) the round opacity does not resolve after appropriate antibiotic treatment, or (3) there are radiographic signs of a nonpulmonary origin on CXR. 3 Round pneumonia is most commonly caused by S. pneumoniae 3 and may rarely be caused by other bacteria, 4 while viral etiology such as severe acute respiratory syndrome has also been seen in adults. 7 In our patient, although the initial blood culture was negative, results of a urinary antigen test revealed the presence of S. pneumoniae.…”

Single pulmonary round mass in a 12-year-old boy

“…A repeat CXRay 2 months later showed areas of persistent stellate atelectasias (figure 2). Round pneumonia, a rounded region of consolidative parenchymal pulmonary infection, is a rare, benign pulmonary infection in children and is usually caused by Streptococcus pneumoniae 1. It particularly occurs in individuals younger than 8 years of age because of underdeveloped pathways of collateral ventilation (pores of Kohn, channels of Lambert), more closely apposed connective tissue septae, smaller alveoli than adolescents and adults, thus limiting the spread of the organism and resulting in a focal round mass seen on radiographs and CTs.…”