FDG-PET scanning for detection and staging of extranodal marginal zone lymphomas of the MALT type: a report of 42 cases

A Case of Persistent Lung Masses After Treatment of Hodgkin Lymphoma

CASE PRESENTATION

The patient is a 49-year-old woman who had never used tobacco with a history of relapsing polychondritis and episcleritis. She sought treatment at our clinic for evaluation of multiple lung masses. She originally received a diagnosis by chest radiography performed to rule out sarcoidosis as the cause of episcleritis showing an abnormal findings. She had no contributory surgical, family, or social history. The autoimmune markers were notable for positive rheumatoid factor (153 IU/mL) and elevated erythrocyte sedimentation rate (97 mm/h) and C-reactive protein (65.5 mg/L). Pertinent studies with negative results included antineutrophilic cytoplasmic antibody, antinuclear antibody, cyclic citrullinated peptide antibody, Sjogren syndrome-related antigen A, and Sjogren syndrome-related antigen B tests.

Multimodality Appearances of Marginal Zone Lymphoma Masquerading as Cryptogenic Organizing Pneumonia-serial Chest Radiograph and High-resolution Computed Tomography Appearances: (18F) Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Staging Utility

Marginal zone lymphoma (MZL) is a group of low-grade, indolent, non-Hodgkin lymphomas rarely manifesting in the lungs. A 46-year-old man presenting with shortness of breath and cough was investigated and treated over 10 months for an atypical pattern of lung disease in keeping with cryptogenic organizing pneumonia (COP). Initial lung biopsies were nondiagnostic - repeat sampling eventually showed MZL. Staging whole-body (18F) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) demonstrated multisystem stage IV disease with intensely avid widespread pulmonary changes resembling COP. The case elegantly illustrates that pulmonary MZL can present insidiously masquerading as COP and shows the value of (18F) FDG PET/CT to stage extranodal MZL.

Perplexity of Preoperative Multimodal Investigations in a Case of Parotid MALToma

Mucosa-associated lymphoid tissue(MALT) lymphoma is a distinct subtype of lymphoma, presenting as a diffuse gland involvement or a discrete mass. Pre-operative diagnosis is a challenge as Fine Needle Aspiration Cytology is often inconclusive and presently no radiological investigation is confirmatory, therefore final diagnosis is made after surgical resection and immunohistopathology. We report a case of MALT lymphoma, which clinically presented as a unilateral large diffuse swelling of the parotid gland with a diagnostic dilemma eventually underwent total parotidectomy to be finally diagnosed as MALT lymphoma of parotid gland and received field radiotherapy with complete cure and no recurrence in a 2-year follow-up.

Enhancing prognostication and personalizing treatment of extranodal marginal zone lymphoma

INTRODUCTION

Extranodal marginal zone lymphoma (EMZL) of mucosa-associated lymphoid tissue is an indolent lymphoma originating from marginal zone B-cells and associated with chronic inflammation. EMZL demonstrates distinct genomic alterations according to the primary extranodal site of disease but commonly affects signaling pathways including NF-ĸB, B-cell receptor, and NOTCH. Treatment with radiation therapy is commonly implemented in localized diseases, and multiple agents are available for patients with advanced-stage diseases in need of therapy. Bendamustine with rituximab is a frontline platform associated with high efficacy.

AREAS COVERED

Clinical features, diagnosis, genomics, models enabling risk stratification, treatment options, and future directions.

EXPERT OPINION

The lack of consistent genotyping profile in EMZL precludes the development of tissue and circulatory biomarkers for the diagnosis, risk stratification, and monitoring of minimal residual disease. Furthermore, the biological heterogeneity observed in extranodal sites associated with overall limited genomic data prevents the testing of druggable pathways aiming for a personalized treatment approach. Future clinical trials should focus on EMZL considering the unique clinical characteristics in the eligibility criteria and response assessment to better inform efficacy of novel agents and delineate sequences of therapies.

Correlation between 18 F-FDG PET/CT semiquantitative parameters and Ki-67 expression in pulmonary mucosa-associated lymphoid tissue lymphoma

INTRODUCTION

This study aims to investigate the correlation between ¹⁸ F-Fluoro-d-glucose positron emission tomography/computed tomography (¹⁸ F-FDG PET/CT) semiquantitative parameters and Ki-67 expression in pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma.

METHODS

Twenty-eight patients with histologically confirmed pulmonary MALT lymphoma in 29 lesions who underwent ¹⁸ F-FDG PET/CT were retrospectively analysed. PET/CT images were analysed visually and semiquantitatively by measuring maximum standardized uptake value (SUV_max ), mean standardized uptake value (SUV_mean ), metabolic tumour volume (MTV) and total lesion glycolysis (TLG). The correlation between morphological pattern, tumour size, Ki-67 expression and PET/CT semiquantitative parameters were also analysed.

RESULTS

There were 16 male patients (57.1%) and 12 female patients (42.9%), and the mean age was 57.6 ± 9.7 years (range 43-73 years). Twenty-nine pulmonary lesions were identified in 28 patients: 12 (41.4%) presenting as consolidation, 9 (31.0%) as nodules, 5 (17.2%) as masses and 3 (10.3%) as ground glass opacities (GGOs). All of the 29 lesions were ¹⁸ F-FDG avid. SUV_max of the lesions was 4.4 ± 3.0 (range 1.1-15.3), SUV_mean was 2.8 ± 1.9 (range 0.8-10.3), MTV was 15.9 ± 17.6 (range 0.9-82.1) and TLG was 48.7 ± 56.6 (range 0.9-205.6). The PET/CT semiquantitative parameters were not correlated with morphological pattern of pulmonary MALT lymphoma, which were correlated significantly with tumour size and Ki-67 expression.

CONCLUSION

Pulmonary MALT lymphomas are ¹⁸ F-FDG avid, and ¹⁸ F-FDG PET/CT semiquantitative parameters (SUV_max , SUV_mean , MTV and TLG) are significantly correlated with tumour size and Ki-67 expression. ¹⁸ F-FDG PET/CT plays a potential role in identifying lung MALT lymphomas with higher proliferation and more aggressive behaviour in clinical practice.

