Central nervous system lymphoma: histologic types and CT appearance

Lymphoma masquerading as occlusive retinal vasculitis: A case study

Purpose

To describe a case of retinal lymphoma presenting as an occlusive retinal vasculitis without vitritis that was exquisitely responsive to intravitreal dexamethasone implant (IVDI).

Observation

A 66-year old male presented with decreased vision in the right eye and was diagnosed with occlusive retinal vasculitis and prominent cystoid macular edema though he lacked vitritis. A complete systemic workup for infectious, inflammatory, and infiltrative etiologies was unremarkable. Intravenous methylprednisolone and cyclophosphamide had no clinical effect. Due to persistent perivascular exudates and refractory macular edema, IVDI was administered with marked improvement in vision and clinical findings. Subsequent retinal vasculitis in the left eye responded to IVDI as well. The patient remained disease free for months while on weekly adalimumab. He then presented with acute vision loss in the left eye due to a lymphomatous subretinal infiltration and a new lesion in the corpus callosum. He has remained disease free for more than two years after intravitreal methotrexate injections and rituximab with an autologous stem cell transplant.

Conclusion and importance

Lymphoma may present as an occlusive retinal vasculitis without vitritis and can be masked due to its response to IVDI.

Eye involvement in primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) may manifest initially in the eye (termed vitreoretinal lymphoma or VRL) or in non-ocular CNS compartments, or in both. The nature of the onset of PCNSL implies two clinical specialists - ophthalmologists and neuro-oncologists - independently may assess the primary presentation of this rare malignancy. Clinically relevant perspectives on expectations of PCNSL manifestation in both ocular and non-ocular CNS compartments would help inform management practices in each specialty, which should impact clinical outcomes. A recent increase in the number of published PCNSL cohort studies provides new opportunity to review the current prevalence rates of ocular involvement, and the timing of this involvement over the course of disease. In PCNSL cohorts defined by non-ocular CNS compartment involvement, with or without ocular involvement (termed "PCNSL ± ocular involvement" cohorts), mean rates of concomitant VRL at diagnosis, or at any time during the course, are 10% and 16%, respectively. Only a few individuals within this cohort group present with exclusive eye disease (<5%), and the rate of secondary ocular involvement is only 5-9%. In PCNSL cohorts defined by the involvement of the ocular compartment, with or without non-ocular CNS involvement (termed "VRL ± non-ocular CNS involvement" cohorts), 58% of persons have a primary ocular diagnosis, which carries a 50% risk of secondary involvement in the CNS beyond the eye. Rates of non-ocular CNS involvement with VRL at diagnosis or over the course of disease are 41% and 69%, respectively.

Primary Cerebral Lymphoma: A Retrospective Study in 22 Immunocompetent Patients

Aims and background

Primary CNS lymphomas are uncommon tumors in immunocompetent patients. We describe the radiological features that should orient towards performing a biopsy and analyze the results in our series of patients.

Methods

We reviewed 22 immunocompetent patients with primary central nervous system lymphoma admitted in our Institute between 1977 and 1997. The follow-up period ranged from 2 months (patient deceased) to 69 months. Fourteen patients underwent surgical removal of the tumor and the remainder a biopsy. All patients received radiotherapy and 8 patients radiotherapy plus chemotherapy.

Results

Two of the 14 patients treated by surgical removal of the tumor died. There was no mortality related to biopsy procedures. Patients treated with radiotherapy had 1-year, 2-year and 5-year survival rates of 66%, 41.6% and 16.6%, compared to 87.5%, 62.5% and 50%, respectively, for patients who received radiotherapy and chemotherapy.

Conclusions

At present, there is no definite treatment for these highly malignant brain tumors. The most favorable results seem related to biopsy followed by radiotherapy plus chemotherapy versus surgical removal, which is related to a high risk of severe postoperative deficit for both the deep location and infiltrating nature of these lesions.

18F-FDG PET/CT in primary brain lymphoma

The actual role of 18F-FDG PET/CT in evaluating primary brain lymphoma is still an open issue. Brain lymphoma usually show elevated 18F-FDG uptake, often higher than other brain tumors or inflammatory processes, but the metabolic behavior of this lymphoma is not still understood. Our aim was to investigate the particular metabolic behavior of this lymphoma. Forty six patients (21 female, 25 male) with histologically-confirmed brain lymphoma who underwent 18F-FDG PET/CT from vertex to the mid-thigh for initial staging were retrospectively evaluated. The PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio, lesion-to-blood pool SUVmax ratio and the tumor to normal brain uptake ratio (T/N ratio) and compared with epidemiological (age, sex, HIV infection) and morphological (tumor size, MRI appearance) characteristics. Thirty-eight patients (83%) had positive 18F-FDG PET/CT (average SUVmax was 15.6 ± 9.2; lesion-to-liver SUVmax ratio 5.8 ± 2.8; lesion-to-blood pool SUVmax ratio 7.1 ± 3.8, T/N ratio 3.1 ± 1.7) at the corresponding brain lesion; the remaining 8 (17%) were not 18F-FDG avid. 18F-FDG avidity was significantly associated with morphological appearance and tumor size and not correlated with other features. 18F-FDG PET/CT detected extracranial disease in two cases (4%) with negative bone marrow biopsies and CT. In conclusion, brain lymphomas are 18F-FDG avid in 83% of cases showing high 18F-FDG uptake and 18F-FDG avidity is correlated with tumor size and morphological appearance of the lesion. PET/CT helped to recognize extracranial disease in two patients.

