|Case 16 :|
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Study shows multiple hypointense lesions (T1WI), hyperintense on T2WI, with a few showing poor margins. All lesions are seen in close approximation to ventricular ependyma / subarachnoid spaces.
The incidence of CNS lymphoma is higher in the immunocompromised patient. There is no single uniform pattern of involvement by primary cerebral lymphoma, and patterns range from solitary or multiple, circumscribed nodules to diffuse infiltration or widespread distribution.
hallmark of CNS lymphoma is its hyperdensity on NCCT, its periventricular
localization, and its fluffy pattern of contrast enhancement (Fig 2).
Almost all lymphomas are in direct contact with either the ventricular
ependyma or the superficial subarachnoid space. Tumor margins are usually
poorly defined, due to the characteristic perivascular infiltration
pattern of the tumor cells. On CT, lesions are hyperdense with a
homogenous enhancement, while on MR, they exhibit slight hypointensity on
T1WI, and hypo to slightly hyperintense on T2WI and PD-WI, relative to
gray matter. Common location is basal ganglia or temporal lobes, while for
secondary lymphoma is the cerebral meninges.
AIDS patient, lymphomas are sometimes indistinguishable from other
lesions, and the situation is further complicated by the frequent presence
of combined pathology, i.e. toxoplasmosis and lymphoma.
between lymphoma and Toxoplasmosis
is more likely when the enhancing lesion is subependymal, periventricular
or in the corpus callosum. Rapid progression in short intervals also
favors lymphoma. Enhancing lesions in the basal ganglia or the
corticomedullary junction are more likely due to Toxoplasma gondii.
practice for AIDS patients with enhancing CNS lesions by CT/MR and
positive toxoplasma serology is an empirical cause of antitoxoplasmosis
treatment for 10 to 21 days. If no clinical and/or radiographic response
occurs, alternative diagnoses are considered more closely.
AIDS patients with primary CNS lymphoma this approach has a significantly
negative impact on morbidity and duration of survival, as these patients
have only an average survival time of 4 months with radiation therapy and
1.5 months without radiation therapy. A fast and accurate differentiation
between lymphoma and infectious causes is of vital importance for this
of functional MRI and SPECT:
dynamic contrast fMRI, few researchers have found increased rCBV in
regions with active lymphoma but reduced rCBV in the central regions of
toxoplasmosis lesions. The rise within active lymphoma probably results
from hypervascularity within the tumor, and the drop within toxoplasmosis
lesions probably reflects lack of vasculature. This method of evaluation
is useful in differentiating between the two.