Lugano classification: response evaluation criteria for positron emission tomography/computed tomography in lymphoma follow-up

Background

The purpose of this study is to assess the role of 18 fluorodeoxyglucose positron emission tomography/computed tomography (18FDG PET-CT) in the follow-up of patients with lymphoma after finishing therapy.

Results

This study included 42 lymphomas (25 non-Hodgkin’s lymphoma and 17 Hodgkin’s lymphoma); patients ranging in age from 18 to 70 years were examined by 18FDG PET-CT after therapy and analyzed retrospectively. Confirmatory biopsy was mandatory in cases of suspected disease recurrence and follow-up in cases of complete metabolic response. Positron emission tomography/computed tomography in assessment of lymphoma treatment response reveals significant statistical significance (P < 0.05). It shows 100% sensitivity, 92.8% specificity, and 95.2% accuracy in the prediction of response.

Conclusion

Positron emission tomography/computed tomography plays an important role in detection of response to treatment of lymphoma after finishing therapy.

Prognostic significance of interim PET/CT response for the treatment of advanced-stage marginal zone lymphoma in the post-rituximab era

There are still controversies about the use of interim positron emission tomography/computed tomography (PET/CT) in indolent non-Hodgkin lymphoma due to the variable fluorodeoxyglucose (FDG) avidity. Therefore, this study aimed to evaluate the roles of interim PET/CT in marginal zone lymphoma (MZL), a representative indolent lymphoma. We analyzed the data of 146 MZL patients. All were treated with rituximab-containing immunochemotherapy. Interim PET/CT scan was performed after 2–3 cycles of therapy, and the response was assessed using the Deauville 5-point scales (5-PS) and a semi-quantitative assessment using the SUVmax reduction rate (ΔSUVmax). Progression-free survival (PFS) was well stratified according to a visual assessment of interim PET/CT using 5-PS (p < 0.001). Particularly, there was a significant difference in PFS between patients with interim score 1–2 and those with score 3. However, ΔSUVmax did not predict the survival outcome using 59.8% of the optimal cutoff value. In the multivariate analysis, failure to achievement of grade 1–2 in interim PET/CT was significantly associated with inferior PFS (HR, 2.154; 95% CI 1.071–4.332; p = 0.031). The interim PET/CT response based on the 5-PS is useful for predicting PFS of patients with MZL in the post-rituximab era.

Comparison of radiologic characteristics and pathological presentations of primary pulmonary lymphoma in 22 patients

OBJECTIVE

This study was performed to compare the radiologic characteristics and pathological presentations of primary pulmonary lymphoma (PPL), explore the possible mechanism underlying its development, summarize its radiologic characteristics, and improve the accuracy of its diagnosis.

METHODS

The medical records of 22 patients pathologically diagnosed with PPL were retrospectively analyzed.

RESULTS

Chest computed tomography (CT) demonstrated single or multiple nodules and masses in the lungs, patchy opacities or consolidation along the bronchovascular bundle, and no significantly enlarged mediastinal or hilar lymph nodes. All 22 cases of PPL were classified as non-Hodgkin's lymphoma (NHL) by transbronchial biopsy, CT-guided needle biopsy, and postoperative pathology. Most (16 cases) were marginal-zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT). Twelve patients had air bronchograms within the lesion, and 13 showed ill-defined lesions with ground-glass brush-like changes.

CONCLUSION

PPL is a rare lung tumor, and most are classified as MALT lymphoma, a subtype of NHL. Chest CT can help to diagnose this disease. Positron emission tomography (PET)/CT is of great clinical value for evaluation of the lesion and patient's general condition. The possibility of PPL should be considered in patients with characteristic CT and PET/CT findings and mild clinical symptoms, and early treatment should be administered.

PET/CT in Disease Detection and Follow-up of Subcutaneous Involvement in Marginal Zone Lymphoma

BACKGROUND

The value of positron emission tomography/computed tomography (PET/CT) in the staging and assessment of treatment response in marginal zone lymphoma (MZL) lymphomas remains controversial. We investigated radiologic characteristics of subcutaneous MZL as imaged on PET/CT scans.

PATIENTS AND METHODS

From the records of a single medical center, for the years 2008 and 2017, we identified subcutaneous lesions in PET/CT scans of patients with histopathologically confirmed MZL in sites other than subcutaneous tissue.

RESULTS

Of 571 scans of 178 patients, subcutaneous lesions were found in 20 (11%). Lesions were located in soft tissue structures, mainly along the lateral aspects of the buttocks, thighs and lower and upper back areas, the flank, and the shoulders. Median lengths of the long and short axes of the lesions were 2.0 (range, 1.1-6.0) cm and 0.8 (range, 0.3-2.0) cm, respectively. Median standardized maximum uptake value was 2.3 (range, 0.9-7.6). In 12 patients (60%), MZL was diagnosed at an early stage; 15 (75%) had lymph node involvement and 10 (50%) extranodal involvement. One had spleen and 2 had cutaneous involvement; none had gastric findings.

CONCLUSION

The findings of this study support the usefulness of PET/CT in the detection of subcutaneous MZL as well as in staging and treatment decisions.