Primary vitreoretinal lymphoma

Primary vitreoretinal lymphoma (PVRL) is an uncommon, but potentially fatal intraocular malignancy, which may occur with or without primary central nervous system lymphoma (PCNSL). Considered to be a subset of PCNSL, it is mostly of diffuse large B-cell type. The diagnosis of PVRL poses a challenge not only to the clinician, but also to the pathologist. Despite aggressive treatment with chemotherapy and/or radiotherapy, relapses or CNS involvement are common.

Linfoma del sistema nervoso centrale in corso di AIDS

Il linfoma primitivo cerebrale (LPC) è la più comune delle neoplasie opportunistiche del SNC in pazienti AIDS, seguito dal linfoma di Kaposi e dai gliomi, e spesso rappresenta la patologia rivelatrice della condizione di immunodeficienza acquisita.

L'incidenza dei LPC è in costante aumento nelle ultime due decadi. Attualmente rappresentano il 6,6–15,4% di tutti i tumori cerebrali primitivi contro il 3,3% registrato prima del 1978. Nei pazienti AIDS, ha una frequenza compresa fra il 3% ed il 10%. Si tratta, peraltro, di una patologia ancora relativamente rara costituendo solo lo 0,7–0,9% di tutti i linfomi.

I LPC si localizzano in prevalenza in regione sopratentoriale (90%) specialmente nella sostanza grigia periventricolare e nella sostanza bianca; la localizzazione in fossa cranica posteriore è stimata intorno al 10%. Nel LPC l'interessamento leptomeningeo non è comune riscontrandosi in circa il 12% dei casi; più raro il coinvolgimento durale, rarissimo (circa 1%) il coinvolgimento del midollo spinale. Viceversa il linfoma secondario tende ad invadere la dura madre e le leptomeningi.

Il LPC in corso di AIDS si manifesta in forma multifocale fra il 50 ed il 75%.

Dal 1991 è stata documentata una quasi costante associazione del virus di Ebstein-Barr (EBV) con il LPC il che ha indotto a considerare la possibilità di usare l'EBV come un marker diagnostico di tale patologia.

La costante presenza del EBV nel LPC in immunodepressi è in contrasto con quanto visto negli immunocompetenti ove l'associazione è modesta.

Ad una valutazione macroscopica il LPC si manifesta come massa nodulare con consistenza molto variabile da friabile a solida e superficie granulare. La lesione è frequentemente circondata da edema, comunemente diffonde alla leptomeninge e alle regioni subpiali. È multifocale nel 11–50% dei pazienti immunocompetenti e nel 41–81% dei pazienti AIDS nei quali peraltro l'incidenza di multifocalità può raggiungere il 100%.

All'analisi istologica il LPC mostra strati uniformi di cellule neoplastiche, strettamente stipate; il processo di infiltrazione si diffonde ben oltre i margini macroscopici della lesione. Necrosi ed emorragie sono molto più frequenti nei pazienti immunocompromessi.

Neuroradiologicamente le lesioni risultano tipicamente iperdense alla TC e questo aspetto è attribuito ad un alto rapporto nucleo-citoplasma ed ad un elevata cellularità fittamente stipata. Dopo mdc praticamente tutti i LPC mostrano impregnazione la cui intensità è peraltro variabile e talora così debole e indefinita da non essere apprezzata se non utilizzando appropriate finestre.

In RM nelle immagini T1 la lesione è tipicamente da ipo- ad isointensa relativamente alla sostanza grigia e produce un effetto massa modesto rispetto alle sue dimensioni.

Nei primi riferimenti della letteratura tali lesioni erano descritte quasi uniformemente iperintense in T2. Più recentemente, e probabilmente in rapporto ad un affinamento del software che ha consentito una maggiore evidenza di fini dettagli, le lesioni si documentano prevalentemente iso-ipointense alla sostanza grigia in T2, aspetto che, come alla TC, riflette l'alto rapporto nucleo- citoplasma e l'elevata cellularità fittamente stipata.

Nella popolazione non AIDS il LPC mostra quasi costantemente alla RM un impregnazione dopo mdc che risulta omogeneo nei 2/3 dei casi.

Nella popolazione AIDS il LPC mostra impregnazione nel 100% dei casi che risulta disomogeneo nel 54% dei casi, con un pattern anulare nel 46% ed uno irregolare nell '8%.

Uno degli aspetti caratteristici del LPC è la tendenza a diffondere lungo l'ependima, le meningi o entrambe. Questa dtffusione è documentata in percentuali variabili che raggiungono il 75% e si attestano al 28% per la contiguità con la superficie ependimale e 1′8% per la contiguità con la meninge.

FDG-PET/CT in lymphoma

Lymphomas are a heterogeneous group of diseases that arise from the constituent cells of the immune system or from their precursors. 18F-fludeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is now the cornerstone of staging procedures in the state-of-the-art management of Hodgkin's disease and aggressive non-Hodgkin's lymphoma. It plays an important role in staging, restaging, prognostication, planning appropriate treatment strategies, monitoring therapy, and detecting recurrence. However, its role in indolent lymphomas is still unclear and calls for further investigational trials. The protean PET/CT manifestations of lymphoma necessitate a familiarity with the spectrum of imaging findings to enable accurate diagnosis. A meticulous evaluation of PET/CT findings, an understanding of its role in the management of lymphomas, and knowledge of its limitations are mandatory for the optimal utilization of this technique.

