Infect > Fungus > Crypto



There are two predominant species that cause infection in humans- C. neoformans (infecting predominantly immunocompromised individuals) and C. gatti (which is endemic in the Northwest US and can infect both healthy and immunocompromised individuals) [7]. Birds (esp. pigeons) are reservoirs for the organism (a budding encapsulated yeast) which can be seen on stain with india ink. The organism is particularly abundant in soil contaminated by pigeon droppings. Most patients who develop cryptococcus are immune compromised or immunosuppressed- particularly HIV and Hodgkin's patients, but also patients using oral corticosteroids.

Cryptococcus is the most common fungal pneumonia in HIV patients [1,3]. Most patients have severe immune compromise with CD4 counts below 100 cells/ul. Cryptococcal pneumonia is usually associated with disseminated disease and occurs in 30-45% of AIDS patients with cryptococcal infection [2,3]. The CNS is the most common site of disseminated infection- where the infection typically produces a lethal meningitis. A concomitant meningitis is found in up to 86% of cases, although it commonly clinically silent. In HIV patients that present with CNS cryptococcal infection, clinically silent pulmonary disease can be found in just over 25% of cases.

In patients with normal immunity, infection is usually asymptomatic (one-third of patients) [5,7], although cough has been described in up to 69% of patients [6]. Fever is uncommon (up to 8% of patients) [6]. The most common radiographic finding is the presence of multiple peripheral pulmonary nodules (less than 10 mm in size [7-20mm]) which rarely calcify. The nodules typically have well defined margins, although irregular or poorly defined margins can also be seen [4,6]. Areas of air space consolidation are the next most common finding and can be seen with or without associated nodules [6]. Masses, lymphadenopathy, and pleural effusion occur infrequently in immunocompetent patients [4,5]. Cavitation of the nodules (or airspace consolidation) is variable and has been reported as infrequent [4,7] to up to 40% of cases on CT [5]. Cavitation is more commonly seen in immunocommpromised patients [6].
Immune compromised patients present with cough (94%), fever (50%), chest pain (44%), shortness of breath (38%), and headache (31%) [6]. In immunocompromised patients, some authors feel that segmental or lobar consolidation is a common manifestation of cryptococcal pulmonary infection [1]. Other authors feel that interstitial infiltrates, primarily reticular or reticulonodular, are the most common radiographic pattern (50-62% of cases) [2]. Pulmonary nodules are also common and found in up to 30-40% of cases [1,2] and there is a propensity for the nodules to cavitate [1]. Nodules may be more common in patients with early HIV infection [2]. A cavitary nodule in an HIV patient is very suggestive of either PCP or cryptococcal infection [1]. Hilar and mediastinal adenopathy can also be seen, as can pleural effusion (up to 10% of patients [6]) [1,2]. Occasionally, patients may develop a rapidly progressive fulminant infection resulting in an ARDS type picture [1]. Disseminated disease typically produces a miliary pattern on the chest radiograph [1], although some feel that this is an atypical presentation for pulmonary cryptococcal infection in the HIV patient [2].

(1) Semin Roentgenology 1996; Woodring JH, et al. Pulmonary cryptococcosis. 31 (1): 67-75 (Review. No abstract available.)

(2) Radiologic Clinics of North America 1997; McGuinness G. Changing trends in the pulmonary manifestations of AIDS. 35 (5): 1029-1082

(3) J Thorac Imaging 1999; Connolly JE, et al. Opportunistic fungal pneumonia. 14: 51-62

(4) Radiology 2005; Lindell RM, et al. Pulmonary cryptococcosis: CT findings in immunocompetent patients. 236: 326-331

(5) AJR 2005; Fox DL, Muller NL. Pulmonary cryptococcosis in immunocompetent patients: CT findings in 12 patients. 185: 622-626

(6) Chest 2006; Chang WC, et al. Pulmonary cryptococcosis. Comparison of the clinical and radiographic characteristics in immunocompetent and immunocompromised patients. 129: 333-340

(7) Radiographics 2021; Kunin JR, et al. Thoracic endemic fungi in the United States: importance of patient location. 41: 380-398

Latest in Infections-Inflammatory
More in Infections-Inflammatory
Page 1 of 18
Next Page