18F-FDG PET/CT or PET Role in MALT Lymphoma: An Open Issue not Yet Solved-A Critical Review

Mucosa-associated lymphoid tissue (MALT) lymphoma involves the mucosa-associated lymphoid tissue potentially arising from any mucosal site, with the stomach as the most common site of involvement. MALT lymphoma is not usually an aggressive disease with a good prognosis except for selected cases. Fluorine-18 (¹⁸F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) is a noninvasive imaging tool used for staging, restaging, and evaluation of the treatment response in non-Hodgkin and Hodgkin lymphoma. However, its effective role in MALT lymphoma is not yet clear. The open question is whether these lymphomas are ¹⁸F-FDG avid or not, with conflicting results reported in the literature. Consequently, the possible clinical role of ¹⁸F-FDG PET/CT for staging and restaging purposes is under debate. The aim of the present review was to analyze the reported data about the role of ¹⁸F-FDG PET or PET/CT in patients with MALT lymphoma. We performed a comprehensive computer literature search of the Scopus, Cochrane, PubMed/MEDLINE, and Embase databases, including articles reported up to August 2019. We included 32 studies that had analyzed ¹⁸F-FDG PET or PET/CT for patients with MALT lymphoma. We analyzed the metabolic behavior of MALT lymphoma using ¹⁸F-FDG PET and the effect of the PET findings in the staging, treatment response evaluation, and prognosis.

MRI and PET/MRI in hematologic malignancies

The role of MRI differs considerably between the three main groups of hematological malignancies: lymphoma, leukemia, and myeloma. In myeloma, whole‐body MRI (WB‐MRI) is recognized as a highly sensitive test for the assessment of myeloma, and is also endorsed by clinical guidelines, especially for detection and staging. In lymphoma, WB‐MRI is presently not recommended, and merely serves as an alternative technique to the current standard imaging test, [¹⁸F]FDG‐PET/CT, especially in pediatric patients. Even for lymphomas with variable FDG avidity, such as extranodal mucosa‐associated lymphoid tissue lymphoma (MALT), contrast‐enhanced computed tomography (CT), but not WB‐MRI, is presently recommended, despite the high sensitivity of diffusion‐weighted MRI and its ability to capture treatment response that has been reported in the literature. In leukemia, neither MRI nor any other cross‐sectional imaging test (including positron emission tomography [PET]) is currently recommended outside of clinical trials. This review article discusses current clinical applications as well as the main research topics for MRI, as well as PET/MRI, in the field of hematological malignancies, with a focus on functional MRI techniques such as diffusion‐weighted imaging and dynamic contrast‐enhanced MRI, on the one hand, and novel, non‐FDG PET imaging probes such as the CXCR4 radiotracer [⁶⁸Ga]Ga‐Pentixafor and the amino acid radiotracer [¹¹C]methionine, on the other hand.

Level of Evidence: 5

Technical Efficacy Stage: 3

J. Magn. Reson. Imaging 2020;51:1325–1335.

Clinical features and outcomes of pulmonary lymphoma: A single center experience of 180 cases

BACKGROUND

Pulmonary lymphoma arises primarily from the lung, which is extremely rare, or be secondarily involved by lymphoma. The clinical features, management, and prognostic factors have not been clearly identified.

METHODS

Sixty-three patients with primary pulmonary lymphoma (PPL) and 117 patients with secondary pulmonary lymphoma (SPL) treated in our institution between June 2003 and December 2017 were retrospectively reviewed.

RESULTS

MALT (67%) was the most common pathological subtype of PPL, while DLBCL (48%) was the most common subtype of SPL. Compared to the patients with PPL, the presence of B symptoms, advanced disease stage, intermediate-high or high risks of IPI and NCCN-IPI, elevated inflammatory parameters, and elevated cytokine levels were all observed in patients with SPL. Consolidation was the most frequent radiological finding in PPL cases, while nodules were the most frequent finding in SPL. With a median follow-up of 35 months (range 2-176), the estimated 3-year OS rates were 95%, 100%, 70% and 50% in indolent PPL, indolent SPL, aggressive PPL, and aggressive SPL, respectively. In indolent pulmonary lymphoma, none of the prognostic factors we studied significantly influenced survival of the patients. In aggressive pulmonary lymphoma, univariate analysis showed that NCCN-IPI was related to OS in PPL. Multivariate analysis showed that β2-MG was an independent prognostic factor for OS in SPL.

CONCLUSIONS

Primary and secondary pulmonary lymphoma differ in their clinical features and outcome. Furthermore, β2-MG is the independent prognostic factor for OS in patients with aggressive SPL.

Uptake of [18F]fluorodeoxyglucose in initial positron-emission tomography predicts survival in MALT lymphoma

The role of [¹⁸F]fluorodeoxyglucose (FDG) positron-emission tomography (PET) in mucosa-associated lymphoid tissue (MALT) of marginal zone lymphoma remains poorly defined. We correlated initial PET with pathology, clinical factors, and outcome. From January 2001 to July 2012, 173 MALT lymphoma patients with a biopsied lesion identified on PET within 90 days of tissue biopsy were analyzed. PET positivity and intensity of FDG uptake were correlated with clinical factors and patient outcome. Among 173 accrued cases, biopsied site was PET avid in 123 patients (71%); median standardized uptake value (SUV) was 6.0 (range: 0.7-28.0), and SUV >10.0 in 20 patients (16%). PET avidity varied by organ sites. PET positivity correlated with higher International Prognostic Index, but not with 5-year overall survival (OS; 96% vs 88%, PET negative vs positive, P = .229) or 5-year progression-free survival (67% vs 56%, P = .493). SUV was an independent prognostic factor of OS, and an increased SUV was associated with a decreasing 5-year OS. Patients who presented with SUV ≥10 had a higher rate of subsequent large cell transformation (20% vs 5%, P = .035) and inferior OS (78% vs 92%, P = .008). The exact role of FDG PET in the management of MALT lymphoma, beyond initial staging, remains to be defined.

A young man with an unchanged consolidation in chest CT

Primary pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma is extremely rare. MALT lymphoma patients usually show no clinical symptoms or physical signs. Chest radiograph or computed tomography (CT) may confuse MALT lymphoma with other pulmonary diseases, which would lead to misdiagnosis or a delayed diagnosis. In the present study, a 33-year-old male patient had cough and fever. Chest CT showed consolidation on both sides. Those clinical symptoms disappeared after he had been misdiagnosed and treated for community-acquired pneumonia for three weeks. However, further chest CT still showed the consolidation without any change. Then an ultrasonic guided transthoracic needle biopsy was performed. Morphological changes indicated the diagnosis of extranodal marginal Zone B cell lymphoma of MALT. The patient was then treated with chemotherapy and rituximab. After this line of treatment, the consolidation decreased.

