Presentation
Right lower limb weakness and altered mental status. Newly diagnosed retroviral infection with a CD4 count of 15cell/ul.
Patient Data
Ill-defined, avidly enhancing masses with nodular ring enhancing component predominantly in the left basal ganglia and periventricular white matter, and demonstrated subependymal extension and crossing of the corpus callosum. There is perilesional vasogenic edema and diffusion restriction of the enhancing component, along with non-enhancing and non-diffusion restricting necrotic component. Mild midline shift to the right.
Impression: the findings are suggestive of primary CNS lymphoma with a differential diagnosis of butterfly glioma/glioblastoma.
After a week of treatment with dexamethasone, the patient showed clinical and radiological improvement.
Mild reduction in volume of the mass with associated proportional reduction in vasogenic edema and midline shift.
Case Discussion
Acquired form of immunodeficiency-associated CNS lymphoma is a subset of primary CNS lymphoma which is mostly due to HIV/AIDS, as in this case. It occurs when the CD4 count is less than 50cells/ul. They have a good initial response for steroid treatment, though generally have poor prognosis. The response to steroids can be used to retrospectively confirm the radiological diagnosis.
Radiological differential diagnosis in this case was butterfly glioma/glioblastoma. The large necrotic component of the mass was suggestive of glioma than lymphoma, though lymphoma in immunocompromised can also have necrotic component. Biopsy was done in this patient after two weeks of steroid treatment and the histopathology result was negative. It is advised to withhold steroids , if possible, before biopsy of lymphoma as steroid reduces the diagnostic yield by up to 50%.
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