Positive for organisms. Negative for malignant cells. Acute and chronic inflammatory cells and numerous encapsulated fungal yeast forms with some budding, morphologically compatible with cryptococcus sp. No viral inclusions present.
Cryptococcus neoformans has been presumptively identified in the mycology culture.
Cryptococcus neoformans, a saprophytic basidiomycete, is believed to lead to cryptococcosis following inhalation of the organism (1). Most cases occur in immunocompromised patients. Factors predisposing to cryptococcal infection include corticosteroid administration, lymphoreticular malignancies (especially Hodgkin's disease), sarcoidosis and HIV infection; however, 50% of cases have no recognized predisposing condition. Approximately 80-90% of cryptococcosis occurs in AIDs patients (2). The most frequently affected site is the central nervous system, however, the organism has been isolated from almost every organ. Pulmonary cryptococcal infection is often asymptomatic, as was seen in this patient (3). Temperate climates are the primary location for Cryptococcus neoformans var. neoformans (4). The organism is surrounded by a polysaccharide capsule, composed of glucuronoxylomannan, of which there are four serotypes (5, 6). The capsule of the organism inhibits phagocytosis(6).
The radiographic appearance of lung involvement by cryptococcosis may vary depending upon the immune status of the host. Interstitial infiltrates are commonly noted in HIV positive patients (7). However, immunocompromised hosts who are not HIV positive, as in the present case, have been shown to commonly have single or multiple nodules, which may suggest a neoplasm (8). Interestingly, in tissue, cryptococcal organisms produce minimal direct injury. The inflammatory response ranges from none to chronic inflammation with macrophages, lymphocytes, foreign body giant cells/granulomas, and occasionally neutrophils, followed by fibrosis; calcification is uncommon.
The diagnosis of pulmonary cryptococcosis by fine needle aspiration has been previously described (9, 10, 11, 12). The diagnostic yield of fine needle aspiration in theses cases has been shown to be higher than that of bronchoscopy with biopsy (12). Direct cryptococcal antigen determinations on lung aspirates may provide a rapid method to the diagnosis of pulmonary cryptococcosis (13). Direct cryptococcal antigen determinations in serum (12, 14, 15), pleural effusions (16), and bronchoalveolar fluid (17) have also previously been utilized in the diagnosis of pulmonary cryptococcosis.
Contributed by Valerie A. Holst, MD and Sheldon Bastacky, MD