Atypical pyogenic brain abscess evaluation by diffusion-weighted imaging: diagnosis with multimodality MR imaging

Intracranial peripherally enhancing lesions in cardiac transplant recipients: A rare case series and literature review

Intracranial peripherally enhancing lesions in immunosuppressed solid organ transplant recipients represent a unique diagnostic and management dilemma due to the vast array of differentials that demand consideration. Diagnosis of the underlying pathology is often guided by the use of magnetic resonance imaging (MRI). We present the first published case series of three cardiac transplant recipients with significantly atypical neuroradiological findings contrary to the tenets of contemporary literature. Our rare case series consists of: (1) A sterile Mycobacterium pyogenic abscess mimicking glioblastoma multiforme due to an immunosuppressed state (2) Epstein Barr Virus encephalitis masquerading as Central Nervous System Post-Transplant Lymphoproliferative Disorder (3) An unusual case of partially treated disseminated Nocardiosis warning of the need to consider the immunosuppressed state and partial treatment response obfuscating classical MRI appearances. We utilise these unprecedented cases as the basis of a literature review to understand the pathophysiology behind the peculiar imaging findings in this rarefied cohort of transplant recipients, and rationalise why the MRI findings in each instance contradicts the accepted imaging patterns. In the setting of potential unreliability of neuroradiology in this immunosuppressed unique subgroup, we hope to impart to clinicians that definitive diagnosis obtained by emergent neurosurgical intervention may be necessary to accurately and expediently guide further medical management.

Nocardia amikacinitolerans and cytomegalovirus: distinctive clinical and radiological characterization of the rare etiologies of brain abscesses: report of 2 cases

Central nervous system infections in immunosuppressed patients are rare but potentially lethal complications that require swift diagnoses and intervention. While the differential diagnosis for new lesions on neuroradiological imaging of immunosuppressed patients typically includes infections and neoplasms, image-based heuristics to differentiate the two has been shown to have variable reliability.The authors describe 2 rare CNS infections in immunocompromised patients with atypical physical and radiological presentations. In the first case, a 59-year-old man, who had recently undergone a renal transplantation, was found to have multifocal Nocardia amikacinitolerans abscesses masquerading as neoplasms on diffusion-weighted imaging (DWI); in the second case, a 33-year-old man with suspected recurrent Hodgkin's lymphoma was found to have a nonpyogenic abscess with cytomegalovirus (CMV) encephalitis.As per review of the literature, this appears to be the first case of brain abscess caused by N. amikacinitolerans, a recently isolated superbug. Despite confirmation through brain biopsy later on in case 1, the initial radiological appearance was atypical, showing subtle diffusion restriction on DWI. Similarly, the authors present a case of CMV encephalitis that presented as a ring-enhancing lesion, which is extremely rare. Both cases draw attention to the reliability of neuroimaging in differentiating an abscess from a neoplasm.

Intracranial Infectious and Inflammatory Diseases Presenting as Neurosurgical Pathologies

There are many infectious and inflammatory processes affecting the central nervous system that can simulate other neurosurgical pathologies (e.g. tumor) and may precipitate a brain biopsy for definitive diagnosis if not suspected a priori. The challenge for the healthcare team is to recognize imaging features that support a nonsurgical pathology to avoid unnecessary interventions. This review aims to give a general overview of some common inflammatory and infectious entities that affect the central nervous system, with illustrative examples and highlighting important pearls and pitfalls.

Brain Abscess Showing a Lack of Restricted Diffusion and Successfully Treated with Linezolid

A 59-year-old patient with a history of hepatocellular carcinoma presented with decreased consciousness and left hemiparesis. A rim-enhanced mass lesion without diffusion restriction was observed in contrast-enhanced MRI including diffusion-weighted imaging. Based on these findings, metastatic brain tumor was suspected. However, brain abscess (BA) was diagnosed after multiple bacterial colonies were observed in aspiration biopsy. Initial conventional antibiotic treatment including vancomycin had failed, so linezolid was used as second-line therapy. As a result, infection signs and clinical symptoms were resolved. We report a case with atypical imaging features and antibiotic susceptibility of a BA in an immunocompromised patient undergoing chemotherapy.

Pyogenic brain abscess with atypical features resembling glioblastoma in advanced MRI imaging

Differentiation between infectious and neoplastic brain processes is crucial for treatment planning. Advanced magnetic resonance imaging techniques, such as diffusion, perfusion, susceptibility weighted imaging, and magnetic resonance spectroscopy, enhance the imaging differences between these two pathologies. However, despite the utilization of these advanced techniques, the pathologic process may be confound by atypical findings. Here, we report a case of an autistic patient with multiple brain lesions with diffusion weighted imaging, susceptibility weighted imaging, and perfusion patterns resembling features of a multicentric glioblastoma, which were confirmed surgically, neuropathologically, and bacteriologically as brain abscesses. We discuss the differentiation of these different entities in the light of advanced magnetic resonance imaging techniques.