Histoplasma capsulatum, which is the causative agent of histoplasmosis, appears in the soil globally. There are a limited number of histoplasmosis cases reported from Turkey. In this article, we present a patient with Histoplasma pneumonia developed during corticosteroid treatment. A 70-year-old female with invasive ductal carcinoma was admitted to our department with shortness of breath, cough, and weakness. Her clinical and radiological findings were compatible with radiation pneumonitis. Computed tomography of thorax (Thoracic CT) revealed scattered and patchy areas of consolidation, ground-glass opacities, and ground-glass density nodules in all lobes of the lungs. Transthoracic tru-cut biopsy was performed under CT guidance. Histopathological examination showed microorganisms morphologically consistent with Histoplasma became apparent with silver stain in the alveolar lumen. Patient was treated with itraconazole for 6 months. She responded well to the treatment with a complete clinical and radiological regression. Histoplasmosis is a worldwide disease. It should be noted that pulmonary histoplasmosis could be seen in our country. Because of this, pulmonary histoplasmosis should be kept in mind in immunocompromised patients as an opportunistic pulmonary infection in our country