Cutaneous phaeohyphomycosis in a dog caused by Scolecobasidium dracaenae : a case report of a rarely identified dematiaceous fungus

Introduction Phaeohyphomycosis is an opportunistic infection caused by melanized fungi, primarily affecting immunocompromised hosts. Accurate identification is challenging due to morphological similarities among species, often leading to misidentification. Case presentation A 7.6-year-old immunocompromised Shetland Sheepdog, receiving prednisolone and ciclosporin for sterile nodular panniculitis, presented with a solitary purulent subcutaneous nodule on the right flank. Histopathology of an excisional biopsy revealed pyogranulomatous inflammation with pigmented septate fungal hyphae, consistent with phaeohyphomycosis. Fungal culture produced black, powdery colonies within four days incubation. Initial morphological identification suggested Exophiala spp., later revised to Verruconis gallopava by a reference laboratory. Definitive identification was achieved by sequencing of the internal transcribed spacer (ITS) and β-tubulin gene regions, confirming Scolecobasidium dracaenae. Antifungal susceptibility testing, performed according to EUCAST guidelines, demonstrated high minimum inhibitory concentrations (MICs >8 mg/L) to all agents tested. Conclusion This case highlights the limitations of conventional identification methods and the importance of molecular diagnostics for rare fungal pathogens. Despite in vitro antifungal resistance, successful resolution was achieved with surgical management and topical therapy. To the authors’ knowledge, this represents the first reported canine infection caused by S. dracaenae.