Invasive pulmonary cryptococcosis mimicking metastatic lung cancer: A case report and review of literature.

BACKGROUND: Worldwide, there has been a steady increase in the number of cases of pulmonary cryptococcosis diagnosed in immunocompetent patients, where symptoms can range from mild to severe. Clinical and radiological distinction of disease may be made when compared with immunodeficient cases and in those presenting with primary lung carcinoma. In the latter case confusion can lead to initial misdiagnosis and delayed treatment. We report a case of disseminated cryptococcosis in an immunocompetent patient which mimicked a primary lung carcinoma with brain metastases.

CASE SUMMARY: A 51-year-old male farmer with a 30-year smoking history presented with a two-week history of productive cough, streaky hemoptysis, and low-grade fever. He had no history of immunosuppression, tuberculosis, or specific risk factors. Chest computed tomography revealed a posterior basal left lower lobe mass, but tumor markers and transbronchial tests were negative. Brain magnetic resonance imaging showed an enhancing left frontal lobe lesion, raising suspicion for metastatic lung cancer. However, computed tomography-guided biopsy confirmed fungal pneumonia with "titan" cells, and a positive serum cryptococcal antigen test confirmed Cryptococcus neoformans infection. Bronchoscopy and lavage detected fungal spores, while cerebrospinal fluid cytology and culture were negative. Fluconazole (0.4 mg/day) was initiated, but progressive central nervous system lesions required amphotericin B. A six-week combination of fluconazole (600 mg/day) and flucytosine led to resolution. At 24-month follow-up, he remained asymptomatic with no recurrence.

CONCLUSION: Cryptococcosis is increasing in immunocompetent individuals in China and should be considered in pneumonia and lung or brain lesions.