Primary intraocular lymphoma

Primary intraocular lymphoma (PIOL) is an ocular malignancy that is a subset of primary central system lymphoma (PCNSL). Approximately one-third of PIOL patients will have concurrent PCNSL at presentation, and 42-92% will develop PCNSL within a mean of 8-29 months. Although rare, the incidence has been rising in both immunocompromised and immunocompetent populations. The majority of PIOL is diffuse large B-cell lymphoma, though rare T-cell variants are described. Recently, PIOL has been classified by main site of involvement in the eye, with vitreoretinal lymphoma as the most common type of ocular lymphoma related to PCNSL. Diagnosis remains challenging for ophthalmologists and pathologists. PIOL can masquerade as noninfectious or infectious uveitis, white dot syndromes, or occasionally as other neoplasms such as metastatic cancers. Laboratory diagnosis by cytology has been much aided by the use of immunocytochemistry, flow cytometry, biochemical finding of interleukin changes (IL10:IL6 ratio > 1), and cellular microdissection with polymerase chain reaction amplification for clonality. Use of several tests improves the diagnostic yield. Approaches to treatment have centered on systemic methotrexate-based chemotherapy, often with cytarabine (Ara-C) and radiotherapy. Use of intravitreal chemotherapy with methotrexate (0.4 mg/0.1 mL) is promising in controlling ocular disease, and intravitreal rituximab (anti-CD20 monoclonal antibody) has also been tried. Despite these advances, prognosis remains poor.

MRI evaluation of pathologies affecting the corpus callosum: A pictorial essay

The corpus callosum is a midline cerebral structure and has a unique embryological development pattern. In this article, we describe the pathophysiology and present imaging findings of various typical/atypical conditions affecting the corpus callosum. Since many of these pathologies have characteristic appearances on magnetic resonance imaging (MRI) and their therapeutic approaches are poles apart, ranging from medical to surgical, the neuroradiologist should be well aware of them.

Primary central nervous system lymphoma

INTRODUCTION

Primary central nervous system lymphoma is a rare subtype of extranodal non-Hodgkin lymphoma that accounts for 4% of central nervous system tumours.

PATIENTS AND METHODS

Retrospective review of 24 patients diagnosed with primary central nervous system lymphoma between 1990 and 2010. All patients were diagnosed using magnetic resonance imaging and the diagnosis was confirmed surgically.

RESULTS

Of the 24 patients analysed, all except 4 were immunocompetent. Median age at diagnosis was 59.3 years (range 13-79) and the sex ratio (male to female) was 1:1.1. Cognitive decline (in 33.4%) and headache (in 25%) were the most common complaints. Diagnosis was performed In 13 cases (54%) following craniotomy and in the other 11 cases (46%) after stereotactic biopsy. Breakdown by pathology was as follows: 22 cases of B-cell lymphoma (91.6%), 1 case of anaplastic large-cell lymphoma, and 1 case of T-cell lymphoma. Mean survival time was 12.8 months with an overall 1-year survival rate of 37.5%.

CONCLUSIONS

Primary central nervous system lymphoma often presents in the sixth decade with cognitive decline, headache, and focal neurological deficits. A single intracranial lesion was present in 75% of the patients (18 cases), and the remaining 25% (6 cases) had between 2 and 4 lesions. Preoperative clinical status was the most important factor determining prognosis.

Imaging tumors of the pediatric central nervous system

Primary tumors of the central nervous system (CNS) are the second most common neoplasms in children and the leading cause of death in this patient population. The primary objective of this article is to describe the most common pediatric brain tumors and to offer an overview of their respective imaging features, primarily on magnetic resonance imaging. Precise anatomic characterization is essential for developing an appropriate differential diagnosis. Once equipped with this critical information, physicians should be better able to make firm diagnoses, leading to improved disease management and patient outcomes in the setting of CNS tumors of childhood.

MRI findings of primary CNS lymphoma in 26 immunocompetent patients

Objective

To record the MR imaging features of primary central nervous system lymphoma (PCNSL) and compare these features in monofocal and multifocal disease.

Materials and Methods

Twenty-one cases of monofocal disease were compared to five cases of multifocal disease. All patients were examined by non-enhanced and contrast-enhanced MRI. Tumor location, tumor size, signal intensity, enhancement characteristics, age distribution, peritumoral edema, cystic changes, and the presence of calcifications were assessed. The MRI features were compared between the monofocal and multifocal disease cases.

Results

The 26 cases, including both the monofocal and multifocal cases, exhibited 37 lesions. Contrast-enhanced images showed variable enhancement patterns: homogeneous enhancement (33 lesions), ring-like enhancement (2), and 'open-ring-like' enhancement (2). The 'notch sign' was noted in four of 33 homogeneously enhancing lesions. One case of hemorrhage and three cases of cystic formation were observed. Intra-tumoral calcification was not found. The frontal lobe, the corpus callosum and the basal ganglia were commonly affected in both the monofocal and multifocal groups. Tumor size differed significantly between the two groups (t = 3.129, p < 0.01) and mildly or moderately enhanced lesions were more frequently found in the monofocal group (p < 0.05). There was no statistical difference between perifocal edema (p > 0.05) and the signal characteristics (p > 0.05) between the two groups.

Conclusion

Our data show that PCNSL has a variable enhancement pattern on MR images. We first reported two lesions with an 'open-ring' enhancement as well as four cases with a 'notch sign'. Monofocal PCNSL cases typically have larger sized tumors with mild or moderate enhancement.

