Clinical History
HIV-positive patient presenting with seizure
Imaging Findings
Patient admitted to the emergency department for seizures.
HIV positive serology had been diagnosed 3 years ago.
An MRI study was conducted.
In this clinical and serological context, several findings suggested the diagnosis of lymphoma : location of the lesion into the corpus callosum, lobulated margins, small zone of surrounding edema, marked enhancement.
Since toxoplasmosis is the most frequent affection in this contexte, the patients systematically received anti-toxoplasmic treatment which was uneffective.
The lesion regressed after chemotherapy and radiotherapy, confirming the diagnosis of PCL.
Discussion
PCL account for 1% to 2% of primary central nervous system tumors but their incidence is rapidly rising in both AIDS and non-AIDS patients. Approximately 20% to 40% of these lesions are multiple.
The deep basal gangli, peri-ventricular region and corpus callosum are common sites.
Clinical symptoms vary from seizure, headache, stupor or focal neurologic deficits.
At MRI, most PCL are relatively well-circumscribed focal masses or poorly delineated, diffusely infiltrating lesions involving both deep grey matter nuclei and white matter tract.. They are iso-intense to slightly hypo-intense compared to grey matter on T1-weighted images and are iso to slightly hyper-intense on T2-weighted studies.
Most PCL in AIDS related patients have heterogenous enhancement with hemorrhage and necrotic foci.
The imaging appearances of PCL are not specific and can also be described in other AIDS related pathologies: toxoplasmosis, primary or secondary cerebral neoplasms and brain infections and especially toxoplasmosis, making the differential diagnosis difficult in such context.
In some cases, steteotactic biopsy can also be used to ensure a pathological and a bacteriological proof
Differential Diagnosis List
Primary Cerebral Lymphoma of the Corpus Callosum
Final Diagnosis
Primary Cerebral Lymphoma of the Corpus Callosum