Uptake Patterns of Untreated Primary Gastrointestinal Extranodal Lymphomas on Initial Staging 18F-FDG PET/CT and Metabolic Tumor Parameters

Objective:

Non-Hodgkin’s lymphomas arising from tissues other than primary lymphatic sites are classified as primary extranodal lymphomas (PEL). PELs of the gastrointestinal system (PGISL) originate from the lymphatic tissues within the gastrointestinal tract. The prognostic value of ¹⁸F-FDG PET/CT in lymphomas is high in terms of both overall survival (OS) and disease-free survival (DFS). Our aim was to investigate the uptake patterns and properties of low-grade and high-grade PGISL on primary staging ¹⁸F-FDG PET/CT, as well as the prognostic significance of metabolic tumor parameters in high grade PGISL.

Methods:

Thirty-nine patients with PGISL were enrolled in this retrospective cohort study between 2004-2015. Primary staging ¹⁸F-FDG PET/CT have been performed and quantitative parameters of SUV_max, SUV_mean, metabolic tumor volume (MTV), total lesion glycolysis (TLG) have been calculated for all patients prior to treatment. Low-grade and high-grade PGISL were compared in terms of metabolic tumor parameters. Cox regression models were performed to determine factors that correlate with DFS in high-grade PGISL.

Results:

There were statistically significant differences between high-grade and low-grade PGISL in terms of SUV_max, SUV_mean, MTV, TLG, recurrence, mortality, DFS and OS. None of the potential risk factors (sex, age, site, SUV_max, SUV_mean, MTV, TLG) for recurrence and metastasis in high grade PGISL was identified as a risk factor on univariate and multivariate Cox regression analysis.

Conclusion:

Metabolic tumor parameters are not predictive markers in high-grade PGISL, especially in diffuse large B cell variant and primary gastric lymphoma. The first implications suggest they will not play a role in patient management.

Pulmonary mucosa-associated lymphoid tissue lymphoma: 18F-FDG PET/CT and CT findings in 28 patients

OBJECTIVE

The aim of the study was to evaluate the CT and fluorine-18-fluorodeoxyglucose positron emission tomography/CT (¹⁸F-FDG PET/CT) imaging findings of lung mucosa associated lymphoid tissue (MALT) lymphoma.

METHODS

28 patients with histologically confirmed pulmonary MALT lymphoma who underwent a chest CT and ¹⁸F-FDG PET/CT for staging were retrospectively analysed. The CT images were evaluated to determine morphological pattern of appearance, laterality, localization, number, size, presence of thoracic lymphadenopaties and secondary/combined findings. PET images were analysed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio and lesion-to-blood pool SUVmax ratio. The relationship between qualitative and semi-quantitative features at ¹⁸F-FDG PET/CT and CT findings were also analysed.

RESULTS

A total of 57 pulmonary lesions were identified by CT: 37 areas of consolidation, 4 masses, 12 nodules and 4 ground-glass opacities. Solitary and multiple lesions were detected in 10 and 18 patients, respectively; among patients with multiple lesions, 16 were bilateral and 2 unilateral. ¹⁸F-FDG PET/CT revealed increased ¹⁸F-FDG uptake in 47/57 lesions, in 26/28 patients. 18F-FDG avidity was significantly associated only with tumour size.

CONCLUSIONS

Pulmonary MALT lymphoma is ¹⁸F-FDG avid in most cases and ¹⁸F-FDG avidity is correlated with tumour size. Consolidation is the most frequent morphological pattern of disease presentation. Advances in knowledge: This study demonstrated that lung MALT lymphoma are ¹⁸F-FDG avid in most cases depending on tumour size. Single or multiple areas of consolidation are the most common pattern of presentation of lung MALT lymphoma at CT.

Complete metabolic response (CMR) in positron emission tomography-computed tomography (PET-CT) scans may have prognostic significance in patients with marginal zone lymphomas (MZL)

Although clinical use of positron emission tomography-computed tomography (PET-CT) scans is well established in aggressive lymphomas, its prognostic value in marginal zone lymphoma (MZL) remains yet unclear. Hence, we investigated potential role of PET-CT in predicting MZL patients' outcomes following systemic chemotherapy. A total of 32 patients with MZL who received first-line chemotherapy were included in the analysis. They all underwent pretreatment, interim, and posttreatment PET-CT scans. The primary objective was to evaluate the role of complete metabolic response (CMR) in posttreatment PET-CT scans in predicting progression-free survival (PFS). Compared with non-CMR group, 5-year PFS rate was significantly higher in patients who achieved CMR in posttreatment PET-CT (54.2% vs 0.0%, P = .003) and also in patients gaining CMR in interim PET-CT scans (62.5% vs 15.6%, P = .026). Interestingly, early CMR group, who achieved and maintained CMR in both interim and posttreatment PET-CT scans, showed significantly higher 5-year PFS than those with delayed or never CMR group (62.5% vs 37.5% vs 0%, P = .008). Therefore, interim and/or posttreatment CMR can be prognostic at least in these subsets of patients with MZL treated with chemotherapy.

[18 F]-FDG PET/CT in the staging and management of indolent lymphoma: A prospective multicenter PET registry study

BACKGROUND

To measure the clinical impact of pretreatment fludeoxyglucose positron emission tomography/computed tomography (PET/CT) on the staging and management of apparent limited stage indolent lymphoma being considered for curative radiation therapy.

METHODS

We conducted a prospective multicenter registry study that included 197 patients accrued between May 1, 2012, and December 31, 2015. Pre-PET/CT stage, determined by clinical and CT data, was documented. If pre-PET/CT stage was indeterminate, a stage was assigned to the patient by the referring oncologist according to best clinical judgment and treatment intent. After PET/CT, revised stage and planned management were recorded and compared with data on actual treatment received available through provincial databases (n = 155).

