Cerebral phaeohyphomycosis due to Rhinocladiella mackenziei in an immunocompetent patient: A case report and review of literature

Abstract

Background: Rhinocladiella mackenziei is a neurotropic fungus which is unique in its ability to cause a devastating cerebral infection with upto 100% fatality rate both in immunocompromised and immunocompetent individuals despite aggressive treatment with surgery and intensive antifungal therapy. Cerebral phaeohyphomycosis formation of pus and black necrotic debris leading to development of brain abscesses. Rhinocladiella mackenziei is difficult to isolate in laboratory as it grows slowly in culture medium, requiring skill to diagnose it. Case description: A 42-year-old Pakistani man presented with left frontal and retro-orbital headache, left facial numbness and progressive right upper limb weakness and speech difficulty. Magnetic resonance imaging (MRI) of Brain with contrast showed a space occupying lesion in the basal ganglia region. All other workup was unremarkable. He underwent neuronavigation guided supratentorial craniotomy for biopsy and excision of the left thalamic space occupying lesion. Histopathology of specimen revealed abscess formation with few scattered granulomas showing collections of histiocytes and multinucleated giant cells. Periodic Acid-Schiff (PAS) special stains highlighted numerous septate fungal hyphae. Culture later grew Rhinocladiella Mackenziei. He developed complications during his hospital stay but is currently stable and is being treated with Amphotericin and Posaconaole along with neurorehabilitation therapy. Discussion:Rhinocladiella mackenziei, has been recognized to cause cerebral phaeohypomycosis. It has been suggested that inhalation of fungal spores is presumed source of entry of the organism. Our patient had a single ring enhancing lesion in the basal ganglia region.Upon operation the infected area looks greenish-brown in color with thick wall abscess cavity containing purulent material.The commonly used antifungal agents are amphotericin B, posaconazole, voriconazole and itraconazole.Our patient received amphotericin and posaconazole.The treatment duration varies from 3 months to a year and is guided by complete resolution of symptoms and radiological findings.Our patient's GCS has improved but right sided weakness and aphasia persists upon completion of one month of treatment. Conclusion: Rhinocladiella mackenzei brain abscess is a devastating infection with significant morbidity and mortality and should be suspected in patients presenting with brain abscess from high endemic areas.