Importance of functional MRI and the role of stereotactic biopsy in the diagnosis of cerebral lymphoma

Primary cerebral lymphoma has varied clinical and imaging presentations making the neuroradiologic diagnosis of primary cerebral lymphoma a challenge. We discuss here three cases of cerebral lymphoma, one primary and two secondary. Our aim is to highlight the importance of diffusion, perfusion and spectroscopy in addition to conventional morphological MRI, and the role of stereotactic biopsy in reaching a correct diagnosis.

Imaging of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is an aggressive neoplastic process that occurs in both immunocompetent and immunocompromised patients. Over the past 30 years there has been a steady increase in the number of cases in both patient populations. The imaging features for the disease and demographic characteristics within these patient populations vary, and in this article the authors describe the salient features of these two groups.

An endoscopically proven ventriculitis-type, cyst-like intraventricular primary lymphoma of the central nervous system

Primary ventriculitis form of primary CNS lymphoma (PCNSL) is very rare and difficult to diagnose from radiological findings. A 55-year-woman presented with a cystic mass in the lateral ventricle without evidence of demonstrable malignant cells in the cerebrospinal fluid (CSF). The endoscopic biopsy showed a ventriculitis-like thin web on the surface of the ventricular wall around the foramen of Monro, resulting in obstruction. Pathological diagnosis was non-Hodgkin's lymphoma, B cell type. This case suggests that PCNSL should be considered as a differential diagnosis for a cystic ventricular lesion even with no malignant cells in the CSF.

Central nervous system lymphoma in children

This paper describes the rare MR and CT features of central nervous system (CNS) lymphoma in immunocompetent children and in survivors of childhood acute lymphoblastic leukemia (ALL) and discusses the causative role of cranial irradiation and/or leukoencephalopathy preceding central nervous system (CNS) lymphoma in survivors of childhood leukemia. The authors reviewed MR and CT scans of 3 children with biopsy-proved CNS lymphoma. One child had tumor infiltration within the optic nerve sheaths and optic chiasm by previously known non-Hodgkin lymphoma. In 2 patients, CNS lymphoma developed 8 and 10 years after initial ALL treatment. In both cases CNS lymphoma was preceded by cranial irradiation and leukoencephalopathy. A single lesion was present in 3 out of 4 patients. All lesions were isointense or hypointense on the T1-weighted images relative to gray matter and showed homogeneous enhancement. One lesion was centered in the central gray matter, one lesion was centered within a cerebral hemisphere, one lesion was in optic nerve, and there were 2 parasellar lesions. CNS lymphoma has a variable appearance in children. Knowledge of risk factors in children may help in the early recognition of disease, allowing for timely intervention. This may prompt early biopsy or a conservative management in the appropriate clinical setting.

Lymphomatosis cerebri as a cause of white matter dementia

Primary central nervous system lymphoma most often presents as a solitary, isolated lesion in immunocompetent patients. Rarely, the disease presents as a diffuse, infiltrating condition without formation of a cohesive mass, a pattern called lymphomatosis cerebri. We present 3 immunocompetent individuals who developed rapidly progressive dementia. Magnetic resonance imaging features mimicked other disorders of white matter and prompted preoperative diagnoses of Binswanger's disease (subcortical ischemic vascular dementia), unknown leukoencephalopathy, viral infection, or infiltrating glioma. Neuropathologic examination at biopsy (Poon T, Matoso I, Tchertkoff V, Weitzner I Jr, Gade M. CT features of primary cerebral lymphoma in AIDS and non-AIDS patients. J Comput Assist Tomogr . 1989;13:6-9) and autopsy (Schwaighofer BW, Hesselink JR, Press GA, Wolf RL, Healy ME, Berthoty DP. Primary intracranial CNS lymphoma: MR manifestations. Am J Neuroradiol . 1993;10:725-9) demonstrated nonnecrotic, diffusely infiltrating, large-cell B-cell lymphoma of white matter, with relative sparing of gray matter, and without significant leptomeningeal involvement or bulky periventricular disease at autopsy. Microglial and astrocytic reactions, but only subtle myelin pallor, were evident as individual tumor cells permeated the entire brain and spinal cord, albeit with considerable variation in cell density. Individual tumor cells could be identified from the optic nerve to spinal cord, documenting the "whole-brain" nature of the disease. CD20 immunostaining was necessary to fully appreciate the extent of individual lymphoma cell percolation through the white matter. The neurobehavioral deficits manifested by these patients demonstrate that lymphomatosis cerebri is an additional neoplastic cause of white matter dementia and can be added to the growing list of disorders responsible for this syndrome.

Therapeutic management of primary CNS lymphoma in immunocompetent patients

The best therapeutic management in primary CNS lymphomas remains to be defined because of the small size and short follow-up of retrospective series, the methodological pitfalls and limited number of prospective studies, and the paucity of randomized trials. The purpose of this article is to analyze, discuss and summarize the current therapeutic approaches, namely chemotherapy or radiotherapy as exclusive treatment, combined treatment, most commonly used drugs, intrathecal chemotherapy and consolidation radiotherapy and to provide recommendations for ordinary clinical practice. Some important therapeutic issues such as the management of intraocular lymphomas, elderly patients and patients without histological diagnosis, as well as the relevance of salvage therapy as a playground for the evaluation of new drugs are also analyzed. Finally, the main open questions as well as current and expected investigation trends are discussed.

