The 2023 revised diagnostic criteria for IgG4-related ophthalmic disease.

Immunoglobulin G4 (IgG4)-related disease is a clinical entity characterized by elevated serum IgG4 concentrations and infiltration of IgG4-immunopositive plasmacytes in various organs, including ophthalmic lesions. Diagnostic criteria for IgG4-related ophthalmic disease (IgG4-ROD) were established in 2014 and describe the most affected ocular adnexal tissues such as lacrimal glands, trigeminal nerves and extraocular muscles, but do not mention optic neuropathy, the most severe indication of ophthalmic lesions. We reviewed published case reports of optic neuropathy in IgG4-related disease (n = 44), and in many cases, decreased visual acuities recovered well following treatment such as systemic corticosteroids, rituximab, and orbital surgery. However, some patients did not recover, especially when pretreatment visual acuities were as low as light perception or less. Herein, we propose a 2023 revised diagnostic criteria for IgG4-ROD, which include a reminder not to overlook optic neuropathy. The 2014 diagnostic criteria specify mucosa-associated lymphoid tissue (MALT) lymphoma as an important differential diagnosis for the relationship between IgG4-ROD and orbital lymphoma. The 2023 revision directs physicians' attention toward lymphomas other than MALT lymphoma, considering that the 2014 criteria might have placed too much emphasis on MALT lymphoma.

Molecular Mechanisms and Treatment Strategies for Helicobacter pylori-Induced Gastric Carcinogenesis and Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma.

Helicobacter pylori has been classified as a class I carcinogen by WHO because of its primary involvement in the development of gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. This review focuses on understanding the molecular pathophysiological mechanisms that operate within intracellular transduction pathways and their relevance in the treatment strategies for the two main diseases caused by H. pylori. H. pylori virulence factors such as cytotoxin-associated gene A and vacuolating cytotoxin A genotypes, inflammatory mediators, H. pylori-induced microRNA deregulation, alterations in autophagy proteins and regulators, and changes in DNA methylation are some of the molecular mechanisms that play essential roles in H. pylori infection and gastric carcinogenesis. The discovery of novel treatment strategies that target the deregulated intracellular transduction pathways in gastric carcinogenesis and MALT lymphoma is critical. H. pylori eradication (HPE) is not limited to H. pylori-dependent low-grade MALT lymphoma and may be used in patients with high-grade diffuse large B-cell lymphoma (DLBCL) (de novo or DLBCL-MALT lymphoma). The loss of H. pylori dependency and high-grade transformation appear to be distinct events in the progression of gastric lymphoma. Interestingly, patients with H. pylori-positive gastric DLBCL without histological evidence of MALT lymphoma (pure gastric DLBCL) may respond to HPE therapy.

Simultaneous primary thyroid MALT lymphoma and papillary thyroid cancer.

The mucosa-associated lymphoid tissue (MALT) lymphoma subtype, specifically extranodal marginal zone B-cell lymphoma, is a rare variant. Within this subtype, primary thyroid MALT lymphoma is an uncommon occurrence. The literature provides limited documentation on thyroid MALT lymphomas, as their prevalence is comparatively lower than in other organ sites. The coexistence of papillary thyroid carcinoma (PTC) and thyroid MALT lymphomas is exceedingly rare. It presents a rare case of primary thyroid MALT lymphoma accompanied by PTC, thyroid lymphoma not being considered before surgery. A 64-year-old female patient, who had been experiencing symptoms related to a substantial thyroid tumor for a duration of three years, she refused to do a needle biopsy before surgery and expressed a preference for surgical resection. Consequently, the patient underwent a total thyroidectomy along with lymphadenectomy of the central compartment. A histological examination subsequently confirmed the presence of papillary thyroid carcinoma (PTC) and mucosa-associated lymphoid tissue (MALT) lymphoma. Due to the favorable response of the MALT lymphoma to local treatment and the absence of metastasis in other organs, no further treatment was administered for the MALT lymphoma following the surgery. Currently, the patient exhibits no signs of tumor recurrence based on ultrasound and laboratory evaluations. We also provide an overview of the clinical findings on PTC and MALT lymphoma patients already reported and discuss the possible treatment strategy.

Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma of the Urinary Bladder: A Case Report of a Rare Presentation.

Primary lymphoma of the urinary bladder is extremely rare. We present the case of a 67-year-old woman diagnosed with primary extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT) of the urinary bladder. The patient presented with macroscopic hematuria. Renal ultrasound revealed a solid vascularized mass, in the inferior wall of the bladder. Pelvic computed tomography (CT) and magnetic resonance imaging (MRI) confirmed the presence of a polypoid lesion on the left side of the inferior bladder wall, measuring 40x45 mm, and the MRI study with gadolinium revealed that the entire bladder wall was involved. The patient underwent transurethral resection of the bladder tumor, demonstrating a histologic extensive involvement of bladder tissue by MALT lymphoma. The patient was treated with radiotherapy (24 Gy in 12 fractions) and four cycles of rituximab. She remained without evidence of disease 12 months later.

Thymic MALT lymphoma associated with Sjögren's syndrome with postoperative cardiac tamponade and acute pleuritis: a case report.

BACKGROUND: Thymic mucosa-associated lymphoid tissue (MALT) lymphoma is rare and is known to be associated with Sjögren's syndrome (SjS). SjS is rarely accompanied by serositis. Here, we describe the first case of postoperative cardiac tamponade and acute pleuritis in a patient with thymic MALT lymphoma associated with SjS. CASE PRESENTATION: A 33-year-old woman with SjS presented with an anterior mediastinal mass on chest computed tomography, which was performed for further examination of the condition. Suspecting a thymic MALT lymphoma or thymic epithelial tumor, total thymectomy was performed. The mediastinal mass was histopathologically diagnosed as a thymic MALT lymphoma. The patient was discharged with a good postoperative course but visited the hospital 30 days after surgery for dyspnea. Cardiac tamponade was observed and drainage was performed. Four days after pericardial drainage, chest radiography revealed massive left pleural effusion, and thoracic drainage was performed. The patient was diagnosed with serositis associated with SjS and treated with methylprednisolone, which relieved cardiac tamponade and pleuritis. CONCLUSIONS: Surgical invasion of thymic MALT lymphomas associated with SjS may cause serositis. Postoperative follow-up should be conducted, considering the possibility of cardiac tamponade or acute pleuritis due to serositis as postoperative complications.

The National Landscapes of Gastric Mucosa-Associated Lymphoid Tissue Lymphoma: Stable Trends in Black Populations and Late-Stage Tumors.

