Methionine-PET to differentiate between brain lesions appearing similar on conventional CT/MRI scans

BACKGROUND AND PURPOSE

11 C-Methionine (MET)-PET is a useful tool in neuro-oncology. This study aimed to examine whether a combination of diagnostic variables associated with MET uptake could help distinguish between brain lesions that are often difficult to discriminate in conventional CT and MRI.

METHODS

MET-PET was assessed in 129 patients with glioblastoma multiforme, primary central nervous lymphoma, metastatic brain tumor, tumefactive multiple sclerosis, or radiation necrosis. The accuracy of the differential diagnosis was analyzed using five diagnostic characteristics in combination: higher maximum standardized uptake value (SUV) of MET in the lesion/the mean normal cortical SUV of MET ratio, overextension beyond gadolinium, peripheral pattern indicating abundant MET accumulation in the peripheral region, central pattern denoting abundant MET accumulation in the central region, and dynamic-up suggesting increased MET accumulation during dynamic study. The analysis was conducted on sets of two of the five brain lesions.

RESULTS

Significant differences in the five diagnostic traits were observed among the five brain lesions, and differential diagnosis could be achieved by combining these diagnostic features. The area under the curve between each set of two of the five brain lesions using MET-PET features ranged from .85 to 1.0.

CONCLUSIONS

According to the findings, combining the five diagnostic criteria could help with the differential diagnosis of the five brain lesions. MET-PET is an auxiliary diagnostic technique that could help in distinguishing these five brain lesions.

Primary Central Nervous System Post-transplant Lymphoproliferative Disorder Misdiagnosed as Glioblastoma: A Case Report

BACKGROUND/AIM

Post-transplant lymphoproliferative disorder (PTLD) is a heterogeneous lymphoid cell disorder that occurs after solid organ and hematopoietic stem cell transplantation. Primary occurrence in the central nervous system PTLD (PCNS PTLD) is rare. We present a rare case of PCNS-PTLD misdiagnosed as glioblastoma (GBM).

CASE REPORT

A 62-year-old man underwent living-related kidney transplantation at the age of 49. He was introduced to our Department because of transient speech disturbance. Computed tomography scan of the head showed a mass at the right frontal lobe. Magnetic resonance imaging (MRI) of the head showed a ring-enhancing lesion with a small, homonymous enhanced lesion in the right frontal lobe, invading the corpus callosum. Because the pathological analysis of an intraoperative frozen section of the tumour indicated high-grade glioma, the tumour was completely resected and BCNU wafers were implanted at the resection site. However, postoperative pathological analysis indicated a diffuse large, CD20 positive B-cell lymphoma. In addition, the patient was positive for Epstein Barr virus-encoded small RNA, and therefore, diagnosis of PCNS PTLD was confirmed. The dose of the immunosuppressant therapy was reduced, and rituximab monotherapy was begun.

CONCLUSION

Both imaging and pathological findings on intraoperative frozen section of PCNS PTLD are similar to those of GBM. Therefore, in such cases, surgeons should consider PCNS-PTLD when the diagnosis indicates GBM.

Preparation and Characterization of Fe3O4@MTX Magnetic Nanoparticles for Thermochemotherapy of Primary Central Nervous System Lymphoma in vitro and in vivo

Background

Primary central nervous system lymphomas (PCNSL) are extranodal malignant non-Hodgkin lymphomas (NHL) that arise exclusively in central nervous system (CNS). Diffuse large B-cell lymphoma (DLBCL) is the most common histological subtype.

Purpose

To evaluate whether nano drug-loading system-mediated magnetic-targeted thermochemotherapy could produce a better therapeutic effect than single chemotherapy while reducing the use of chemotherapeutic drugs.

Methods

Six groups (control, Fe₃O₄, MTX, Fe₃O₄@MTX, Fe₃O₄ with hyperthermia and Fe₃O₄@MTX with hyperthermia) were set. Tumor cell apoptosis in each treatment group was detected by flow cytometry. Apoptosis-related gene expressions Caspase-3, Bax and Bcl-2 were detected by qPCR and Western blot; intracranial tumor model of PCNSL was established by intracranial injection of OCI-LY18 tumor cells into BALB/c-Nude mice. Magnetic resonance imaging (MRI) was used to monitor tumor progression and H&E staining was used to observe pathological changes of the tumor tissue.

Results

In vitro, compared with chemotherapy alone, apoptosis rate of Fe₃O₄@MTX mediated thermochemotherapy group was significantly increased, and expression of apoptosis-inducing gene Caspase-3 and Bax were significantly upregulated in OCI-LY18 cells, while expression of apoptosis-inhibiting Bcl-2 gene was significantly downregulated. In vivo, MRI showed successful generation of intracranial tumor, and tumor volume was significantly smaller in combined thermochemotherapy group than in single chemotherapy group. H&E staining result of tumor tissues in each group was consistent with MRI; tumor cells were significantly reduced in thermochemotherapy group. Expression of apoptosis-related gene Caspase-3 and Bax were significantly upregulated in tumor tissues, while expression of Bcl-2 gene was significantly downregulated.

