Invasive Fungal Infection Requiring Dif ferential Diagnosis from Miliary Tuberculosis Based on Imaging

Utility of Genetic and Ultrastructural Analyses from FFPE Tissues

Abstract

Invasive fungal infections (IFIs) have increased in recent years due to population aging and a rising number of immunocompromised patients. The prognosis for IFIs remains poor, making accurate diagnosis and appropriate treatment essential. Low culture positivity rates and the difficulty in distinguishing IFIs from diseases such as tuberculosis on computed tomography imaging further complicate diagnosis and may delay. We encountered a case of invasive candidiasis leading to respiratory failure, in which differentiation from miliary tuberculosis on imaging was challenging. Autopsy revealed histopathological findings of eosinophilic exudates filling the alveolar spaces and poorly stained spherical fungi. Using scanning electron microscopy and DNA extraction from formalin-fixed, paraffin-embedded (FFPE) tissues, genetic analysis identified Debaryomyces hansenii, also known as Candida famata. FFPE tissue-based analytical techniques serve as valuable tools for understanding IFIs. If the causative pathogen can be identified during a patient's life, appropriate treatment can be selected, potentially improving the prognosis of IFIs.