Case of Pulmonary Cryptococcosis Mimicking Hematogeneous Metastases in an Immuocompetent Patient: Value of Absent 18F-Fluorodeoxylucose Uptake on Positron Emission Tomography/CT Scan
A 49-year-old man was admitted with a complaint of dry cough over the last two weeks, and pulmonary nodules were incidentally found on his chest radiography () at our outpatient department. Due to the pulmonary nodules of unknown cause, CT of the chest was arranged. Multiple well-defined nodules (number: more than 10) were observed in both lungs (). Each nodule differed in size, ranging from 4 mm to 12 mm; moreover, the nodules were randomly distributed in every lobe, accompanied by minimal pleural effusions.\nThe patient denied being easily fatigued or having night sweats or rapid weight loss. No recent travel history was noted. The physical examination and all the laboratory tests presented no remarkable findings. We initially considered the nodules to have arisen from hematogeneous metastases. However, tumor markers, such as carcinoembryonic antigen, squamous cell carcinoma antigen, and prostate-specific antigen were all detected to be in the normal range. The gastroscopy and colonoscopy also showed within normal findings. After failing to find any possible primary malignancy, we arranged a whole body 18F-fluorodeoxyglucose (FDG) PET scan to evaluate the possible primary malignancy. The whole body FDG PET scan revealed no abnormal FDG uptake (). Our preoperative diagnosis of hematogeneous lung metastases was based on the presence of multiple pulmonary nodules of varying sizes, which distributed randomly throughout the lung; however, the findings of the whole-body FDG PET scan indicated that the nodules were possibly benign.\nTwo nodules each from the right middle and lower lobe were surgically removed; Histopathology revealed a fibrotic nodule with mild peripheral granulomatous inflammation and many cryptococcal spores () within the central necrotic area (). No evidence of malignancy was noted.\nAfter diagnosing pulmonary cryptococcosis, a series of examinations were performed for greater detail, such as immunoglobulin levels, HIV by enzyme-linked immunosorbent assay, serum and cerebrospinal fluid cryptococcal antigens, but tested negative. The patient was then administered intravenous fluconazole, shifting to oral drugs 400 mg per day, for three months, after discharge. The nodules remain stable in size and number, during a one year follow up.