Pulmonary cryptococcosis showing a solitary nodule in patients with previous malignancy.

Pulmonary cryptococcosis is one of the pulmonary fungal infections caused by the inhalation of Cryptococcus neoformans. Pulmonary cryptococcosis shows various radiological findings and sometimes a pulmonary nodule on CT. We experienced three cases of pulmonary cryptococcosis showing a solitary nodule in patients with previous malignancy. All three cases show a newly emerging or growing nodule. Two cases whom FDG-PET was tested showed accumulation of FDG. All three cases underwent pulmonary resection and were pathologically diagnosed with pulmonary cryptococcosis. It is difficult to distinguish a pulmonary nodule due to cryptococcosis from pulmonary malignancy such as a primary lung cancer and a pulmonary metastasis. Especially, it is important to distinguish a pulmonary metastasis from a nodule due to infection in patients with previous malignancy. Surgical resection for diagnosis is often necessary for such cases.