BACKGROUND: Helicobacter pylori (H. Pylori) eradication has been the mainstream for preventing and treating gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Prior data showed disparities in eradication rates of H. Pylori between different populations. This can potentially impact the occurrence of gastric MALT lymphoma. There are limited data on the incidence and mortality rates and trends of gastric MALT lymphoma in the US. Therefore, the aim of the current study was to conduct a time-trend analysis of gastric MALT lymphoma incidence and mortality rates in different populations. METHODS: The incidence rates of gastric MALT lymphoma were calculated from the United States Cancer Statistics (USCS) database (which covers nearly 98% of the US population) between 2001-2020 and were age-adjusted to the standard 2000 US population using SEER*Stat software (version 8.4.3, national cancer institute "NCI"). Incidence-based mortality (IBM) rates, also age-adjusted to the standard 2000 US population, were calculated from the Surveillance Epidemiology and End Results (SEER) database. Tumor location was specified using ICD-O-3 codes C 160-C 169 with malignant behavior. Histopathology was specified using the ICD-O-3 code 9699. The rates were categorized by sex, age, race/ethnicity, and tumor stage at diagnosis. Age groups were older adults (aged 55 years or older) and younger adults (aged younger than 55 years). Race/ethnic groups included Non-Hispanic White (White), Non-Hispanic Black (Black), Hispanic, Non-Hispanic Asian/Pacific Islander (API), and Non-Hispanic American Indian/Alaska Native (AI/AN), as reported in the database. Stage at diagnosis included early stage (in situ and localized tumors) and late stage (regional and distant site tumors). Joinpoint Regression Software (version 5.0.2, NCI) using the weighted Bayesian Information Criteria method was used to generate time trends. Trends were reported as annual percentage change (APC) and average APC (AAPC). Parametric estimations were used with a two-sided t-test to evaluate the trends with a p-value cutoff at 0.05. RESULTS: There were 21,625 patients diagnosed with gastric MALT lymphoma in the US between 2001 and 2020. Overall, incidence rates were significantly decreasing over the study period (AAPC = -1.93). This decrease was seen in males (AAPC = -1.67) and in females (AAPC = -1.66) (Figure). When categorized by age groups, older adults also experienced a significant decrease in gastric MALT lymphoma incidence rates (AAPC = -1.66). While this was also seen in younger adults, the rates were decreasing at a slower pace (AAPC = -1.38). When categorizing the trends by race/ethnicity, incidence rates were significantly decreasing in White (AAPC = -2.09), Hispanic (AAPC = -1.61), and API (AAPC = -3.92) populations. However, the rates were stable among Blacks. While early-stage tumors experienced a significant decrease (AAPC = -1.10), the rates were stable for late-stage tumors. When evaluating mortality, there were 11,036 patients whose death was attributed to gastric MALT lymphoma between 2000 and 2020. IBM rates were decreasing in males (AAPC = -1.47), older adults (AAPC = -1.55), Whites (AAPC = -1.23), Hispanics (AAPC = -1.73), APIs (AAPC = -2.30), and early-stage tumors (AAPC = -1.08). On the other hand, IBM rates were stable in females, younger adults, Blacks, and late-stage tumors. DISCUSSION: An extensive nationwide data analysis encompassing nearly 98% of patients diagnosed with gastric MALT lymphoma in the US unveils a declining trend in the incidence of cancer overall over the past two decades. This decline is observed in both sexes and various age groups. When stratifying by race and ethnicity, this incidence has been decreasing in all populations except among Black individuals. While early-stage tumors have also demonstrated a significant decrease in incidence rates, late-stage tumors have shown no parallel decline. Mortality evaluation also revealed an improvement in most of the US population except among females, younger adults, Black individuals, and late-stage tumors. While the cause of our findings is unclear, it could be driven by disproportionate exposure to risk factors, including H. Pylori, and disparities in screening, management, and outcomes. Future studies are warranted to investigate factors contributing to worse outcomes of gastric MALT lymphoma, especially in the Black population.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue of the ileum in an adult presenting with intussusception: a case report and literature review.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (EMZL), also known as MALT lymphoma, is an extranodal multiorgan-invasive proliferative lymphoma composed of small B cells with variable morphology. It most commonly occurs in the digestive tract, with a high prevalence in the stomach, but EMZL originating in the small intestine is rare and lacks specificity in clinical manifestations, which makes it easy to be misdiagnosed. Herein, we report a rare case of small intestinal EMZL presentation as intussusception in a 32-year-old man. A colonoscopy performed at the local hospital revealed a pedicled polyp about 5 cm × 5 cm in size with a rough surface, and hyperemia was seen in the ileocecal region. He was admitted to our hospital for a polypectomy. A contrast-enhanced computed tomographic (CT) scan suggested ileocolic intussusception, which was subsequently confirmed by a colonoscopy in our hospital. Adult intussusception is relatively rare, with 90% of cases having a known causative mechanism and 40% of cases caused by primary or secondary malignancies. Therefore, we performed a laparoscopic-assisted right hemicolectomy for the patient. The resected specimen showed that the terminal ileum was intussuscepted into the ascending colon, and the intussusception was hyperemia and edema. A 2.5 cm × 2.5 cm × 1.5 cm mass was seen at the end of the intussusception. Postoperative pathology revealed that the mass was EMZL, partially transformed into a large B-cell lymphoma. The patient was transferred to the hematology department and completed a PET-CT showing postoperative manifestations of primary intestinal lymphoma, Lugano staging IE2. Although EMZL was an indolent lymphoma and the patient was in the early stages, the rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) regimen was given in view of the histological transformation. The patient is in regular follow-up. This was a rare case of small intestinal mass due to EMZL presented as intussusception in adults, which highlighted laparoscopic-assisted enterectomy as a potential therapeutic approach in the multidisciplinary collaborative therapy of small intestine EMZL.

