Primary Central Nervous System Lymphoma (PCNSL) is a rare neoplasm that can involve brain, eye, leptomeninges, and rarely spinal cord. PCNSL lesions most typically enhance homogeneously on T1-weighted magnetic resonance imaging (MRI) and appear T2-hypointense, but high variability in MRI features is commonly encountered. Neurological symptoms and MRI findings may mimic high grade gliomas (HGGs), tumefactive demyelinating lesions (TDLs), or infectious and granulomatous diseases. Advanced MRI techniques (MR diffusion, spectroscopy, and perfusion) and metabolic imaging, such as Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) or amino acid PET (usually employing methionine), may be useful in distinguishing these different entities and monitoring the disease course. Moreover, emerging data suggest a role for cerebrospinal fluid (CSF) markers in predicting prognosis and response to treatments. In this review, we will address the challenges in PCNSL diagnosis, assessment of response to treatments, and evaluation of potential neurotoxicity related to chemotherapy and radiotherapy.

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Primary CNS Lymphomas: Challenges in Diagnosis and Monitoring

Although primary diffuse large B-cell lymphomas of the CNS are designated as primary CNS lymphomas according to the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissue in 2008, a variety of other lymphomas (Burkitt lymphomas, EBV-positive diffuse large B-cell lymphoma of the elderly) and related diseases (lymphomatoid granulomatosis) that are also found in the CNS have been spotlighted in recent years. The histopathology of primary CNS Burkitt lymphomas mimics that of primary diffuse large B-cell lymphomas of the CNS after steroid administration. Therefore, for correct diagnosis of the involved lymphoma, comprehensive fluorescent in situ hybridization analysis for c-MYC and BCL2 is recommended in all primary CNS lymphoma cases with aggressive clinical course, multifocal involvement of the CNS, and a high proliferation index. The pathological characteristics of primary CNS EBV-positive diffuse large B-cell lymphoma of the elderly have similarities with those of the latency phenotype III, EBV lymphoproliferative disorders that arise in the setting of immunodeficiency. These age-related lymphomas usually occur in elderly immunocompetent patients, and the incidence of this disease was estimated to range from 4.0% to 13.6% of all primary CNS lymphomas. Shorter overall survival has been reported for patients with this disease. Lymphomatoid granulomatosis (LYG) is a systemic, EBV-driven, angiocentric and angiodestructive lymphoproliferative disorder. Primary LYG that shows distinct clinicopathological features compared with systemic LYG was recently reported. Finally, this review focuses on the relationship between primary CNS lymphomas and demyelinating diseases, and the concomitant use of intraoperative cytology and frozen sections that are helpful in rapid intraoperative diagnosis.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/neup.12276

Primary central nervous system lymphomas and related diseases: Pathological characteristics and discussion of the differential diagnosis.

Pancreatic tuberculosis is very rare, but recently, there has been a spurt in the number of reports on pancreatic involvement by tuberculosis. It closely mimics pancreatic cancer, and before the advent of better imaging modalities it was often detected as a histological surprise in patients resected for a presumed pancreatic malignancy. The usual presentation involves abdominal pain, loss of appetite and weight, jaundice which can be associated with cholestasis, fever and night sweats, palpable abdominal lump, and peripheral lymphadenopathy. Computed tomography (CT) of the abdomen is an important tool for evaluation of patients with pancreatic tuberculosis. This CT imaging yields valuable information about the size and nature of tubercular lesions along with the presence of ascites and lymphadenopathy. However, there are no distinctive features on CT that distinguish it from pancreatic carcinoma. Endoscopic ultrasound provides high resolution images of the pancreatic lesions as well as an opportunity to sample these lesions for cytological confirmation. The presence of granulomas is the most common finding on histological/cytological examination with the presence of acid fast bacilli being observed only in minority of patients. As there are no randomized or comparative studies on treatment of pancreatic tuberculosis it is usually treated like other forms of tuberculosis. Excellent cure rates are reported with standard anti tubercular therapy given for 6–12 months.

Pancreatic tuberculosis: Pancreatic tuberculosis

OBJECTIVE. This study intended to investigate the usefulness of histogram analysis of apparent diffusion coefficient (ADC) maps for discriminating primary CNS lymphomas (PCNSLs), especially atypical PCNSLs, from tumefactive demyelinating lesions (TDLs). MATERIALS AND METHODS. Forty-seven patients with PCNSLs and 18 with TDLs were enrolled in our study. Hyperintense lesions seen on T2-weighted images were defined as ROIs after ADC maps were registered to the corresponding T2-weighted image. ADC histograms were calculated from the ROIs containing the entire lesion on every section and on a voxel-by-voxel basis. The ADC histogram parameters were compared among all PCNSLs and TDLs as well as between the subgroup of atypical PCNSLs and TDLs. ROC curves were constructed to evaluate the diagnostic performance of the histogram parameters and to determine the optimum thresholds. RESULTS. The differences between the PCNSLs and TDLs were found in the minimum ADC values (ADCmin) and in the 5th and 10th percentiles (A...

https://www.ajronline.org/doi/pdf/10.2214/AJR.14.12677

Histogram analysis of apparent diffusion coefficient maps for differentiating primary CNS lymphomas from tumefactive demyelinating lesions.

