Isolated intracranial fungal mass lesions in immunocompetent subjects mimicking glial neoplasms on magnetic resonance imaging – A case series

Intracranial fungal lesions in immunocompetent hosts without any known primary focus are rare. We present an illustrative case series of intracranial fungal mass lesions in immunocompetent hosts who presented with non-specific symptoms and imaging features that were erroneously diagnosed as neoplasms. We evaluated the imaging features of these infiltrative fungal infections, compared them with neoplastic lesions with similar presentations, and tried to seek imaging features that could help in the differentiation of fungal lesions from neoplastic/ other non-neoplastic etiologies. We speculated that two important signs that may help in raising suspicion of fungal etiology are T2 hypointensity within the lesions and lack of diffusion restriction. T2 hypointensity, when combined with other imaging features such as absence of magnetization transfer hyperintensity and lack of diffusion restriction, may help in differentiating the fungal lesion from neoplastic/other non-neoplastic etiologies. Although relative cerebral blood volume (rCBV)/relative cerebral blood flow values are relatively lower in fungal cerebritis as compared to glioblastoma, fungal lesions can also demonstrate markedly elevated rCBV values that may mimic high-grade neoplasms.