Conclusion

These results demonstrated in vivo and in vitro that the combined thermochemotherapy of Fe₃O₄@MTX MNPs was superior to the single MTX chemotherapy with less dosage, which may promote apoptosis of DLBCL cells through the mitochondrial apoptotic pathway and provided a new way for the treatment of PCNSL.

B-scan ultrasound and cytology of the vitreous in primary central nervous system lymphoma with vitreoretinal involvement

AIM

To evaluate the diagnostic value of B-scan ultrasound and explore the cytological characteristics of patients with vitreoretinal lymphoma (VRL) and primary central nervous system lymphoma (PCNSL).

METHODS

The clinical data and pathologic specimens from patients with VRL diagnosed at the North Huashan Hospital from 2016 to 2017 were retrospectively reviewed. The patients were diagnosed by slit lamp ophthalmoscopy, B-scan ultrasound, cytology of the vitreous, which was obtained by vitrectomy, and cytokine measurements of interleukin (IL)-10 and IL-6.

RESULTS

Twenty-six eyes (19.4%) out of 134 eyes of 67 patients (47 men and 20 women) with PCNSL were diagnosed with VRL by B-scan ultrasound, and 14 eyes (10.4%) were diagnosed by slit lamp ophthalmoscopy. Twenty-four eyes (17.9%) of 17 patients were confirmed as having VRL with cytology. No difference in the association between intracranial lesion location and ocular involvement was found. VRL patients had higher levels of vitreous IL-10 and IL-10/IL-6 when compared with macular hole cases, but the difference was not statistically significant.

CONCLUSION

A total of 25.4% of the PCNSL patients had VRL, B-scan ultrasound examination had characteristic features and is recommended over slit lamp ophthalmoscopy for the screening diagnosis of PCNSL with intraocular involvement. Moreover, the cytological and immunohistochemical analyses performed after 25-gauge diagnostic vitrectomy were accurate diagnostic techniques.

Second malignancies in patients with primary central nervous system lymphoma

BACKGROUND

Primary central nervous system lymphoma (PCNSL) is a rare extranodal lymphoma with distinctive biological behaviors. The evolving treatment of PCNSL has greatly improved the outcome for patients with this disease and has stimulated interest in second malignancies (SMs) in patients diagnosed with PCNSL.

METHODS

The records of 129 cases of PCNSL at Mayo Clinic, diagnosed between January 1, 1988, and November 26, 2012, were reviewed. Data on clinical characteristics, laboratory parameters, treatments, outcomes, and SMs were collected. The mean follow-up time was 44.8 months (range, 0.5-240 months; median, 28.0 months).

RESULTS

Altogether, 28 cases with 30 (23.26%) SMs were identified. Twenty (15.50%) patients had prior or synchronous SM. Ten (7.76%) patients developed a subsequent primary cancer after PCNSL. The most common sites of prior or synchronous SMs were prostate (4/20), skin (4/20), and gastrointestinal (3/20). The most common site of the subsequent SM was skin (4/10). Two cases were identified with both prior SM and subsequent SM.

CONCLUSIONS

Second malignancies in cases with PCNSL were not uncommon and occurred in nearly a quarter of our cohort. Nonmelanoma skin cancers were frequently seen. Therefore, screening for SMs should also be considered in long-term follow-up of patients with PCNSL. In addition, the high incidence of subsequent cancer, synchronous cancer, and frequently seen nonmelanoma skin cancers may all indicate an immunosuppressed state in patients with PCNSL.

Correlation between positron emission tomography findings and glucose transporter 1, 3 and L-type amino acid transporter 1 mRNA expression in primary central nervous system lymphomas

Primary central nervous system lymphoma (PCNSL) is an aggressive form of non-Hodgkin lymphoma with a poor prognosis. [¹⁸F] 2-fluoro-2-deoxy-D-glucose (FDG) and L-(methyl-¹¹C)-methionine (MET) are the most widely used tracers in oncological positron emission tomography studies for PCNSL and commonly identify hypermetabolic lesions through increased uptake of FDG and MET. However, the mechanisms underlying the uptake of FDG and MET in PCNSL have not been clearly determined. The present study aimed to investigate the mRNA expression levels of glucose transporter (GLUT)1, GLUT3 and L-type amino acid transporter 1 (LAT1) in resected PCNSL specimens, in order to identify whether these transporters are associated with the increased uptake of FDG and MET. A total of 7 patients diagnosed with PCNSL were investigated. The uptake of FDG and MET by the tumors was evaluated based on the maximum standardized uptake value (SUVmax). The quantity of GLUT1, GLUT3 and LAT1 mRNA in the PCNSL specimens was measured to determine whether GLUT1, GLUT3 and/or LAT1 are involved in the increased uptake of FDG and MET in PCNSL. Furthermore, microvessel density (MVD) and cell density (CD) were measured in all the cases. Our results indicated that the expression of GLUT3, but not GLUT1, was significantly correlated with FDG SUVmax and the expression of LAT1 was significantly correlated with MET SUVmax. However, neither MVD nor CD were found to be significantly associated with the uptake of FDG and MET. GLUT3 was identified as a key determinant of FDG accumulation, whereas LAT1 was a key determinant of MET accumulation in PCNSL. Therefore, GLUT3 and LAT1 may represent potential targets for the future development of novel therapeutic agents for PCNSL.