RESULTS

PET/CT resulted in the upstaging of 47 (23.9%) patients with presumed limited stage disease (stage I-II) to advanced stage disease (stage III-IV) (P < .0001). Ten (5.1%) patients were downstaged by PET/CT, 4 of whom migrated from advanced to limited stage disease. Twenty-eight (14.2%) patients with a specific pre-PET/CT stage had equivocal PET/CT findings that required further evaluation to confirm disease extent. After PET/CT, 95 (61.3%) patients were planned to receive active treatment. Of the 59 patients planned for radiotherapy alone post-PET/CT, 34 (57.6%) received this treatment (P = .002), and nearly 80% of them (n = 27) had confirmed limited stage disease.

CONCLUSION

PET/CT has a significant impact on staging and management in patients with apparent limited stage indolent lymphoma who are being considered for curative radiotherapy. PET/CT should be routinely incorporated into the workup of these patients. Cancer 2017;123:2860-66. © 2017 American Cancer Society.

Mucosa-associated lymphoid tissue lymphoma with unusual 18F-FDG hypermetabolism arising at the colorectal anastomosis

Mucosa-associated lymphoid tissue (MALT) lymphoma usually originates from the stomach and presents with low ¹⁸F-fluorodeoxyglucose (FDG) avidity with average maximum standard uptake value of 3.6. Colorectal MALT lymphoma is a rare entity that contributes to 1.6% of all MALT lymphomas and < 0.2% of large intestinal malignancies. The case reported herein firstly revealed stage IIE MALT lymphoma with unexpected higher ¹⁸F-FDG avidity of 18.9 arising at the colorectal anastomosis in a patient with a surgical history for sigmoid adenocarcinoma, which was strongly suspected as local recurrence before histopathological and immunohistochemical examinations. After accurate diagnosis, the patient received four cycles of standard R-CVP regimen (rituximab, cyclophosphamide, vincristine and prednisone), combined target therapy and chemotherapy, instead of radiotherapy recommended by National Comprehensive Cancer Network guidelines. He tolerated the treatment well and reached complete remission.

18F-fluorodeoxyglucose positron emission tomography/computed tomography comparison of gastric lymphoma and gastric carcinoma

AIM

To compare ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) features in gastric lymphoma and gastric carcinoma.

METHODS

Patients with newly diagnosed gastric lymphoma or gastric carcinoma who underwent ¹⁸F-FDG PET/CT prior to treatment were included in this study. We reviewed and analyzed the PET/CT features of gastric wall lesions, including FDG avidity, pattern (focal/diffuse), and intensity [maximal standard uptake value: (SUVmax)]. The correlation of SUVmax with gastric clinicopathological variables was investigated by χ² test, and receiver-operating characteristic (ROC) curve analysis was performed to determine the differential diagnostic value of SUVmax-associated parameters in gastric lymphoma and gastric carcinoma.

RESULTS

Fifty-two patients with gastric lymphoma and 73 with gastric carcinoma were included in this study. Abnormal gastric FDG accumulation was found in 49 patients (94.23%) with gastric lymphoma and 65 patients (89.04%) with gastric carcinoma. Gastric lymphoma patients predominantly presented with type I and type II lesions, whereas gastric carcinoma patients mainly had type III lesions. The SUVmax (13.39 ± 9.24 vs 8.35 ± 5.80, P < 0.001) and SUVmax/THKmax (maximal thickness) (7.96 ± 4.02 vs 4.88 ± 3.32, P < 0.001) were both higher in patients with gastric lymphoma compared with gastric carcinoma. ROC curve analysis suggested a better performance of SUVmax/THKmax in the evaluation of gastric lesions between gastric lymphoma and gastric carcinoma in comparison with that of SUVmax alone.

CONCLUSION

PET/CT features differ between gastric lymphoma and carcinoma, which can improve PET/CT evaluation of gastric wall lesions and help differentiate gastric lymphoma from gastric carcinoma.

18F-FDG PET/CT in gastric MALT lymphoma: a bicentric experience

PURPOSE

The role of 18F-FDG-PET/CT in evaluating gastric MALT lymphoma is still controversial. In the literature the detection rate of 18F-FDG-PET/CT in patients with gastric MALT lymphoma is variable, and the reason for this heterogeneity is not still clear. Our aim was to investigate the particular metabolic behavior of these lymphoma.

MATERIALS AND METHODS

Sixty-nine patients (26 female, 43 male) with histologically confirmed gastric MALT lymphoma who underwent a 18F-FDG-PET/CT for initial staging from two centers were included. The PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio and compared with Ann Arbor stage, epidemiological (age, sex), histological (presence of gastritis, ulcer, H. pylori infection, plasmacytic differentiation, Ki-67 index), and morphological (tumor size, superficial lesions or mass-forming) characteristics.

RESULTS

Thirty-six patients (52 %) had positive PET/CT (average SUVmax was 9±6.7; lesion-to-liver SUVmax ratio 3.7±2.6, lesion-to-blood pool SUVmax ratio 4.8±3.3) at the corresponding gastric lesion; the remaining 33 were not 18F-FDG-avid. In the univariate analysis, 18F-FDG avidity was significantly associated with morphological features (mass forming p<0.001 and high maximum diameter p<0.001), Ann Arbor stage (p=0.010), and Ki67 index (p<0.001) and not correlated with age, sex, presence of gastritis, ulcer, Helicobacter pylori infection, and plasmacytic differentiation. In the multivariate analysis, the correlations with gross morphological appearance, Ann Arbor stage, and Ki-67 score were confirmed. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio correlated significantly only with Ki67 index (p=0.047; p=0.012; p=0.042).

CONCLUSIONS

18F-FDG avidity was noted in 52 % of gastric MALT lymphoma and this avidity is correlated with gross morphological characteristics, tumor stage, and Ki-67 index. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio are correlated only with Ki-67 index, and only lesion-to-liver SUVmax ratio was independently associated with Ki-67 score.

