Liver involvement is usually feature of disseminated disease
Most common in, but not limited to, immunocompromised patients
Etiology/Pathogenesis
• Worldwide distribution and widespread in nature
• Ubiquitous soil saprophyte; acquired by inhalation
Clinical Issues
• Liver involvement often presents as hepatomegaly, abdominal pain, elevated liver tests
• Helpful laboratory tests include culture, cryptococcal antigen testing, and PCR assays
• Prognosis depends on clinical features of disease, patient’s immune status
Untreated disease is almost always fatal
Microscopic
• Round to oval yeast with narrow-based budding
• Considerable variation in size from 2-20 μm in diameter
• Halo around organisms representing mucopolysaccharide capsule
• Variable inflammatory response
Ranges from suppurative &/or granulomatous inflammation to essentially no tissue reaction in severely immunocompromised patients
• Fungi stain with GMS, Alcian blue, mucicarmine, colloidal iron, and Fontana-Masson
• Capsule deficient organisms are mucicarmine negative or only weakly positive
Fontana-Masson is useful in these cases
Narrow-Based Budding This liver biopsy shows numerous cryptococci expanding the hepatic sinusoids. Note the narrow-based bud and the variation in size. There is minimal inflammatory reaction in this immunocompromised patient.
Mucicarmine Stain Mucicarmine stain highlights the mucopolysaccharide capsule characteristic of Cryptococcus. However, many Cryptococcus strains are capsule deficient, and may be negative for mucicarmine or only weakly positive. (Courtesy B. Smoller, MD.)
GMS Stain Gomori methenamine silver stain highlights the pleomorphic size of Cryptococcus. This slide shows the presence of both small and large organisms.
Fontana-Masson Stain Fontana-Masson will stain the fungi black in Cryptococcus infection, including capsule-deficient fungi, due to the melanin in the cell wall.
TERMINOLOGY
Synonyms
• Cryptococcosis
Definitions
• Infection by fungi Cryptococcus neoformans or Cryptococcus g attii
C. gattii more common in immunocompetent persons
• Most common cause of systemic mycosis in patients with AIDS
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and the variation in size. There is minimal inflammatory reaction in this immunocompromised patient.
