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Fig. 6.56 A-F CT scanning of the chest will often show the changes of paracoccidioidomycosis more clearly. A The chest radiograph and B-D the CT scans of the same patient showing the multiple interstitial, nodular and linear densities. Many of the nodules are rough in outline: thick-walled cavities can be seen. In other areas the infection has coalesced, forming large masses. E, F CT scans of a different patient showing particularly the peribronchial thickening and interstitial fibrosis, with the well-marked emphysematous areas at the lung bases.


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Torulosis. Busse-Buschke's disease. European blastomycosis. Torulosis histolytica. Ger: Cryptococcosis neoformans (Erreger der europäischen Blastomykose). Fr: Cryptocoque neoforme. Sp: Criptococosis neoformans.


A subacute or chronic fungus infection caused by Cryptococcosis neoformans.

Cryptococcosis neoformans occurs in two variants, distinguished by serology: C. neoformans var. neoformans (serotypes A, B, and AD) and C. neoformans var. gattii (serotypes B and C).

Geographic Distribution

C. neoformans var. neoformans is a common pathogen which occurs worldwide: C. neoformans var. gattii only occurs in tropical and subtropical countries: the serotype C infections are limited to southern California.

C. neoformans var neoformans is an opportunistic, saprophytic yeast which is widely distributed, particularly in old pigeon droppings, but also in the droppings or in soil contaminated by droppings from some other birds. It has been cultured from abandoned houses, woods, and soil. C. neoformans var. gattii has been cultured from under the bark and around flowering eucalyptus trees and also in bat droppings. C. neoformans can survive passage through the alimentary tract of birds which are not actually infected themselves. The fungus has also been found on fruit and in milk, e. g., milk from cattle with cryptococcal mastitis.

Infection occurs by inhalation, not by contact: very rarely, fungus may be accidentally inoculated into the skin. Infections by C. neoformans var neoformans occur throughout the year, particularly in cities and towns: infections by C. neoformans var. gatti are more seasonal and more common in rural communities. C. neoformans var. gatti is a little more common in children and young adults whereas C. neoformans var neoformans is more frequent in older (30 to 60-year-old) urban dwellers.

Cryptococcosis has been found in many domestic and wild animals. As will be discussed later, C. neoformans var neoformans is associated with immunosuppression (it is the fourth leading infectious cause of death in patients with AIDS in the United States) and chronic debilitating diseases, while C. neoformans var gatti is found in immunocompetent patients.

The histopathological findings depend on the immune status of the patient. In those who are immunocompetent, pulmonary infections are granulomatous. Yeasts are both extra- and intracellular, and surrounded by a granulomatous reaction including giant cells, epithelioid cells, macrophages, and plasma cells. The extent of necrosis is variable. In more chronic infections, fibrosis develops and residual pulmonary granulomas occur. There is seldem any calcification: these granulomas (cryptococcomas) are usually an incidental finding at autopsy or mistaken for neoplasms on chest radiographs.

In those with deficient immunity, there is minimal if any inflammatory reaction: for example, enormous numbers of yeasts accumulate in the meninges. They have thick mucinous capsules and fill and expand the subarachnoid space. There is no suppuration and no evidence of any granulomatous reaction: it is difficult to detect any host reaction at all. The large number of fungal cells with mucoid capsules are shiny and slimy macroscopically (Fig. 6.61 A). In patients who are severely immunodeficient, the large extracellular aggregates distort the normal architecture of any organ. These masses may be so large that they resemble a tumor, with an irregular outline. In other patients there may be multiple small "miliary" nodules. In patients with progressive pulmonary disease, there will be hilar and mediastinal lymphadenopathy. When necrosis occurs, the larger nodules may show central cavitation, but this does not occur in the miliary pattern. The numerous yeasts in the lung may give the appearance of lobar pneumonia. The diagnosis can be confirmed by finding the organisms in sputum, lung biopsy specimens, and cultures. However, C. neoformans var gattii may be found in the sputum or bronchial washing of normal patients and it does not always mean there is active infection.



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