Prognosis estimation under the light of metabolic tumor parameters on initial FDG-PET/CT in patients with primary extranodal lymphoma

Background

Non-Hodgkin’s lymphomas arising from the tissues other than primary lymphatic organs are named primary extranodal lymphoma. Most of the studies evaluated metabolic tumor parameters in different organs and histopathologic variants of this disease generally for treatment response. We aimed to evaluate the prognostic value of metabolic tumor parameters derived from initial FDG-PET/CT in patients with a medley of primary extranodal lymphoma in this study.

Patients and methods

There were 67 patients with primary extranodal lymphoma for whom FDG-PET/CT was requested for primary staging. Quantitative PET/CT parameters: maximum standardized uptake value (SUVmax), average standardized uptake value (SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were used to estimate disease-free survival and overall survival.

Results

SUVmean, MTV and TLG were found statistically significant after multivariate analysis. SUVmean remained significant after ROC curve analysis. Sensitivity and specificity were calculated as 88% and 64%, respectively, when the cut-off value of SUVmean was chosen as 5.15. After the investigation of primary presentation sites and histo-pathological variants according to recurrence, there is no difference amongst the variants. Primary site of extranodal lymphomas however, is statistically important (p = 0.014). Testis and central nervous system lymphomas have higher recurrence rate (62.5%, 73%, respectively).

Conclusions

High SUVmean, MTV and TLG values obtained from primary staging FDG-PET/CT are potential risk factors for both disease-free survival and overall survival in primary extranodal lymphoma. SUVmean is the most significant one amongst them for estimating recurrence/metastasis.

CT, MRI, and 18F-FDG PET/CT Findings in Untreated Pulmonary and Hepatic B-Cell Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT) Over a Five-Year Period: A Case Report

Imaging findings of hepatic lymphoma of mucosa-associated lymphoid tissue (MALT) have been rarely reported before. We present the computed tomography (CT), magnetic resonance imaging (MRI), and fluorine-18-fluorodeoxyglucose (F-FDG) positron emission tomography (PET)/CT findings in a patient with untreated pulmonary and hepatic MALT lymphoma over a 5-year period.On the 1st abdominal MRI scan, the hepatic MALT lymphoma showed multiple hepatic subcapsular masses. On FDG PET/CT, these hepatic tumors showed hypodenisty with FDG uptake similar to the liver on early PET images, and higher than liver on delayed PET images. The patient declined to undergo treatment. Fiver year later, the follow-up MRI and FDG PET/CT showed enlargement and confluence of the hepatic tumors with higher FDG uptake than before. The enlarged hepatic tumors had minimal mass effect. In the hepatic lesions, the blood vessels and bile ducts had no distortion or displacement.The hepatic MALT lymphoma should be taken into consideration when the hepatic tumors have minimal mass effect with the intrahepatic blood vessels and bile ducts normally passing through the tumors. Delayed-time-point FDG PET/CT imaging may be helpful for improving detectability of the hepatic MALT lymphoma.

Pulmonary mucosa-associated lymphoid tissue lymphoma revisited

This general review sought to clarify the pathophysiological, diagnostic, prognostic, and therapeutic features of pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma.MALT lymphoma is the most common pulmonary B-cell lymphoma, which usually occurs in the context of acquired MALT. The disease is slow-growing with an asymptomatic chronic alveolar opacity visible on radiography. Diagnosis requires tissue samples that should be retrieved using minimally invasive techniques, such as bronchoscopy or computed tomography-guided biopsies. The pathophysiology includes cytogenetic abnormalities and autoimmune diseases, whereas an association with a chronic pulmonary infection is still suspected but not yet demonstrated. Disease prognosis is typically excellent and the current available treatments are discussed in this review, including the decision not to treat, surgery, and single- or double-agent chemotherapy.

18F-Fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography in mucosa-associated lymphoid tissue lymphoma: variation in 18F-FDG avidity according to site involvement

The purpose of this study was to determine the 18F-FDG avidity of MALT lymphoma and the additional utility of 18F-FDG PET/CT in MALT lymphoma staging. Pretreatment 18F-FDG PET/CT scans of 222 patients with 227 MALT lymphoma lesions were retrospectively analyzed. 18F-FDG avidity of lesions was noted in 28%. The proportion was lower for gastric MALT lymphomas than for non-gastric lesions (9% vs. 60%, p<0.0001) and higher for mass-forming lesions than for superficial lesions (82% vs. 2%, p<0.0001). 18F-FDG PET/CT showed the presence of additional lesions in 23 patients: four of six true-positive lesions had 18F-FDG avid primary lesions, and 15 of 17 false-positive lesions had 18F-FDG-non avid lesions. 18F-FDG avidity differed according to the location and gross morphologic characteristics of the MALT lymphoma. Most gastric MALT lymphomas were superficial and had low 18F-FDG avidity. For staging, 18F-FDG PET/CT can be helpful mainly for 18F-FDG avid primary MALT lymphomas.

Imaging for Staging and Response Assessment in Lymphoma

Lymphoma comprises a heterogeneous group of diseases; remarkable advances have been made in diagnosis and treatment. Diagnostic imaging provides important information for staging and response assessment in patients with lymphoma. Over the years, staging systems have been refined, and dedicated criteria have been developed for evaluating response to therapy with both computed tomography (CT) and fluorine-18 fluorodeoxyglucose positron emission tomography (PET)/CT. The most recent system proposed for staging and response assessment, known as the Lugano classification, applies to both Hodgkin and non-Hodgkin lymphoma. The use of standardized criteria for staging and response assessment is important for making accurate treatment decisions and for determining the direction of further research. This review provides an overview of the updated CT and PET response criteria to familiarize the radiologist with the most important and clinically relevant aspects of lymphoma imaging. It also provides a short clinical update on lymphoma and the associated spectrum of imaging findings.

