A case of pulmonary cryptococcosis by capsule-deficient Cryptococcus neoformans.

Pulmonary infection by capsule-deficient Cryptococcus neoformans (CDCN) is a very rare form of pneumonia and it is seldom seen in the immunocompetent host. The authors experienced a case of pulmonary cryptococcosis by CDCN in 25-year-old woman who was without any significant underlying disease. The diagnosis was made from the percutaneous lung biopsy and special tissue staining, including Fontana-Masson silver (FMS) staining. Fungal culture confirmed the diagnosis afterward. Her clinical and radiologic features improved under treatment with fluconazol. It's known that CDCN is not so readily confirmed because fungal culture does not always result in growth of the organism and the empirical fungal stain is not helpful for the differentiation between CDCN and the other infections that are caused by the nonencapsulated yeast-like organisms. In this report, we emphasize the diagnostic value of performing FMS staining for differentiating a CDCN infection from the other confusing nonencapsulated yeast-like organisms.