Background:

Cladosporium cladosporioides is a pigmented environmental fungus rarely implicated in central nervous system (CNS) infections. Its atypical presentation often leads to misdiagnosis, especially when mimicking skull base neoplasms.

Case Presentation:

A 27-year-old immunocompetent male carpenter from Jalpaiguri, West Bengal, presented with progressive headaches, retro-orbital pain, diplopia, and sixth cranial nerve palsy. Imaging revealed a destructive clival lesion with intracranial extension, initially suspected to be a chordoma. Nasal endoscopic biopsy showed pigmented septate hyphae. Culture and mass spectrometry confirmed Cladosporium cladosporioides. The patient responded dramatically to intravenous followed by oral antifungal therapy, with complete symptom resolution within 72 hours and no relapse over four weeks.

Conclusion:

This case underscores the importance of considering fungal etiologies in skull base lesions, even in immunocompetent individuals. Early microbiological diagnosis and prompt antifungal treatment are crucial. A multidisciplinary approach is essential for accurate diagnosis and effective management of rare CNS fungal infections.