The basal ganglia and thalami are paired deep grey matter structures with extensive metabolic activity that renders them susceptible to injury by various diseases. Most pathological processes lead to bilateral lesions, which may be symmetric or asymmetric, frequently showing characteristic patterns on imaging studies. In this comprehensive pictorial review, the most common and/or typical genetic, acquired metabolic/toxic, infectious, inflammatory, vascular and neoplastic pathologies affecting the central grey matter are subdivided according to the preferential location of the lesions: in the basal ganglia, in the thalami or both. The characteristic imaging findings are described with emphasis on the differential diagnosis and clinical context.

/pdf/bilateral-lesions-of-the-basal-ganglia-and-thalami-central-1reib3v11o.pdf

Bilateral lesions of the basal ganglia and thalami (central grey matter)-pictorial review.

Primary central nervous system lymphoma (PCNSL) is an uncommon but important variant of non-Hodgkin lymphoma and represents up to 6% of all primary central nervous system (CNS) malignancies. Recognition of this entity by radiologist on MRI may avoid unnecessary neurosurgical resection and redirect to biopsy. The pretreatment MRI of patients with biopsy proven PCNSL from the last 5 years at our institution was reviewed. Selected examples were used to construct a pictorial essay to illustrate some of the typical and atypical MR features of PCNSL. MRI of other CNS conditions with imaging similarities to PCNSL was included to demonstrate possible mimics. The typical features of PCNSL lymphoma are intra-axial homogenous single or multiple contrast enhancing lesions, with marked surrounding oedema and restricted diffusion, usually contacting a cerebrospinal fluid (CSF) surface. Necrosis, peripheral enhancement, haemorrhage or calcification are unusual and other diagnoses should be considered if any of these features are present. Potential mimics include high grade glioma, infarcts, metastatic disease, demyelination, abscess and secondary lymphoma. Careful assessment of the MR features and correlation with the clinical findings should enable the radiologists to raise the possibility of PCNSL and minimise the risk of unnecessary resection.

Magnetic resonance features of primary central nervous system lymphoma in the immunocompetent patient: a pictorial essay.

Introduction: To define the features of primary central nervous system lymphoma (PCNSL) on MRI in immunocompetent patients.



Methods: A retrospective review of the authors' institutional database was performed to identify histologically proven cases of PCNSL. Images were retrieved and reviewed with respect to location, lesion number, size, signal intensity, enhancement characteristics, oedema and necrosis.



Results: Thirty-one cases of histologically proven PCNSL had available imaging. One patient was excluded due to immunosuppression. Of the 30 remaining cases, the average age was 65.5 years, and males and females were equally represented. A total of 68 lesions (average of 2.5 per patient) were identified. With diffusion-weighted imaging, all but two had restricted diffusion (40.3% mild and 55.6% marked) and all but one had enhancement (51.5% homogeneous, 42.6% heterogeneous and ring 4.4%). Most lesions were isointense to grey matter (75.8% on T2-weighted image (WI) and 82.5% on T1-WI). Oedema was mild in 43.4% and marked in 55.2%. Necrosis was seen in only five lesions (7.4%). On a per patient basis, 50% had bilateral lesions and 96.7% had lesions contacting a cerebrospinal fluid (CSF) surface. 16.7% of patients had posterior fossa involvement and 30% had lesions in the basal ganglia or thalami.



Conclusion: The vast majority of cases of PCNSL in immunocompetent patients have lesions contacting a CSF surface, enhancement and restricted diffusion with no necrosis. These features should alert radiologists to the diagnosis of PCNSL.

Primary central nervous system lymphoma in immunocompetent patients: A retrospective review of MRI features

A 26-year-old male student from southern India presented to the emergency department with a 1-week history of epigastric pain, jaundice, fever, and weight loss. His liver function tests showed a cholestatic pattern with a bilirubin level of 35 μmol /L (normal, <20 μmol /L), an alkaline phosphatase level of 585 U/L (normal, 50–130 U/L), and a γ-glutamyl transferase level of 256 U/L (normal, 10–49 U/L). His Creactive protein level and erythrocyte sedimentation rate were mildly elevated, at 22 mg/L (normal, < 10 mg/L) and 48 mm/h (normal 0–10 mm/h), respectively. The full blood examination was unremarkable, and the coagulation profile was normal. Hepatitis B and C and human immunodeficiency virus serologic results were negative. Liver sonography (Figure 1, A and B) indicated intrahepatic duct dilatation and the presence of a lobulated hypoechoic mass (4.5 × 3.5 × 3.5 cm) inseparable from the posterior aspect of the head of the pancreas, possibly representative of a conglomerate of lymph nodes. Computed tomography (CT) showed an infiltrative soft tissue mass at the porta hepatis extending inferiorly to become inseparable from the posterior aspect of the pancreatic head. Portal vein thrombosis was noted with evidence of cavernous transformation (Figure 1, C and D). There were no other features of malignancy in the abdomen or pelvis. Endoscopy for dark rectal bleeding identified esophageal varices, gastritis, and duodenitis, consistent with portal hypertension secondary to portal vein obstruction. Colonoscopy indicated a normal colon and rectum. Chest CT revealed no evidence of pulmonary

https://onlinelibrary.wiley.com/doi/pdf/10.7863/jum.2011.30.11.1599

Elaine Liew

Papers

Magnetic resonance features of primary central nervous system lymphoma in the immunocompetent patient: a pictorial essay.

Primary central nervous system lymphoma in immunocompetent patients: A retrospective review of MRI features

Isolated periportal tuberculosis causing portal vein thrombosis.