Common Variable Immunodeficiency and Peripheral Lung Nodule

Cryptococcus neoformans is an encapsulated yeast first isolated by Busse in 1894 from the tibia of a 31-year-old woman [1]. Lungs are considered the initial site of almost all cryptoccocal infections, and the second clinically more relevant after central nervous system. The pattern of pulmonary disease is extremely variable, ranging from asymptomatic saprophytic airway colonization to acute respiratory distress syndrome, mainly observed in immunocompromised patients [2]. Exposition to Cryptococcus is virtually universal, and usually occurs during childhood. It is thought that humans become infected after inhalation of the fungus. Afterwards, it causes a little focal pneumonitis which may or may not becomes symptomatic, mainly depending on the immune status of the host. In this initial phase of infection, animal models have demonstrated that alveolar macrophages, natural killer cells and helper T-cells are the most important host defence mechanisms against the fungus. In fact, the most serious infections usually occur in subjects with conditions associated with defective cell-mediated immunity, such as acquired immunodeficiency syndrome (AIDS), cirrhosis, renal failure, sarcoidosis, chronic lung disease, diabetes, stem-cell and solid organ transplantation, malignancies, and treatment with long-term corticosteroids of tumour necrosis factor (TNF) antagonists. However, patients with immunoglobulin deficiency are less prone to develop this fungal infection [3].