The use of FDG-PET in diffuse large B cell lymphoma (DLBCL): predicting outcome following first line therapy

Positron emission tomography (PET) using 18fluoro-2-deoxyglucose (FDG) has become a standard clinical tool for staging and response assessment in aggressive lymphomas. The use of PET scans in clinical trials is still under exploration, however. In this review, we examine current data regarding PET in DLBCL, and its potential applicability to development of a surrogate endpoint to expedite clinical trial conduct. Interim PET scanning in DLBCL shows mixed results, with qualitative assessment variably associated with outcome. Addition of quantitative assessment might improve predictive power of interim scans. Data from multiple retrospective studies support that PET-defined response at end of treatment correlates with outcome in DLBCL. Optimal technical criteria for standardization of acquisition and criteria for interpretation of scans require further study. Prospective studies to define the correlation of PET-defined response and time-dependent outcomes such as progression free survival (PFS) and overall survival (OS), critical for development of PET as a surrogate endpoint for clinical trials, are ongoing. In conclusion, evolving data regarding utility of PET in predictcing outcome of patients with DLBCL show promise to support the use of PET as a surrogate endpoint in clinical trials of DLBCL in the future.

Clinical value of 18F-FDG PET/CT in diagnosis and follow-up of primary gastric lymphoma

AIM: To assess the clinical value of ¹⁸F-fluorodeoxygiucose positron emission computed tomography (¹⁸F-FDG PET/CT) in the diagnosis and follow-up of primary gastric lymphoma (PGL).

METHODS: Thirty-five patients with endoscopically or pathologically confirmed PGL were enrolled into this study. Among them, 12 patients underwent pre-treatment ¹⁸F-FDG PET/CT scans, and the other 23 patients (32 episodes) underwent a total of 32 post-treatment ¹⁸F-FDG PET/CT scans, with 8 scanned 2-3 times. The lesions on the images of ¹⁸F-FDG PET/CT were observed and analyzed, and the SUVmax was measured.

RESULTS: Among the 12 patients who underwent pre-treatment ¹⁸F-FDG PET/CT scans, 5 had infiltration type PGLs and showed gastric wall thickening [SUVmax = 22.5 ± 7.6 (7.2-30.9), average thickness = 3.4 cm ± 1.3 cm (1.2-4.8 cm)], 6 had nodule type [SUVmax = 24.2 ± 13.0 (5.8-39.4), average diameter = 2.8 cm ± 1.5 cm (1.0-4.6 cm), and 1 had mass type (SUVmax = 21.0, size = 19.5 cm × 1.4 cm). Among the 23 patients who underwent after-treatment ¹⁸F-FDG PET/CT scans, using endoscopic pathology or clinical follow-up beyond six months as standard, 11 had negative images, and the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of ¹⁸F-FDG PET/CT were 83.3% (10/12), 1.7% (11/12), 87.5% (21/24), 84.6% (11/13) and 84.6% (11/13), respectively.

CONCLUSION: ¹⁸F-FDG PET/CT plays an important role in the pre-treatment diagnosis of PGL as well as post-treatment surveillance of PGL from a clinical perspective.

Role of 18F-FDG-PET/CT in the management of marginal zone B cell lymphoma

The use of PET in patients with marginal zone B cell lymphoma (MZL) is controversial because of variability of fluorodeoxyglucose (FDG) avidity. We analyzed 40 PET/CT in 25 consecutive patients to compare its performance with CT at staging and as a first-line response assessment. Sensitivity of PET/CT and CT was 96 and 76%. Mean standard uptake value was 6.1, 6.9 and 3.4 (p = 0.3) in nodal, extranodal and splenic subtypes, respectively. Of 17 patients (extranodal: n = 9; nodal: n = 6; splenic subtype: n = 2) with both imaging tests available at diagnosis, 8 (47%) had more involved areas with PET/CT than with CT, 75% of which were extranodal lesions. PET/CT resulted in upstaging of five patients although treatment of only two of them was changed. Responses of 15 patients with post-treatment PET/CT were the following: 9 negative and 6 positive of which 3 were isolated residual lesions. Progression was documented in two of these three patients. Response was also assessed by CT in 11 patients. Discrepancies were found in three: Two were in complete remission by CT while PET/CT detected localized residual disease; another patient was in partial remission by CT, whereas PET/CT showed only one positive lesion. Two of these three patients relapsed. Patients with negative post-treatment PET/CT did not relapse. With a median follow-up of 50 months (10-152 months), 3-year overall survival was 100 and 80% for patients with negative and positive post-treatment PET/CT (p = 0.2). Three-year disease-free survival was 86%; the negative predictive value (NPV) was 100%, and the positive predictive value (PPV) was 83.3%. Although a larger number of patients will be required to further confirm these data, we can conclude that PET/CT is a useful imaging tool for both staging and response assessment in patients with nodal and extranodal MZL as a result of its high sensitivity, NPV and PPV.

Adnexal mass secondary to extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) with associated amyloid deposition

Systemic amyloid light chain amyloidosis (AL amyloidosis) is usually seen in association with a plasma cell disorder. Amyloid deposition associated with extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is a rare phenomenon that is not typically associated with systemic AL amyloidosis. We describe the unusual case of a patient with an adnexal mass secondary to MALT lymphoma with associated amyloid deposition.

18F-FDG PET scanning in pulmonary amyloidosis

(18)F-FDG PET plays an important role in the evaluation of patients with lung malignancies but can lead to false-positive and false-negative results. Very little is known about (18)F-FDG PET scanning in amyloidosis.

METHODS

A computer-assisted search of medical records was conducted to identify subjects with pulmonary amyloidosis (confirmed by biopsy) who were seen at the Mayo Clinic during a 15-y period between January 1, 1997, and December 31, 2011, and had a PET scan available for current review.