Primary CNS lymphoma: clinical presentation, pathological classification, molecular pathogenesis and treatment

Primary CNS lymphomas (PCNSL) represent malignant non-Hodgkin's B cell lymphomas, which are confined to the central nervous system. They show a dramatic increase in frequency in the immunocompromised as well as in the immunocompetent population. Recent studies have identified germinal center B cells as the cellular origin of PCNSL; however, the details of their molecular pathogenesis still remain to be elucidated. Treatment recommendations are not clearly established. Radiotherapy (RT) is efficient in terms of tumor response, but not curative. Median survival after RT alone is about 1 year. According to the results of uncontrolled studies the combination of RT and chemotherapy based on high-dose methotrexate (HD-MTX) is most efficient in terms of survival rates. However, long-term neurotoxicity overshadows treatment efficacy, especially in patients over 60 years of age. The authors favor the systematic evaluation of chemotherapy alone with protocols including HD MTX, because unicenter results are promising in terms of both survival as well as quality of life in long term survivors.

Prevention of recurrence and prolonged survival in primary central nervous system lymphoma (PCNSL) patients treated with adjuvant high-dose methylprednisolone

Five patients at risk for primary central nervous system lymphoma (PCNSL) recurrence were treated with high-dose methylprednisolone (HDMP) to prevent 'trafficking' of malignant lymphocytes into the central nervous system (CNS). HDMP was chosen because of its ability to stabilize the 'blood brain barrier (BBB)'. Three men with newly diagnosed PCNSL, ages 62, 76 and 78y, whose survival was projected to be 6.6 months, began treatment after achieving complete response (CR) to initial radiation therapy alone and survived 27, 37 and 59 months after treatment. In none was death from recurrent disease in CNS but one patient did die of systemic non-Hodgkin's lymphoma (NHL) five years after PCNSL diagnosis. A 20 y old man was treated with HDMP after successful combined modality therapy and is alive 75+ months after initial diagnosis without evidence of disease recurrence. A 34 y old man relapsed after combined modality initial treatment and failed to respond to HDMP when treatment was begun after unsuccessful salvage therapy; he died of disease 12 months after initial diagnosis. There were no treatment complications. The promising results in this pilot study from the basis for a North Central Cancer Treatment Group (NCCTG) 96-73-51, a Phase 2 clinical trial of brain radiotherapy and HDMP for PCNSL patients 70y of age and older, a group of patients at high risk for toxicity from intensive combined modality therapy.

Primary central nervous system lymphoma: from clinical presentation to diagnosis

Immunocompetent patients with primary central nervous system lymphoma (PCNSL) present with a median age of 55 years, immunosuppressed patients with a median age of 40 years. They show a broad range of signs and symptoms. Symptoms of increased intracranial pressure and personality change are most frequent, followed in frequency by ataxia and hemiparesis. The median time from onset of symptoms to diagnosis is 3-5 months in immunocompetent patients and 2 months in immunodeficient patients. The time to diagnosis can be considerably longer in patients with slowly developing personality change or fluctuating symptoms due to spontaneous or steroid-induced remission of so-called sentinel lesions. Native CT scans show iso- or hyperdense lesions with homogenous contrast enhancement. T1-weighted MRI scans show hypointense and T2-weighted scans hyperintense lesions. The definitive diagnosis of PCNSL requires biopsy. In some cases, however, the definitive diagnosis may exclusively be made by the demonstration of malignant B-lymphocytes in the cerebrospinal fluid.

Cerebral neoplasms in adults

MRI plays a critical role in the diagnosis, management, and follow-up of adult supratentorial neoplasms. However, there is considerable overlap in the imaging findings of these lesions. New imaging methods, such as functional MRI, diffusion imaging, and spectroscopy may further improve diagnostic specificity and surgical management. Knowledge of the pathogenesis of these tumors, imaging characteristics, and available novel imaging tools will aid the radiologist in making meaningful contributions in the evaluation and treatment of these lesions.

Perfusion-sensitive MRI of cerebral lymphomas: a preliminary report

PURPOSE

To date, there have been no systematic reports examining cerebral lymphomas with perfusion-sensitive MRI. We sought to determine the characteristics of perfusion-sensitive MRI of these tumors.

METHOD

Five primary and three secondary cerebral lymphomas were analyzed. None of the patients had a history of AIDS. Various areas of relative cerebral blood volume (rCBV) within tumor were analyzed, and maximum CBV ratios (CBV[tumor/contralateral]) were identified for evaluation.

RESULTS

In three primary and three secondary cerebral lymphomas, maximum CBV ratios were <2.5 (mean 1.50). In others, maximum CBV ratios were markedly higher than those of the white matter (5.38 and 5.42). Mean maximum rCBV ratios of primary and secondary cerebral lymphomas were 2.93 and 1.43, respectively. There was no significant difference between the two groups.

CONCLUSION

Cerebral lymphomas had a tendency to have low rCBV values. This information may be helpful in diagnosing these tumors.

Characterization of primary intracranial lymphoma by computed tomography: an analysis of 36 cases and a review of the literature with particular reference to calcification haemorrhage and cyst formation

Previous published series describing the appearances of primary central nervous system lymphoma (PCNSL) state that calcification, haemorrhage and cyst formation are rare, but generally fail to quantify or expand on this statement. We present the pre-treatment computed tomography (CT) findings of 36 patients with biopsy proven PCNSL. In this series, calcification was present in only one very atypical lesion and evidence of haemorrhage was not seen. Small intralesional cysts were present in four of the total of 50 lesions. PCNSL usually appeared as one or more well defined focal lesions, iso- or hyperdense to grey matter, with homogeneous enhancement following IV contrast injection. Less commonly the contrast enhancement was inhomogeneous, only one lesion failed to enhance. Disproportionately little oedema and mass effect compared with lesion size was noted on approximately half the CTs. Lesions usually touch either the ependymal lining of the ventricles or the leptomeningeal surface.

