대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Cryptococcosis, disseminated form, in immunocompetent individual

Radiologic Findings

Chest CT scan shows multiple necrotic lymph nodes in the mediastinum and hila, multiple well-defined small nodules in both lungs, predominantly in peripheral lung, and small bilateral pleural effusion (not shown). Abdomen CT scan shows multiple small low-density nodular lesions in the liver and spleen, multiple necrotic abdominal lymph nodes and small amount of ascites.

Cervical lymph node biopsy specimen shows noncaseating granulomatous reaction. Yeast-like organisms with thick capsule in multinucleated giant cells (PAS stain).

Brief Review

Cryptococcus neoformans is an ubiquitous yeast with a worldwide distribution and its natural habitat is the soil, especially that containing pigeon or other avian excreta.

Cryptococcosis is caused by inhalation of spores of Cryptococcus neoformans. Principal sites of disease include lungs, CNS, blood, skin, bone, joints and prostate.Approximately one third of patients are asymptomatic, whereas the rest symptoms range from mild cough and low-grade fever to an acute, febrile, life-threatening illness. Approximately one half to two thirds of the cases of symptomatic infection are associated with immunodeficiency.Cryptococcosis is a major fungal disease in patients with AIDS, usually presenting as meningitis, pulmonary infiltrates, or both. Other risk factors for cryptococcosis include treated malignancies, organ transplantation with immunosupression, collagen vascular disease (especially with corticosteroid therapy), and chronic heart failure. Immunocompromised patients differ from immunocompetent individuals both in the tissue response to the organism and in the course of the disease. The disease can spread rapidly throughout the lungs and disseminate to extrapulmonary sites, especially the meninges in immunocompromised patients. In contrast, it is more usual in immunocompetent hosts for the infection to be localized to one area of the lung. Histopathologic features are different between immunocompetent and immunocompromised patients. In immunocompetent patients, granulomatous response occurs. The response may consist of numerous noncaseating granulomas, or there may be extensive caseation. Yeasts can be found both within the necrotic centers of granulomas and within multinucleated histiocytes. In immunocompromised patients, little, if any, inflammatory reaction occurs. Instead, intact alveolar spaces become filled with the yeasts. Vascular invasion, especially of capillaries, may be prominent. McDonnell et al. reported that organisms were present in alveolar capillaries in 27 % of the patient group with chronic debilitating disease.

Radiographically, single or multiple nodular densities are the most common findings. Cavitation occurs in 10-15% of cases. Segmental consolidation and miliary pattern are seen less commonly. Hilar and mediastinal adenopathy may accompany any of these patterns, as may pleural effusion. Cryptococcal pneumonia in AIDS patients shows somewhat different features from those described in non immunocompromised patients in that nodular masses are uncommon and lymphadenopathy is a frequent findings.

Diagnosis can be established based on identification of the characteristic yeast-like organism with capsule in tissue with India ink, silver or mucicarmine stain. Diagnosis of pulmonary cryptococcosis can be established by transbronchial or transthoracic biopsy. In AIDS patients, BAL often will demonstrate organisms cytologically or by culture.

Most patients with pulmonary cryptococcosis do not need treatment. But amphotericin B, flucytosine has required in disseminated disease.

References

1. Patz EF, Goodman PC. Pulmonary cryptococcosis. J Thorac Imaging 1992;7:51-55
2. Khoury MB, Godwin JD, Ravin CE, et al. Thoracic cryptococcosis: Immunologic competence and radiographic appearance. AJR 1984; 141:893-896
3. Miller WT Jr, Edelman JM, Miller WT. Cryptococcal pulmonary infection in patients with AIDS: radiographic appearance. Radiology 1990; 175:725-728
4. Sobonya RE. Fungal diseases, including allergic bronchopulmonary aspergillosis. In Thurlbeck WM, Churg AM. Pathology of the lung. 2nd ed. New York:Thieme. 1995: 317-320
5. McDonnell JM, Hutchins GM. Pulmonary cryptococcosis. Hum Pathol 1985: 16;121-128

Keywords

Lung, Infection, Fungal infection,