RESULTS

Eighteen patients were diagnosed to have amyloidosis by lung biopsy (15 surgical, 2 transthoracic needle, and 1 bronchoscopic). The mean age of the patients was 64.8 y (range, 32-80 y). Seventeen patients had primary amyloidosis, including 5 with Sjögren syndrome, 1 with rheumatoid arthritis, and 1 with multiple myeloma. The most common abnormal findings on the chest CT scan were pulmonary nodules (n = 14), followed by cysts (n = 6) and reticular opacities (n = 4). Eight patients had positive (18)F-FDG PET results (intrathoracic (18)F-FDG uptake), including 4 patients with coexisting mucosa-associated lymphoid tissue lymphoma (maximal standardized uptake value [SUVmax] range, 3.1-6.7) and 1 patient with a pleural plasmacytoma (SUVmax, 7.2); the remaining 3 patients had amyloid only (SUVmax range, 2.1-3.2). Ten patients with negative PET results included 3 additional patients with mucosa-associated lymphoid tissue lymphoma.

CONCLUSION

Positive (18)F-FDG PET results, especially with an SUVmax of more than 3, in patients with pulmonary amyloidosis should raise suspicion about associated lymphoma or plasmacytoma, but negative PET results do not exclude the presence of such neoplasms.

Current role of FDG PET/CT in lymphoma

The management approach in Hodgkin's (HL) and high-grade non-Hodgkin's lymphomas (NHL) has shifted towards reducing the toxicity and long-term adverse effects associated with treatment while maintaining favorable outcomes in low-risk patients. The success of an individualized treatment strategy depends largely on accurate diagnostic tests both at staging and during therapy. In this regard, positron emission tomography (PET) using fluorodeoxyglucose (FDG) with computed tomography (CT) has proved effective as a metabolic imaging tool with compelling evidence supporting its superiority over conventional modalities, particularly in staging and early evaluation of response. Eventually, this modality was integrated into the routine staging and restaging algorithm of lymphomas. This review will summarize the data on the proven and potential utility of PET/CT imaging for staging, response assessment, and restaging, describing current limitations of this imaging modality.

Sarcoidosis lymphoma syndrome - the value of PET-CT in the diagnosis

We report a 52-year-old patient who developed B-cell non-Hodgkin’s lymphoma subsequent to sarcoidosis. Sarcoidosis was diagnosed 16 years ago and remained asymptomatic for 14 years after steroid treatment. She presented with new symptoms of arthralgia, photosensitivity, butterfly erythema, autoimmune antibodies (ANA, chromatin positivity) associated with progression of the known left upper lobe lesion on the chest X-ray suggesting primary autoimmune disease (systemic lupus erythematosus). As steroid treatment was not effective, we started bolus cyclophosphamide therapy after which progression was seen on the chest X-ray. Computed tomography (CT)-guided needle biopsy confirmed malignancy of indefinable origin. Despite of the well-known fluorodeoxyglucose (FDG) avidity in active sarcoidosis, a FDG-positron emission tomography (PET) scan was performed to stage the primary tumour. Intensive FDG uptake was detected in the affected lung segment, with moderate uptake in mediastinal lymph nodes. The patient underwent left upper lobectomy. The histology showed pulmonary mucosa-associated lymphoma (bronchus-associated lymphoid tissue (BALT) lymphoma) in the lung tissue, while only sarcoidosis was present in the mediastinal lymph nodes. Bone marrow biopsy was negative.

The association between sarcoidosis and lymphoma is known as sarcoidosis lymphoma syndrome, which is a rare disease. PET-CT was helpful in the differentiation of sarcoidosis and malignancy in this patient. It is important to be aware of the risk of lymphoma in sarcoidosis and FDG-PET, used for adequate purpose, can help the diagnosis.

State-of-the-Art Research on "Lymphomas: Role of Molecular Imaging for Staging, Prognostic Evaluation, and Treatment Response"

Lymphomas are heterogeneous but potentially curable group of neoplasms. Treatment of lymphomas has rapidly evolved overtime with significant improvement in the cure rate and reductions in treatment-related toxicities. Despite excellent results, treatment programs are continued to be developed to achieve better curative and safety profiles. In these patients individualized therapy schemes can be devised based on a well-defined risk categorization. The therapy efficacy can be increased early during therapy in non-responding patients with escalated therapy protocols or with the addition of radiation therapy, particularly, in advanced-stage or unfavorable risk patients. The increasing availability of positron emission tomography using 18F-fluorodeoxyglucose, particularly fused with computed tomography (FDG-PET/CT) has lead to the integration of this modality into the routine staging and restaging for lymphoma with convincing evidence that it is a more accurate imaging modality compared with conventional imaging techniques. FDG-PET/CT is also is a promising surrogate for tumor chemosensitivity early during therapy. This review will summarize published data on the utility of FDG-PET/CT imaging in the staging, restaging, and predicting therapy response in patients with lymphoma.

Primary gastric lymphoma: utility of 18F-fluorodeoxyglucose positron emission tomography-computed tomography for detecting relapse after treatment

The purpose of this study was to evaluate the role of 18F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography-computed tomography (PET-CT) in detecting relapse in patients with primary gastric lymphoma (PGL) post-treatment. Data of 39 previously treated patients with PGL (age: 50.3 ± 13.8 years; male: 24) who underwent 71 (18)F-FDG PET-CT studies for suspected relapse (n = 53) or routine follow-up (n = 18) were retrospectively evaluated. PET-CT images were evaluated both qualitatively and quantitatively (standardized uptake value [SUVmax]). A combination of clinical/imaging follow-up, endoscopy and/or histopathology was taken as the reference standard. The per patient based sensitivity of PET-CT was 96%, specificity 91% and accuracy 93%. The lymph node was the commonest site of relapse on PET-CT. Mean lesion SUVmax was 5.9 ± 3.1 (2.3-13.6). Accuracy was similar in suspected relapse and routine follow-up groups (90.5% vs. 100%; p = 0.409). Based on the data, (18)F-FDG PET-CT appears to be highly accurate for the detection of relapse in patients with PGL post-treatment.