Pulmonary cryptococcosis mimicking lung cancer with multiple lung metastases

Abstract

Key message

The differential diagnosis of a lung mass with multiple pulmonary nodules includes metastases of lung cancer, mycobacterial infections, and pulmonary mycosis. Pulmonary cryptococcosis should be recognized, especially in immunocompromised patients.

CLINICAL IMAGE

A 70-year-old woman was referred to our hospital for evaluation of abnormal lung shadows. She has been treated for polyarteritis nodosa with prednisolone 12.5 mg/day and azathioprine 100 mg/day for 8 years. Chest computed tomography (CT) revealed a left upper lung mass (Figure 1, yellow arrowhead) adjacent to the aortic arch and multiple lung nodules in other lobes (Figure 1, red arrows) (Figure 2, three-dimensional image). Blood tests showed an increased concentration of carcinoembryonic antigen (8.0 ng/mL), but no elevated levels of cytokeratin 19 fragments, progastrin-releasing peptide, C-reactive protein, or β-D-glucan. A transbronchial biopsy specimen obtained from a mass in the left upper lobe revealed many round yeast cells (Figure 3, red arrows). Cryptococcus neoformans was detected in a culture of bronchial lavage fluid. Peripheral blood glucuronoxylomannan antigen was positive. The patient's illness was diagnosed as pulmonary cryptococcosis. She was treated with 400 mg fluconazole once daily and 6000 mg 5-fluorocytosine 4 times daily, which reduced the size of lung lesions. Cryptococcosis presents as a solitary nodule or as multiple pulmonary nodules.¹ More than 40% of patients with histopathologically diagnosed pulmonary cryptococcosis were initially misdiagnosed.² Pulmonary cryptococcosis may mimic lung cancer with multiple lung metastases or tuberculosis.

FIGURE 1. Axial (A), sagittal (B), and coronal (C) views of contrast-enhanced computed tomography images of the chest show an irregular mass (yellow arrowhead) adjacent to the aortic arch. Axial (D) views of chest CT images show multiple lung nodules (red arrows) connecting to the pulmonary arteries without the bronchus sign in the right middle and lower lung lobes.

FIGURE 2. Three-dimensional image of the primary mass lesion (yellow) in the left upper lobe and multiple lung nodules (yellow) in the other lobes. The image was created by a three-dimensional computed-tomography image-analysis system (SYNAPSE VINCENT; FUJIFILM, Japan). The yellowish, bluish, greenish, reddish, and purplish-coloured regions indicate the right upper, middle, right lower, left upper, and left lower lobes, respectively. The tracheobronchial tree is shown in light blue.

FIGURE 3. Histological examination of a transbronchial biopsy specimen obtained from a mass in the left upper lobe reveals many round yeast cells staining positive with Grocott's stain, which is compatible with cryptococcosis. (A) Haematoxylin–eosin, (B) periodic acid-Schiff, and (C) Grocott's staining (original magnification ×200). Red arrows indicate typical examples of round yeast cells.

AUTHOR CONTRIBUTIONS

HO, TH, HN, and AY cared for the patient. HO performed the bronchoscopy procedure and created three-dimensional image of chest CT. All authors contributed to the writing and approved the final version of the manuscript. The images have not been previously published.

CONFLICT OF INTEREST STATEMENT

None declared.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

ETHICS STATEMENT

The authors declare that appropriate written informed consent was obtained for the publication of this manuscript and accompanying images.