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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.

Invasive aspergillosis is one of the most important and fatal complications after liver transplant, especially in patients with involvement of the central nervous system. We present a case of a patient who developed cerebral and pulmonary aspergillosis, coinfected with cytomegalovirus, after liver transplant for toxic fulminant hepatitis. The patient was treated successfully with neurosurgical intervention and voriconazole. Voriconazole is considered more effective in cerebral aspergillosis than other anti-fungal agents due to the greater penetration into central nervous system and higher cerebrospinal fluid and brain tissue levels.

Candida species are opportunistic fungi associated with immunosuppression and are the most commonly isolated fungal pathogens from the human central nervous system. Invasive candidiasis is reported uncommonly in animals and there have only been two reports of candidal infection of the brain. This report presents a case of a cerebral candidal abscess in an aborted late-term calf co-infected with bovine viral diarrhoea virus. Candida etchellsii, a species not previously identified as pathogenic, was identified as the causative agent by polymerase chain reaction., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We present a case of Nocardia farcinica brain abscesses in an HIV-positive patient, initially misdiagnosed as cerebral toxoplasmosis. The correct diagnosis was eventually confirmed by brain biopsy. It is debatable as to whether surgical intervention is necessary for diagnosis and treatment of Nocardia abscesses. This case highlights the importance of early neurosurgical input and biopsy to aid correct and timely diagnosis.

We report the case of patient with rheumatoid arthritis treated by sulfasalazin. He was hospitalized because of general erythrodermia and diarrhoea with dysproteinemia. The consciousness disturbances and the meningitis syndrome occured in the course of disease. The findings of cerebrospinal fluid suggested viral meningitis and encephalitis. The treatment was started. After short-term improvement, the focal neurological deficits and the consciousness disturbances appeared again. The examinations of the computed tomography and the magnetic resonance image suggested inflammatory or neoplasmatic process. The inflammatory process seemed to be more probable and antibiotic treatment was administered. The following CT and MRI findings confirmed inflammatory changes of brain tissue and abscess formation tendency. After the neurosurgeon consultation the conservatively treatment was continued. The 2 month therapy achieved a successful outcome. We report this case because of the difficulties of diagnostic and treatment choices and the 50% mortality connected with the multiple brain abscesses. It seems that in our case the bacterial infection was secondary to the viral encephalomeningitis. We couldn't find the primary focus of bacterial infection, although the infection cause was undoubtedly hematogenous (abscesses location on the boundaries of cerebral cortex and white matter). There is no evident therapeutic standards and the choice of the best treatment is still under discussion. However, neuroimagining techniques are very useful in the correct diagnosis and optimal treatment.

Simian virus 40 (SV40) DNA sequences were found, by PCR analysis followed by filter hybridization, in the cerebrospinal fluid of a 29-y-old male affected by AIDS with an undefined cerebral lesion. This case illustrates the need to consider the SV40 polyomavirus among viral agents potentially responsible of encephalitis and neurological disorders in AIDS patients.

Case Report: A boy of 8 suffering from hemoglobinopathy M had two encapsulated cerebral abscesses confirmed on CT--one in the right temporal lobe, the second in the left frontal lobe--measuring 48 and 58 mm in diameter respectively. The disease began with fever, daily vomiting, and permanent somnolency, and was defined as encephalitis of viral etiology., Treatment: Conservative treatment proved ineffective and the patient's state grew worse. He underwent simultaneous excision of the two cerebral abscesses with a capsule. Continuous drainage of the operational cavities was performed., Outcome: The patient has been observed for 3 months.

We have established a mouse experimental brain abscess model using Staphylococcus aureus where lesion sites are greatly exaggerated compared to the localized area of initial infection, reminiscent of an overactive immune response. Here we demonstrate the prolonged expression of IL-1 beta, TNF-alpha, and macrophage inflammatory protein-2 (MIP-2/CXCL2), concomitant with a chronic disruption of the blood-brain barrier (BBB) in mice with S. aureus-induced brain abscess. These changes correlated with the continued presence of infiltrating neutrophils and macrophages/microglia. Collectively these findings suggest that the excessive tissue damage that often results from brain abscess may be mediated, in part, by the perpetuation of antibacterial immune responses that are not downregulated in a timely manner.

Case Report: A 16-year-old male patient who had been treated at the age of 13 months with a ventriculoperitoneal (VP) shunt due to obstructive hydrocephalus was presented to our department for a routine follow-up examination. The patient had tolerated well a shunt disconnection in 1990 and the distal part had been removed. Six years later radiological evaluation revealed an intracerebral mass adjacent to the remaining intraventricular catheter. The mass, histologically classified as an abscess, had to be removed 3 years later due to disease progression, although the patient remained asymptomatic., Discussion: This case is of particular interest because it demonstrates the extremely delayed onset and progressive course of a well-known complication of VP shunt systems in an asymptomatic patient. In addition, the reported case raises the question of whether a non-functioning shunt needs to be removed or not.

Understanding the rationale of contrast media use in MR imaging is based on knowledge of the blood brain barrier (BBB) and the pathophysiology of infectious agents attacking the central nervous system. This article focuses on the relationship between BBB structures and functions in healthy and unhealthy conditions and contrast media in patients with acquired immunodeficiency syndrome.