Disseminated paracoccidioidomycosis in a black lion tamarin (Leontopithecus chrysopygus) confirmed by histopathology, molecular diagnostics and phylogenetic analysis of DNA from FFPE tissues

Background Paracoccidioidomycosis (PCM) is a systemic mycosis endemic to Latin America, primarily affecting humans. Reports in non-human primates are rare and provide valuable insight into the environmental circulation of Paracoccidioides spp. and the interface between animal and human infection. Case report We describe a case of disseminated PCM in a 13-year-old black lion tamarin ( Leontopithecus chrysopygus ) from São Paulo, Brazil. The animal presented neurological signs and marked clinical deterioration, progressing to death within 48 h of the onset of neurological signs. Histopathological analysis of multiple organs revealed granulomatous inflammation associated with multiple budding yeast-like organisms consistent with Paracoccidioides spp., confirmed by Grocott staining. Molecular analysis of formalin-fixed, paraffin-embedded (FFPE) tissue by polymerase chain reaction (PCR) detected Paracoccidioides spp., and the resulting Sanger sequences clustered with reference sequences of the Paracoccidioides brasiliensis complex in the ITS-based phylogenetic analysis. Conclusion This case demonstrates severe disseminated PCM in an endangered Neotropical primate and highlights the diagnostic value of combining histopathology and molecular assays in FFPE samples for etiological confirmation of fungal infections.