대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Legionella pneumophilia pneumonia

Radiologic Findings

Initial and follow-up chest radiograph 3 days later show rapidly progressing peripheral patchy consolidation in both lungs, predomiantly in right lung. Chest CT scans multiple spherical or wedge-shaped consolidations in subpleural portion of right lung. Also noted is small right pleural effusion. Small areas of consolidation were also noted in left lung. Follow-up chest radiographs after treatment showed slow radiographic resolution over two months. Last follow-up radiograph two months later shows residual consolidation in peripheral lung.

Diagnosis of Legionella pneumonphila Pneumonia was established by serum IgM antibody > 1: 512, and urine Ag (+)

Brief Review

Legionnaires’ disease is due to L. pneumophila, an aerobic gram-negative bacillus found in aquatic environments such as reservoirs, colling towers, water distribution systems, and humidifiers. Infection comes from these sources rather than from person-to-person contact.
The infection is characterized by malaise, myalgia, headache, abdominal and chest pain, nausea, vomiting, diarrhea, high fever, rigors, dyspnea, and cough; the cough is usually productive and associated with hemoptysis. Bacterial disseminations causes a variety of extrapulmonary manifestations, including endocarditis, sinusitis, brain abscess, and pancreatitis.

Predisposing chronic diseases include chronic bronchitis, emphysema, malignant diseases, renal failure, and corticosteroid therapy. The organism is difficult to culture from sputum and blood, and selective culture media area required. The diagnosis is usually established serologically by an indirect fluorescent antibody test.
The initial chest radiographic finding is peripherally situated patchy consolidation, which spreads rapidly, often involving more than one lobe and becoming bilateral in half of cases. The consolidation may assume a spherical configuration or may coalesce to resemble lobar pneumonia. Cavitation is unusual; it appears to be most common in immunocompromised patients. Pleural effusions are usually small and are observed in up to two thirds. The radiographic resolution is slow and lags behind the clinical improvement. The changes usually persist for at least a month after the acute illness.

References

1. Armstrong P, Dee P. Infections of the lungs and pleura. In Armstrong P, Wilson AG, Dee P, Hansell DM. Imaging of diseases of the chest. 2nd ed. St. Louis : Mosby, 1995 : 159-160

Keywords

Lung, Infection, Bacterial infection,