December 13, 2013

Guideline Management of Ring-Enhancing Lesions in Immunocompromised Host

The differentials for peripheral or ring enhancing cerebral lesions includes cerebral abscess, tuberculoma, neurocysticercosis, metastasis, glioblastoma, subacute infarct/haemorrhage/contusion, demyelination (incomplete ring), tumefactive demyelinating lesion (incomplete ring), radiation necrosis, postoperative change, lymphoma - in an immunocompromised patient, leukaemia, thrombosed aneurysm, and necrotising leukoencephalopathy after methotrexate.

This article is for Medical Students & Professionals
This is a Question & Answer revision article designed for medical students and professionals preparing for the PLAB, MRCP or USMLE examinations. They are based on actual questions from these examinations. You may find the Brain and Nerve articles more useful, or one of our many articles on Diseases & Conditions, Medical Syndromes, Health & Wellness or Home Remedies.
In this article:
MCQ exam: clinical scenario
MCQ exam: answer
MCQ exam: explanation

MCQ exam: clinical scenario

A 35-year-old woman is referred to a tertiary hospital for a brain biopsy. The patient initially presented to a local community hospital following 5 days of blurred vision associated with headache and 2 days of left face, arm, and leg numbness. These symptoms had come on gradually, were becoming progressively worse, and were accompanied with generalized fatigue and anxiety. She also complained of a dry cough and dyspnea on exertion. She denied any fever, chills, night sweats, or weight loss. She reported no contacts with other sick individuals and no recent travel outside her hometown. She did not own any pets.

Past Medical History: The patient had diabetes mellitus type 2. She had undergone a hysterectomy a few years earlier for cervical cancer. She also had been diagnosed with pulmonary alveolar proteinosis (PAP).

Lab Tests: Among the numerous lab tests, it was confirmed she was HIV-negative. Toxoplasma immunoglobulin (Ig)M and IgG were negative. Routine blood cultures were negative.

Imaging Studies: The patient underwent head computed tomography (CT) and magnetic resonance imaging (MRI) of the brain. These showed multiple, bilateral lesions with surrounding edema on fluid-attenuated inversion recovery (FLAIR) images, which appeared ring-enhancing on postgadolinium images.

According to the American Academy of Neurology (AAN) guidelines, what is the next best step for the management of ring-enhancing lesions in the immunocompromised host?

a). Go directly to brain biopsy
b). Treat empirically for toxoplasmosis
c). Treat empirically for pyogenic abscess
d). Treat empirically with steroids
e). Treat empirically with high dose antibiotics

MCQ questions & answers on medicalnotes.info

MCQ exam: answer

The correct answer is B.
According to AAN guidelines (1998), treat empirically for toxoplasmosis

MCQ exam: explanation

The general consensus is that no noninvasive approach has emerged as being able to reliably discern whether a ring-enhancing lesion is tumor or abscess, and therefore early biopsy is generally considered essential for definitive diagnosis. The only exception to this rule is stated in the AAN guidelines for the management of patients with AIDS. In this case, only an isolated ring-enhancing lesion in the setting of negative toxoplasmosis serology requires early biopsy. Otherwise, a trial of pyrimethamine and sulfadiazine is considered appropriate for treatment of presumptive toxoplasmosis.

A helpful mnemonic for causes of ring-enhancing brain lesions is MAGIC DR. See also the separate article, Differential Diagnoses Of Ring Enhancing Lesions.

Reference(s)
1). Irene Cortese, MD, Fellow and Avindra Nath, MD, Professor: Case 11: A Young Woman With Ring-Enhancing Brain Lesions. MedGenMed. 2006; 8(1): 3. Published online 2006 Jan 5. PMCID: PMC1681925 PMID: 16915133
2). Radiopaedia: Cerebral ring enhancing lesions. Available online: https://radiopaedia.org/articles/cerebral-ring-enhancing-lesions

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