An instructive false diagnosis: steroid-induced complete remission of a CNS tumor--probably lymphoma

In recent years the incidence of primary cerebral lymphomas has increased. Diagnosis by imaging techniques (CCT, angiography, MRT) and stereotactic biopsy are considered as reliable diagnostic tools. Therapeutically a combination of radio-, steroid- and chemotherapy is recommended. We report a case of space-occupying CNS lesion in which the radiopaque enhancing process completely disappeared after biopsy and steroid therapy. A year later the tumor recurred on the other side and again regressed after steroid therapy. The first biopsy showed signs of a papillar tumor, so a choroid plexus papilloma was suspected. On examination of the treatment history, however, this diagnosis had to be revised. A primary CNS lymphoma seems most probable. The phenomenon of a tumor remission under steroid administration and the problems related to the differential diagnosis are discussed.

Primary lymphoma of the internal auditory canal. Case report and review of the literature

We report a rare case of a primary intracranial B cell lymphoma originating in the internal auditory canal. The clinical manifestations were indistinguishable from those of other, more common tumors of the same region. We achieved total gross tumor removal with preservation of the facial nerve. A detailed histologic examination and a systemic workup confirmed the primary nature of this tumor. To our knowledge, this is the second case reported in the literature of a primary malignant lymphoma originating in the internal auditory canal. This is the first instance that includes immunohistochemical and cytometric studies of fresh tissue. We discuss the management of primary lymphomas of the central nervous system, with special emphasis on their association with acquired immunodeficiency syndrome and other immune system diseases. Awareness of primary central nervous system lymphomas is important, since a greater occurrence of these rare tumors in the cerebellopontine angle is probable in the future.

Toxoplasma encephalitis in a HIV patient: unusual involvement of the corpus callosum

In patients with acquired immuno-deficiency syndrome, the differential diagnosis between primary brain lymphoma and toxoplasma encephalitis is not radiologically always straightforward, especially in the presence of a solitary cerebral lesion. In this context, involvement of the corpus callosum is almost exclusively associated with primary brain lymphoma. We describe here an HIV-infected patient who presented with a single and large cerebral lesion affecting the corpus callosum, suggestive of primary brain lymphoma on MRI-scan but who nonetheless responded clinically and radiologically to an anti-toxoplasma drug trial confirming the diagnosis of toxoplasma encephalitis.

Primary Ki-1-positive T-cell lymphoma of the brain--an aggressive subtype of lymphoma: case report and review of the literature

BACKGROUND

By detection of the Ki-1 antigen, Stein (1985) defined a new entity of anaplastic large cell lymphoma [24]. Apart from our case, only four further cases of Ki-1 positive primary central nervous system lymphoma (PCNSL) have been reported in the literature to date.

CASE REPORT

A 63-year-old man presented with two frontal and parietal mass lesions and one ring lesion on computed tomography scan. Clinically, no evidence of brain metastases or abscesses could be found. Immunohistochemical investigations of biopsy specimens revealed a large cell anaplastic T-cell lymphoma positive to Ki-1 antigen. In spite of all therapeutic efforts, the patient died less than 3 months after the onset of symptoms.

DISCUSSION

In all cases the clinical course was very rapid, suggesting that Ki-1 positive PCNSL might form an aggressive subtype of lymphomas. Since the radiologic appearance was atypical and clinical diagnosis was not possible, diagnostic biopsy for immunohistochemical diagnosis should be performed.

Nonenhancing primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is rare, although its frequency has increased in recent years. Radiographically, almost all PCNSL enhance on CT and/or MRI, and nonenhancing PCNSL has been thought to be extremely rare. We present PCNSL showing multiple nonenhancing lesions on MRI in an immunocompetent patient.

Leptomeningeal tumor in primary central nervous system lymphoma: recognition, significance, and implications

The true incidence of leptomeningeal tumor in primary central nervous system lymphoma is unknown. We studied prospectively the cerebrospinal fluid profile of 96 patients without acquired immunodeficiency syndrome but with primary central nervous system lymphoma at diagnosis, at completion of treatment, and at recurrence. Magnetic resonance images and pathology slides were examined for evidence of leptomeningeal tumor. Leptomeningeal tumor was diagnosed by (1) positive findings on cerebrospinal fluid cytology, (2) leptomeningeal or subependymal enhancement on magnetic resonance imaging, or (3) pathological evidence of leptomeningeal tumor. We recorded whether treatment directed against the leptomeninges was given. Cerebrospinal fluid was examined in 86 of 96 patients at diagnosis and 29 of 42 at recurrence. The incidence of leptomeningeal tumor was 42% at diagnosis and 41% at recurrence. Only elevated levels of protein and lactate dehydrogenase isoenzyme-5 were significantly associated with leptomeningeal tumor (p = 0.012, p = 0.016, respectively). Treatment against the leptomeninges was significantly associated with the probability of achieving a complete response and a longer freedom from relapse. Patients older than 50 years had a worse disease-specific survival but a similar probability of responding to therapy as younger patients. Our data show that leptomeningeal tumor in primary central nervous system lymphoma is more prevalent than originally thought, and indicate the need for therapy inclusive of the leptomeninges in all patients.

