A 48-year-old woman with a 2-month history of elevated serum CA19-9 levels (50.05 IU/mL, reference range <25IU/mL) without any symptoms was referred to our hospital. The patient was in good health without other chronic diseases before admission. She denied a history of alcohol abuse, drug addiction, and regular medication intake. Notably, her family history showed that her father dies of hepatocellular carcinoma.
On admission to our hospital, no positive findings were noted in the patient after a careful physical examination. The laboratory investigation disclosed the elevated CA19-9 level (46.45 IU/mL, reference range <25 IU/mL), serum alkaline phosphatase level (145 IU/L, reference range 30-120 IU/L), and Limulus test (87 pg/mL, reference range <10 pg/mL). The white blood count, coagulation factors, erythrocyte sedimentation rate, procalcitonin, C-reactive protein carcinoembryonic antigen, alpha fetal protein, and carbohydrate antigen 125 levels were normal. The serology for viral hepatitis (hepatitis B and C) and human immunodeficiency virus was negative. The autoantibodies were also negative, and the serum immunoglobulins were within the normal range.
An abdominal contrast-enhanced magnetic resonance (MR) scan was performed. Multiple abnormal signal nodules were found in the liver. The T2-weighted image (Figure 1A-C) and diffusion-weighted image (DWI, b value = 800 mm/s2) (not shown) showed several hyperintense round-like lesions. The diameter of the largest nodule is approximately 20mm (Figure 1C). Contrast-enhanced MR showed no enhancement of nodules in the arterial phase (see Supplementary Figure 1A-C), while the nodules were slightly hypointense to normal liver parenchyma with peripheral ring-like slight hyperintense area in the portal venous phase (see Supplementary Figure 1D-F) and with peripheral ring-like obvious hyperintense area in the delayed phase (see Supplementary Figure 1G-I). The MR scan suggested that metastatic tumors or infectious diseases should be both considered. 
Contrast-enhanced ultrasound of the liver revealed multiple hypoechoic lesions with blurry margins and a little blood-flow signal, while it depicted the arterial-phase enhancement of lesions, stronger than the surrounding liver (wash-in), and hypoechoic intensity compared to the surrounding liver (wash-out) in the venous phase after intravenous administration of ultrasound contrast agent (SonoVue 2mL). 18-fluorine fluorodeoxyglucose positron emission tomography-computed tomography (18-FDG PET-CT) displayed multiple low-dense lesions of various sizes with obviously increased uptake of nuclear species, which indicated the metastatic liver malignancy could not be excluded. (Figure 1D-F). Although gastrointestinal tumors are the main resources of liver metastasis, no significant signs of malignancy were detected in the gastrointestinal tract after the PET-CT scan. Moreover, no significant lesions were observed after the gastroscopy and colonoscopy examination.
To determine the nature of liver nodules, the patient received a percutaneous liver biopsy guided by ultrasound. The Hematoxylin and Eosin staining of the specimen obtained from the biggest nodule showed granulomatous inflammation with central caseous necrosis and a few multinucleated giant cells (Figure 2A). Masson triple staining indicated that the necrotic area was surrounded by fiber (Figure 2B). The periodic acid-Schiff (PAS), D-PAS, and acid-fast staining (Figure 2C) were all negative. The specimen of para-nodule was presented with chronic inflammatory changes (Figure 2D). No malignant cells were found in the specimens and then the infectious diseases were highly suspected, which need to be further validated. 
The patient denied a history of tuberculosis (TB), diabetes mellitus, or exposure to bird excrement. The chest CT showed no evidence of obvious inflammation. The flow cytometry analysis of T lymphocytes (CD3 cell count 1493 cells/muL, CD4 cell count 830 cells/muL, and CD8 cell count 640 cells/muL) showed that the patient had no apparent immune deficiency. We further conducted infection-related laboratory tests. The T-SPOT.TB, (1,3)-beta-D glucan test, the LFA serum Cr-Ag, and the aspergillus antigen test were all negative. Therefore, the traditional tests did not show any evidence of a specific pathogen. The mNGS of the liver specimen was conducted and the result revealed the identification of the sequence of C. neoformans, but the reads number was 1 and the reads per million ratios were 3.11%, which was the only etiological evidence.
Considering the delay in antifungal therapy related to poorer clinical outcomes, a diagnostic treatment with oral fluconazole (400 mg/day) was administrated after the informed consent of the patient, then follow-up regularly. After 2 months of treatment, the size of the nodules in the liver examined by MR significantly decreased compared to that of baseline, and the diameter of the biggest nodule was approximately 7mm (Figure 1G-I). At the follow-up of 3 months, the dose of fluconazole was subsequently reduced to 200 mg/day due to moderately elevated aminotransferase, and the liver function tests gradually recovered within the next month. After 6 months of treatment, the liver nodules examined by MR almost disappeared (Figure 1J-L), and the serum CA19-9 and Limulus test levels regressed to the normal range.