Abscess Formation in Metastatic Brain Tumor with History of Immune Checkpoint Inhibitor: A Case Report

Abstract

We present the case of a 68-year-old man with brain metastasis from lung cancer and a history of immune checkpoint inhibitor administration, with overlapping abscess within the metastatic lesion. He initially received antibiotic treatment under a diagnosis of brain abscess because of a hyper-intense area on diffusion-weighted imaging inside the gadolinium-enhanced wall. The size of the enhanced lesion did not change much, but the extent of perifocal edema decreased after antibiotic treatment. After 2–4 months, the lesion gradually enlarged, and imaging characteristics changed from single cyst to multiple cysts. Surgical resection was performed and pathological examination revealed the lesion as metastasis from the lung tumor. Smear preparation of the tumor contents detected Gram-positive bacilli, confirming the dual pathology of metastasis and brain abscess. Discussing the pathogenesis, we speculated that therapy with durvalumab (MEDI4736), an anti-PD-L1 antibody, induced immune status modification including immunosuppressive regulation, which might have promoted abscess formation.

Diffusion-weighted imaging-based radiomics model using automatic machine learning to differentiate cerebral cystic metastases from brain abscesses

“…Brain abscesses typically exhibit markedly hyperintense signals in cavities with restricted diffusion of contents on DWI, while the cavities of cystic brain tumors generally show hypointense signal. However, some cystic brain metastases have been reported to present high intensity with low apparent diffusion coefficient (ADC) value on DWI because of highly viscous mucin or many inflammatory cells in the cystic cavity (Sakatani et al 2019 ; Takayasu et al 2018 ; Pérez-Riverola et al 2023 ; Hartmann et al 2001 ; Yikilmaz et al 2009 ). In 2010, (Duygulu et al 2010 ) reported that 19.7% of intracerebral metastasis showed hyperintensity for DWI in a larger patient cohort.…”