Occult systemic non-Hodgkin's lymphoma (NHL) in patients initially diagnosed as primary central nervous system lymphoma (PCNSL): how much staging is enough?

OBJECTIVE

To demonstrate the extent of staging necessary to exclude occult systemic stage IV NHL before making a diagnosis of stage I AE PCNSL.

BACKGROUND

The diagnosis of PCNSL requires the demonstration of malignant lymphocytes within the CNS (usually by biopsy) and finding no evidence of systemic NHL. Different staging approaches have been recommended, ranging from extensive systemic evaluation (including bone marrow examination) to a more focused approach (abdominal and pelvic CT) to no systemic evaluation. We have employed a staging regimen that included: ophthalmologic evaluation (including slit lamp examination); CT of chest, abdomen, and pelvis; bilateral iliac crest aspirate and biopsy; flow cytometry of circulating lymphocytes; and, in men, testicular ultrasound.

DESIGN/METHODS

We carried out a retrospective review of 128 patients entered into the Mayo Lymphoma Project data bank (1975-1994).

RESULTS

Between the years 1975 and 1994, five patients (3.9%) were identified who fulfilled criteria for the diagnosis of PCNSL (typical clinical history, pathognomonic neuro-imaging, and histologic proof of NHL in brain tissue) but who had occult systemic NHL on staging (bone marrow 1, abdominal lymph nodes 3), or at autopsy (colon 1). Case histories are presented.

CONCLUSIONS

Patients with apparent PCNSL may have systemic NHL. Complete staging is essential to the initial management of patients presenting as PCNSL to exclude systemic stage IV disease.

Primary brain lymphoma. A brief review of clinical aspects and management

Primary C.N.S. lymphoma is a rare tumor. Five such cases were treated in our clinic between January, 1991, and October, 1993. Four patients had tumor decompression and one had total resection. All of them received radiotherapy (radiation dose 40 Gy) and chemotherapy. One patient expired during the immediate postoperative period. Four patients showed a disappearance of the tumor on CT scan after the complete course of therapy of 9 months. Three patients showed recurrence intracranially at 15, 12, and 10 months. All patients died during follow up except one, who has been alive without recurrence for 10 months. Median survival was 13 months.

Intraocular lymphoma presenting as retinal vasculitis

We describe two unusual young patients with intraocular lymphoma who presented clinically with "retinal vasculitis." Brain biopsy specimens in both showed an angiocentric pattern of lymphocytic infiltration. Immunohistochemical studies were positive for T-cell markers. Both the retinal and the brain blood vessels were thus a preferential site of appearance of the malignant T-cells. Both cases responded favorably to aggressive chemotherapy with long-term survival. In the world's literature, there are 57 cases of intraocular lymphoma in which cell surface-marker studies were performed; of these, 53% proved to be B-cell lymphomas and 21% to be T-cell lymphomas. As more cases of intraocular lymphoma are studied with cell-typing and as our histochemical techniques improve, a correlation between the systemic and ocular findings and the cell type may be revealed.

Radiotherapy of primary central nervous system lymphoma in patients with and without human immunodeficiency virus. Ten years of treatment experience at the University of California San Francisco

BACKGROUND

Classic human immunodeficiency virus (HIV) negative primary central nervous system lymphoma (PCNSL) is a relatively uncommon occurrence, whereas the incidence of HIV positive PCNSL has increased dramatically during the past 5 years. Between 2% and 6% of all patients with acquired immune deficiency syndrome (AIDS) will have PCNSL develop clinically, and as many as 11% will have PCNSL found at autopsy. In the United States, some of the earliest and most extensive experience with HIV positive PCNSL has occurred in San Francisco. This article reports on PCNSL in patients with and without HIV.

METHODS

Using our diagnosis-based computer retrieval system, we identified all patients treated with radiotherapy for PCNSL between January 1982 and January 1992 and reviewed their medical records. Population characteristics, risk factors and length of survival (LOS), were analyzed. Statistical methodology included the Cox proportional hazards model and Kaplan-Meier survival curves.

RESULTS

Fifty-six patients were identified with PCNSL, of which 41 were HIV positive and 15 were HIV negative. There was a fourfold increase in the total number of PCNSL cases during the time period 1987-1991 as compared with the preceding 5 years; these cases primarily were in the HIV positive group. The average Karnofsky performance score (KPS) in the HIV positive group was 50, whereas in the HIV negative group, the KPS was 35. However, the median LOS in the HIV positive group was 3 months, whereas in the HIV negative group it was 20 months. Within each group, there was a statistically significant correlation between KPS and LOS.

CONCLUSIONS

Patients with HIV and PCNSL have a much shorter median LOS than do patients with PCNSL but without HIV; however, the outcome for both groups is dismal. Randomized clinical trials are needed to determine which patients with HIV might benefit from more aggressive therapy and to determine the optimal choice and dosages of chemoradiation therapy for patients with PCNSL without HIV.

Review article: computed tomography and magnetic resonance in the diagnosis of intraventricular cerebral masses

We describe a series of 60 cases of patients with masses arising within the cerebral ventricles. The site and relative frequency is noted for each histological type. The differential diagnosis depends on patient age and sex, site, morphology and number of masses, presence and type of hydrocephalus and the characteristics of the mass on computed tomography (CT) and magnetic resonance (MR) images. A review of the literature has been performed and this information collated with our own experience to give detailed descriptions of the typical features of each intraventricular mass. Attention is drawn to intraventricular neurocytoma, a recently described tumour that may be mistaken histologically for intraventricular oligodendroglioma or ependymoma. A comparison is made of the value of CT and MR in the diagnosis of intraventricular masses.

