# P-1720. Histopathological Assessment as a Cornerstone in the Diagnosis of Invasive Fungal Infections: A 10-Year Experience in a Tertiary-Level Hospital in Mexico

## TL;DR

This study shows how histopathological exams are vital for diagnosing invasive fungal infections over a 10-year period in a Mexican hospital.

## Contribution

The study provides a detailed 10-year retrospective analysis of histopathological diagnosis of invasive fungal infections in a Mexican hospital.

## Key findings

- Histoplasma was the most frequent invasive fungal infection, with half of the cases from lung biopsies.
- Pneumocystis was the second most common fungus, predominantly found in lung biopsies of HIV-positive and immunosuppressed patients.
- Histopathological examination was crucial for diagnosing and guiding treatment of fungal infections.

## Abstract

The main objective is to highlight the critical role of histopathological examination in the identification of invasive fungal infections from 10 year samples in our hospital in Mexico City.

A retrospective, descriptive and epidemiological cohort was conducted at Medica Sur Hospital from January 2014 to December 2024. Data regarding comorbidities, particularly immunosuppressive conditions, microbiological findings (culture), serological tests, and whether or not treatment was administered, was collected and analyzed.

We collected a total of 143 samples related to any fungal morphology, however, we excluded yeast from saprophyte tissues and colonizers molds. We included 42 samples that were considered as invasive fungal infections. Histoplasma was the most frequent pathogen (28.6%), 50% of those samples were lung biopsies. Clinically 50% of those patients with Histoplasma were under immunosuppressive therapy. 75% of these patients received antifungal therapy. Pneumocystis was the second most common identified fungus (21.4%), 100% coming from lung biopsies. The baseline diseases that predominated with Pneumocystis pneumonia were patients living with HIV, patients taking immunosuppressive medications and immunocompetent patients, with 44% each. Aspergillus was identified in 17%, with a lung biopsy predominance in 43% of the cases. We had 50% of correlation with positive Aspergillus cultures. Only 29% of these patients received antifungal treatment. Mucor was the fourth most common fungus (12%); 20% of Mucor patients correlated with a positive culture. In 80% of Mucor cases the patients were under immunosuppressive treatment. Cryptococcus (9.5%) was identified most frequently in lung biopsies (50%), and 50% of these patients were immunocompetent. Coccidioides (5%), and Blastomyces (5%) were identified in lung biopsies (100%). Finally, Fusarium represented 2% of the cases, identified in a patient under immunosuppressive medications; the patient received antifungal treatment.

The morphological description of fungal elements in tissue is essential for the diagnosis of invasive fungal infections, which guides decision-making in the clinical setting for an adequate treatment.

All Authors: No reported disclosures