Anastrozole-induced pulmonary cryptococcosis in a patient with early breast cancer: A case report

INTRODUCTION: Estrogen is a key factor in breast cancer carcinogenesis, and reductions in its synthesis can decrease breast cancer risk. Anastrozole can reduce plasma estrogen levels by inhibiting the enzyme aromatase, and is approved for adjuvant treatment of breast cancer. We report a case of pulmonary cryptococcosis in a patient who was treated with anastrozole for an early-stage tumor. This case is of special interest because the patient achieved a better curative effect after the administration of anastrozole was discontinued. PATIENT CONCERNS: A 61-year-old woman was found to have multiple pulmonary nodules on chest computed tomography (CT) after being treated for 5 months with anastrozole as an adjuvant breast cancer therapy. A biopsy of the largest lesion of the right lung showed cryptococcus fungal bodies with granulomatous inflammation, so the patient was diagnosed with pulmonary cryptococcosis. She was treated with fluconazole (400 mg/day) for 1 month, but a follow-up CT scan of chest showed no improvement. DIAGNOSIS: Pulmonary cryptococcosis. INTERVENTIONS: Because the pulmonary cryptococcosis was not improving, the administration of anastrozole was discontinued. Fluconazole was continued. OUTCOMES: The pulmonary lesions diminished in size 2 months after discontinuing anastrozole. The patient continued taking fluconazole for a total of 6 months without re-administration of anastrozole, and the lesions of pulmonary cryptococcosis almost disappeared. CONCLUSION: This case of pulmonary cryptococcosis may have been induced by a decrease in estrogen level caused by the aromatase inhibitor, anastrozole. Treatment of pulmonary cryptococcosis with concurrent anastrozole use may be ineffective, and it may be better to discontinue the aromatase inhibitor.