Primary central nervous system lymphoma in Japan--a retrospective, co-operative study by CNS-Lymphoma Study Group in Japan

This manuscript reports the results of the first cooperative study on primary central nervous system lymphoma (PCNSL) in Japan. Of 196 patients registered, 170 were judged as having PCNSL. No patients were immunocompromised. Of the 170 patients with PCNSL, 93 were males and 77 were females. The mean was 56.7 years. One hundred and nineteen tumors were confirmed histopathologically, and 51 were diagnosed by neuroimaging alone. All the tumors were non-Hodgkin's lymphoma. According to the Working Formulation for Clinical Usage (WF), 96 out of 119 tumors were classifiable: 53 were diffuse large cell type (55.2%), 17 immunoblastic type (17.7%), 9 diffuse small cleaved type (9.4%), 6 diffuse mixed type (6.3%), 5 polymorphous type (5.2%), 5 small lymphocytic type (5.2%) and 1 small non-cleaved type (1.0%). Of 21 tumors studied immunohistochemically, 18 were B-cell type and 3 were T-cell type. Irradiated patients (144) survived significantly longer than non-irradiated patients, (median survival time, MST: 19.2 and 2.7 months, respectively; p < 0.001). There was a remarkable difference in survival among patients of the intermediate lymphomas; MST (18 months) of patients with large cell lymphoma was significantly shorter than MST (over 96 months) of patients with other intermediate grade lymphomas (small cleaved and mixed) (p < 0.001) and had no significant difference from MST (9 months) of patients with high grade lymphomas. If patients were irradiated with more than 40 Gy, higher doses and different modes of irradiation brought no further survival advantage. Chemotherapy was performed in 87 of 144 irradiated patients (60.4%). No regimens were effective in prolonging survival. Of 144 irradiated patients, a complete or partial response to initial treatment was demonstrated in 91 (63.2%) and 43 patients (29.9%), respectively. Improvement in performance status was confirmed in 82 patients (57.0%). Despite a good response to initial treatments, 88 out of 144 evaluatble patients have died of PCNSL (MST: 19 months). Multivariate analysis based on the Cox hazard model revealed that histology of tumor, age at onset, performance status, and radiotherapy were prognostic factors. Neither chemotherapy nor mode of surgery was a beneficial factor.

Cerebellar T-cell lymphoma: an unusual primary intracranial neoplasm

Primary T-cell lymphoma within the central nervous system is extremely rare. Imaging characteristics appear indistinguishable from the more common B-cell lymphoma. A case of such a primary tumor is discussed and the MRI and CT findings presented.

Primary cerebral lymphoma: report of 24 patients and review of the literature

A retrospective study of 24 patients with primary non-Hodgkin's cerebral lymphoma (non-immunocompromised) is presented. All patients were seen at the Royal Preston Hospital, Lancashire between 1976 and 1991. Fifteen patients were over the age of 50 years (range 27-84). The commonest clinical presentation, seen in 16 patients was of an expanding space-occupying lesion. The diagnosis was suspected from the radiological findings but confirmation in every case was by histological examination of biopsy or necropsy material. The tumours were treated either by surgical excision or by biopsy and radiotherapy. Chemotherapy was given in two patients. Despite these measures the mean survival time was 3.6 months. The clinical radiological and pathological features of these tumours are highlighted with particular emphasis on the use of stereotactic biopsy, immunohistochemistry and chemotherapy in diagnosis and treatment.

Primary central nervous system lymphomas--an update

Primary CNS lymphomas (PCNSL), until recently representing about 1% of all brain tumors, show dramatically increased incidence both in high-risk groups (immunocompromised, AIDS) and in the general population. They are extranodal diffuse non-Hodgkin's lymphomas, the morphology and classification of which are identical to those of systemic lymphomas, although PCNSL show different biological behavior and diagnosis according to the New Working Formulation and updated Kiel classification may be difficult. The majority are large B cell variants of high-grade malignancy; low-grade subtypes and T cell lymphomas are rare. Sixty per cent occur in the supratentorial space (hemispheres, periventricular) and 12% in the posterior fossa; 30% are multiple (50%-70% in AIDS). PCNSL show a male preponderance with a peak incidence in the 5th-7th decade (3rd-4th in AIDS). The duration of diffuse or focal clinical symptoms averages 1-2 months. Computed tomography and magnetic resonance imaging scans show single or multiple or diffuse, often typical lesions. Diagnosis is achieved by evaluation of stereotactic biopsy material or cerebrospinal fluid cytology using immunocytological markers. Current therapy in immunocompetent patients, radiation plus corticosteroids and pre- or postradiation polychemotherapy, shows response rates of 85% with a median survival of 17-44 months, a prognosis similar to that for glioblastoma. Meningeal PCNSL is treated with intrathecal methotrexate or cytosine arabinoside. Transliquoral seeding of PCNSL is frequent, distant metastases occurring in 6%-8%. Therapy of AIDS-related PCNSL makes use of radiation and corticosteroids, and rarely of chemotherapy. The pathogenesis of PCNSL is unknown, but Epstein-Barr virus may be a contributory factor.