Year : 2003 | Volume
: 13 | Issue : 3 | Page : 329--330
Radiological quiz - neuroradiology
K Saggar, A Ahluwalia, P Sandhu, K Gupta
Dept of Radiodiagnosis, Dayanand Medical College & Hospital, Ludhiana - 141 001(Punjab), India
125-D, Kitchlu Nagar, Ludhiana-141 001 Punjab
|How to cite this article:|
Saggar K, Ahluwalia A, Sandhu P, Gupta K. Radiological quiz - neuroradiology.Indian J Radiol Imaging 2003;13:329-330
|How to cite this URL:|
Saggar K, Ahluwalia A, Sandhu P, Gupta K. Radiological quiz - neuroradiology. Indian J Radiol Imaging [serial online] 2003 [cited 2021 Jan 28 ];13:329-330
Available from: https://www.ijri.org/text.asp?2003/13/3/329/30478
A 70 year-old woman presented with history of headache for two days followed by altered sensorium. The general physical examination was grossly normal. Central nervous system (CNS) evaluation revealed decreased power in the right lower limb. Plain and contrast enhanced MR of the brain was done as shown below [Figure 1],[Figure 2],[Figure 3]. What is the radiological diagnosis?
Primary Cerebral Lymphoma
T1W saggital image of the brain shows a hypointense mass in the paramedian portion of the frontal lobe and genu of corpus callosum with minimal perilesional edema [Figure 1]. Post-gadolinium axial T1W image shows intense homogenous enhancement of the mass [Figure 2]. Axial FLAIR image at high ventricular level [Figure 3] shows an additional lesion in the left frontal lobe in parasaggital location. This is hyperintense to the gray matter with significant perilesional edema. A homogenously enhancing lesion in central grey matter or the corpus callosum is highly suggestive of CNS lymphoma. Bone marrow aspiration revealed a normocellular normoblastic marrow with no evidence of lymphomatous process. The patient was operated and biopsy of the lesion confirmed the diagnosis of primary cerebral lymphoma (Non-Hodgkin type).
Primary malignant lymphomas of CNS are extra nodal tumors arising in the CNS in patients with no other features suggestive of lymphoma at the time of initial diagnosis.
Primary cerebral lymphoma is rare, representing less than 1.5 percent of all CNS neoplasms. Hodgkin's disease rarely involves the brain, therefore parenchymal intracranial lymphoma is almost exclusively non-Hodgkin's lymphoma . The most common type is diffuse histocystic lymphoma, also known as reticulum cell sarcoma.
Although lymphoma is seen at all ages, the peak incidence in immunocompetent individuals is in the sixth and seventh decades. In patients who have acquired immunodeficiency syndrome (AIDS) or have undergone organ transplantation and are on immunosuppressive therapy, the median age of onset is in the third decade. There is a definite sex predilection, with a 3:2 male to female ratio in immunocompetent patients and 9:1 ratio in patients with AIDS ,. Primary cerebral lymphoma usually present as centrally located deep seated masses. The corpus callosum and the basal ganglia are common sites of involvement. They are often located in close proximity to the ventricles and may infiltrate along the ependymal ventricular walls. Intratumoral hemorrhage and necrosis are uncommon and peritumoral edema is usually mild in immunocompetent patients. However, hemorrhage, necrosis and white matter edema is often extensive in immunocompromised patient due to rapid growth of the lesion.
Histologically, 98% of primary CNS lymphomas are high grade B cell tumors that characteristically demonstrate an angiocentric infiltration pattern in which collars of small neoplastic lymphocytes surround and infiltrate the walls of small penetrating vessels of the brain and the perivascular (Virchow-Robin) extensions of subarachnoid space ,. From the perivascular foci, the tumor cells invade the adjacent neural parenchyma and coalesce forming diffuse masses.
Radiologically, the lymphomatous masses appear homogeneously isodense to moderately hyperdense on pre-contrast CT scan (reflecting densely packed tumor cells with high nuclear to cytoplasmic ratio). These demonstrate strong homogeneous contrast enhancement. This has been explained histologically by the fact that lymphomatous infiltration exhibits perivascular distribution. Thus, the tumor rarely outgrows its blood supply. However, in immunocompromised patients, central necrosis with peripheral enhancement and extensive perilesional edema is observed frequently. Leptomeningeal or ependymal infiltration is seldom recognized on the basis of CT scan alone ,. Even after contrast enhancement it must be inferred by secondary findings such as dilatation of the ventricular system secondary to blockage at the level of convexity.
On MR, most lesions are isointense to hypointense with the gray matter on T1W images and iso- to slightly hyperintense on T2W images. Nevertheless, some lesions may exhibit marked T2 hyperintensity. Almost all primary CNS lymphomas demonstrate intense enhancement after intravenous administration of gadolinium .
The differential diagnosis of primary cerebral lymphoma that appears as multiple peripheral lesions is an infectious lesion like abscess, especially in immunocompromised host or metastasis. A single ring enhancing lesion with extensive peritumoral edema can simulate a high grade glioma or toxoplasmosis, particularly in patients with AIDS .
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