WBR0305
| Author | [[PageAuthor::Mugilan Poongkunran M.B.B.S [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 3 |
| Main Category | MainCategory::Inpatient Facilities |
| Sub Category | SubCategory::Infectious Disease |
| Prompt | [[Prompt::A 28 year old male with AIDS is hospitalised for pneumocystosis carinii pneumonia infection. He was diagnosed with AIDS 1 year back and is on zidovudine, lamivudine and indinavir. The patient is non-compliant with his medications. His vitals are stable and temperature is 101.5 F. He is started on trimethoprim and sulphamethoxazole therapy. On the 3rd day in hospital, he complaints of weakness of the right upper and lower extremities. He also complaints of decreased vision in the right side. An MRI shows a ring enhancing lesion in the left parieto occipital area. What is the most likely cause of this patient’s condition?]] |
| Answer A | AnswerA::Epstein-Barr virus |
| Answer A Explanation | [[AnswerAExp::Incorrect : Primary CNS lymphomas are solitary and multiple mass lesions occur with approximately equal frequency. The majority of lesions display some degree of enhancement that is irregular or patchy. However, diffuse ring enhancement can occur but are very very rare.]] |
| Answer B | AnswerB::JC virus |
| Answer B Explanation | [[AnswerBExp::Incorrect : Progressive multifocal leucoencephalopathy (PML) is usually characterized by multifocal areas of demyelination that are bilateral, asymmetric, and localized preferentially to the periventricular areas and the subcortical white matter. The lesions are generally not contrast-enhancing and are not surrounded by edema; as a result, substantial mass effect on surrounding structures is absent.]] |
| Answer C | AnswerC::Toxoplasma gondii |
| Answer C Explanation | [[AnswerCExp::Incorrect : Toxoplasmosis lesions are generally multiple and are localized in the parietal or frontal lobes, in the thalamus or basal ganglia, or at the cortico-medullary junction. Ring enhancement is present in approximately 90 percent and surrounding edema with mass effect is often seen. Uncommonly, TE can present as a diffuse encephalitis, which is not associated with focal abscess formation]] |
| Answer D | AnswerD::Streptococci pneumonia |
| Answer D Explanation | [[AnswerDExp::Correct : Diffusion-weighted MR imaging (DWI) is capable of differentiating ring-enhancing lesions due to brain abscess from neoplastic lesions. Abscesses are usually hyperintense when compared to neoplasms which are hypointense.]] |
| Answer E | AnswerE::HIV |
| Answer E Explanation | [[AnswerEExp::Incorrect : HIV encephalopathy presents with dementia and focal neurological deficits are uncommon.]] |
| Right Answer | RightAnswer::D |
| Explanation | [[Explanation::There are various etiologies for CNS disease in the HIV-infected patient. The leading diagnostic considerations in a patient with advanced immunosuppression are Toxoplasma encephalitis, primary CNS lymphoma, progressive multifocal leukoencephalopathy, HIV encephalopathy, and CMV encephalitis. The two leading diagnoses associated with mass effect in developed countries are Toxoplasma encephalitis and primary central system lymphoma. In the developing world, tuberculomas are a leading diagnostic consideration, however brain abscess though common after trauma to head, can occur as a spread from adjacent structure or from an active source. Educational Objective: If there is a single lesion on the brain MRI of an immunocompromised host, it is most likely to be a brain abscess. |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |