Round Pneumonia

Authors:
Alexander Wetzig, BS; Katrina Barnes, BS; and Anand Gourishankar, MBBS, MRCP
McGovern Medical School at UTHealth, Houston, Texas

Citation:
Wetzig A, Barnes K, Gourishankar A. Round pneumonia. Consultant. 2018;58(11):320-321.

A 2-year-old boy presented to the emergency department (ED) with a persistent cough with production of green purulent sputum.

History. The patient’s medical history was significant for a febrile seizure and repair of mixed total anomalous pulmonary venous return with stenting of left and pulmonary vein confluences, as well as respiratory syncytial virus bronchiolitis 1 month before admission. His primary care physician had prescribed 5 days of prednisolone out of concern for a cough that likely was a symptom of reactive airway disease. On the final day of corticosteroid therapy, the patient’s mother had noticed that the boy suddenly had developed difficulty breathing and felt feverish.

Physical examination. In the ED, the patient’s vital signs were as follows: temperature, 38°C; blood pressure, 98/57 mm Hg; heart rate, 147 beats/min; respiratory rate, 31 breaths/minute; and oxygen saturation, 94% on room air. Pertinent physical examination findings were abdominal breathing and mild subcostal retraction. He was treated with a bronchodilator (albuterol-ipratropium combination) and 8 L/min of oxygen via a nasal cannula, in addition to 20 mL/kg normal saline bolus.

Findings of a subsequent physical examination included respiratory distress with tachypnea, subcostal and intercostal retractions with nasal flaring, and grunting, as well as symmetric coarse breath sounds. Cardiovascular examination findings were unremarkable.

Diagnostic tests. A chest radiograph (Figure 1) demonstrated a single well-circumscribed opacity within the left upper lobe, and he received intravenous vancomycin and cefepime. Blood cultures eventually grew Streptococcus pneumoniae.

The following day, the patient was weaned from oxygen therapy and was stable on room air. The patient demonstrated excellent ability to tolerate an oral diet, and he was discharged to home to complete a total of 10 days of antibiotic (amoxicillin) therapy. A follow-up chest radiograph after 4 months (Figure 2) showed resolution of pneumonia.

NEXT: Discussion

Discussion. Round pneumonia is a common clinical entity in children and adolescents. Studies show that the mean age at diagnosis ranges from 3.3 to 5 years, with a nearly equal sex ratio.^1,2 When combined with the correct clinical picture of pneumonia, it is a relatively benign radiologic finding. However, the presence of round pneumonia warrants consideration, because a solitary spherical pulmonary mass, regardless of the patient’s age, is particularly concerning for more-serious inflammatory masses such as hilar lymphadenitis, congenital anomalies, and neoplasms that can mimic the condition.²

The unique histology of the pediatric lung may explain why round pneumonia occurs more often in children. Compared with adults, children have poorly developed pathways of collateral ventilation, more closely apposed connective tissue septa, and smaller alveoli. They have yet to form the intra-alveolar communicative channels (pores of Kohn and canals of Lambert). In an adult, these channels allow for lateral dissemination of the infection throughout the lobe. Thus, in a child host, the infiltrative process of bacterial pneumonia is more compact and without communication, represented by a sharply circumscribed spherical mass on chest radiographs.^1-3

Patients with round pneumonia typically present with mild symptoms that may mimic a viral infection or bronchitis.⁴ They will likely have a history of a cough, tachypnea, and generalized malaise, followed by acute febrile illness.² Although the clinical presentation may lead to suspicion of round pneumonia, the diagnosis ultimately is made with evidence seen on chest radiographs or computed tomography (CT) scans.

In a case review of 109 pediatric patients with round pneumonia diagnosed via 1 of these 2 imaging modalities, 98% of cases were solitary lesions; 70% of these lesions had well-defined borders.¹ In order of most frequent to least frequent, 36 of the 109 patients had lesions in the left lower lobe, 33 in the right lower lobe, 28 in the right upper lobe, 7 in the left upper lobe, 4 in the right middle lobe, and 2 in the lingula. The posterior region of the lung lobe is the location of 83% of round pneumonia cases.¹ Imaging findings with these characteristics lead clinicians to a diagnosis of round pneumonia.

Plain radiographs, which have high specificity and high sensitivity for round pneumonia, are used in most cases. CT is reserved for patients who do not present with a classic clinical picture of pneumonia, who do not have a resolution of a round opacity after a course of antibiotic treatment, or who have evidence of lesions elsewhere and suspicion for metastatic disease.⁴

Treatment of round pneumonia, like other pneumonia types, should be directed at the causative organism (viral, bacterial, or atypical bacterial). Repeated radiographic studies in the pediatric population with round pneumonia after appropriate antibiotic therapy have been shown to be of little value in patients whose clinical symptoms are responding well to treatment.⁵

References:

1. Kim Y-W, Donnelly LF. Round pneumonia: imaging findings in a large series of children. Pediatr Radiol. 2007;37(12):1235-1240.
2. Restrepo R, Palani R, Matapathi UM, Wu Y-Y. Imaging of round pneumonia and mimics in children. Pediatr Radiol. 2010;40(12):1931-1940.
3. McLennan MK. Radiology rounds. Round pneumonia. Can Fam Physician. 1998;44:751-759.
4. Wagner AL, Szabunio M, Hazlett KS, Wagner SG. Radiologic manifestations of round pneumonia in adults. AJR Am J Roentgenol. 1998;170(3):723-726.
5. McCrossan P, McNaughten B, Shields M, Thompson A. Is follow up chest X-ray required in children with round pneumonia? Arch Dis Child. 2017;​102(12):1182-1183.