대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Varicella-Zoster pneumonia

Radiologic Findings

Initial chest radiograph shows some small nodules in right upper lobe. Hilar lymphadenopathy is suspected. Two days later, there are seen about 3-5 mm size poorly defined nodules with confluence in whole lungs and ground glass attenuation with air space consolidation in both middle and lower lungs.

HRCT scan reveals about 2-5 mm size nodules in both lungs with well-defined margin or with peripheral ground glass attenuation halo. There are lobular pattern of ground glass attenuation, small consolidations, and thickening of interlobular septa, which are predominant in both middle and lower lungs. Small amount of bilateral pleural effusion is noted and both hilar lymphadenopathy are suspected.

Brief Review

Herpes varicellae (varicella-zoster virus) infection is seen in two clinical forms: chickenpox (varicella), representing primary disease in previously uninfected individuals, and zoster (singles), usually considered to represent reactivation of latent virus. The overall incidence of pneumonia in patient with chickenpox appears to be about 15%, but in adults admitted to the hospital it may be as high as 50%. About 90% of affected patients are aged 20 years or older, a relatively high incidence of pneumonia in sharp contrast with the low incidence of varicella itself in this age group-50% of cases occur in children younger than 6 years of age, and only 20% occur in adults. Pre-existing neoplastic disease, particularly leukemia and lymphoma, and corticosteroid and broad-spectrum antibiotic therapy predispose to pneumonia. In addition, pregnancy, heavy smoking, old age, chronic obstructive pulmonary disease, and severe cutaneous rash are also documented as risk factors.

In most cases of chickenpox, there is a history of contact with an infected child 3 to 21 days before the development of disease. The onset often is marked by high fever, which may precede the rash by 2 to 3 days. Symptoms and signs of pneumonia develop a few days after the rash appears. When pneumonia develops, the rash tends to be unusually severe and often extends onto the mucosa of the mouth and pharynx.

Histologic features of pneumonitis in chickenpox and zoster are similar and consist of an interstitial mononuclear inflammatory infiltrate, associated with intra-alveolar proteineous exudates, hyaline membrane formation, and type 2 cell hyperplasia (diffuse alveolar damage). Pathologic features of remote chickenpox infection consist of spherical nodules scattered randomly throughout the lung parenchyma. Histologically, they are composed of an outer, often lamellated fibrous capsule frequently enclosing areas of hyalinized collagen or necrotic tissue.

The characteristic radiographic pattern of acute varicella pneumonia is multiple 5- to 10-mm ill-defined nodules or small consolidations that may be confluent and may come and go in different areas of the lungs. Hilar adenopathy and small pleural effusions may occur during the acute phase of the disease but are unusual. The small, round consolidations usually resolve within a week after the disappearance of the skin lesions, but they can persist for months. In milder cases, the infiltrates may resolve in 3-5 days. However, in widespread severe disease, the radiographic abnormalities may persist for several weeks. An unusual manifestation of chickenpox pneumonia consists of tiny widespread foci of calcification throughout both lungs in persons who had the disease many years before in adulthood. The calcifications vary in size and number but seldom exceed 2-3 mm in diameter; they predominate in the lower half of the lungs. Reported HRCT findings of chickenpox pneumonia are small 5- to 10-mm ill-defined nodules, nodules with surrounding ground glass attenuation, patchy ground glass attenuation, and coalescence of lesions.

References

1. Fraser RG, Freaser RS, Pare JAP, Pare PD, Generics GP. Diagnosis of diseases of the chest, 4th ed. Philadelphia Saunders, 1999;2507-2508

2. Kim JS, Ryu CW, Lee SI, Sung DW, Park CK. High-resolution CT findings of varicella-zoster pneumonia. AJR 1999;172:113-116

Keywords

Lung, Infection, Viral infection,