A Rare Case of Primary Pulmonary Diffuse Large B-Cell Lymphoma Transformed from Marginal Zone Mucosa-Associated Lymphoid Tissue Lymphoma.

Primary pulmonary lymphoma is a rare neoplasm characterized by the proliferation of lymphoid tissue affecting the lungs. The most common subtype is marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT). Rarely, a MALT lymphoma transforms into a diffuse large B-cell lymphoma (DLBCL). Treatment options include chemotherapy, radiotherapy, immunotherapy, and surgery. Here, we describe a patient with a primary pulmonary MALT lymphoma transforming into DLBCL. The purpose of this case report is to raise awareness of the relevant clinical and imaging features and to emphasize the need for a multidisciplinary approach to optimal management. In addition, we screened the PubMed and Embase databases for similar reports with a confirmed presence of transforming lymphoma within the lungs.

A case of endobronchial mucosa-associated lymphoid tissue (MALT) lymphoma successfully treated with radiotherapy and a review of the literature.

A 60-year-old man was noted to have an elevated lesion in the right mainstem bronchus on chest computed tomography (CT) during his annual medical checkup 3 years previously. The lesion had gradually increased in size. FDG-PET showed no accumulation. Bronchoscopy revealed 5 nodular smooth surface protrusions on the ventral surface of the right mainstem bronchus, with the largest lesion that measured 5 mm in diameter. Biopsy showed diffuse infiltration of small lymphocytes, positive for CD20 and subsequently diagnosed with mucosa-associated lymphoid tissue (MALT) lymphoma. The lesions disappeared on chest CT after radiotherapy, and no recurrence has been observed after 5 years. We reviewed 48 cases of endobronchial MALT lymphoma in the literature and provided a comprehensive review of the literature to date including our case.

Study of individual domains contributing to MALT1 dimerization in BCL10-independent and dependent assembly.

The CARMA-BCL10-MALT1 (CBM) signalosome functions as a pivotal supramolecular module, integrating diverse receptor-induced signaling pathways to regulate BCL10-dependent NF-kB activation in innate and adaptive immunity. Conversely, the API2-MALT1 fusion protein in t(11; 18)(q21; q21) MALT lymphoma constitutively induces BCL10-independent NF-kB activation. MALT1 dimer formation is indispensable for the requisite proteolytic activity and is critical for NF-kB activation regulation in both scenarios. However, the molecular assembly of MALT1 individual domains in CBM activation remains elusive. Here we report the crystal structure of the MALT1 death domain (DD) at a resolution of 2.1 Å, incorporating reconstructed residues in previously disordered loops 1 and 2. Additionally, we observe a conformational regulation element (CRE) regulating stem-helix formation in NLRPs pyrin (PYD) within the MALT1 DD structure. The structure reveals a stem-helix-mediated dimer further corroborated in solution. To elucidate how the BCL10 filament facilitates MALT1 dimerization, we reconstitute a BCL10-CARD-MALT1-DD-IG1-IG2 complex model. We propose a N+7 rule for BCL10-dependent MALT1 dimerization via the IG1-IG2 domain and for MALT1-dependent cleavage in trans. Biochemical data further indicates concentration-dependent dimerization of the MALT1 IG1-IG2 domain, facilitating MALT1 dimerization in BCL10-independent manner. Our findings provide a structural and biochemical foundation for understanding MALT1 dimeric mechanisms, shedding light on potential BCL10-independent MALT1 dimer formation and high-order BCL10-MALT1 assembly.

A case of pulmonary primary MALT lymphoma with distinctive bronchoscopic findings.

Mucosa-associated lymphoid tissue (MALT) is a low-grade lymphoma, but cases in which it has transformed into a high-grade lymphoma have been reported, necessitating an accurate diagnosis. The patient was a 79-year-old nonsmoking Japanese female with history of ocular sarcoidosis. A computed tomography scan of her chest revealed a 35-mm nodule in the left S1 + 2, contiguous with the lymph nodes. Additional nodules were observed around the left B5 and B10a. Bronchoscopy revealed stenosis caused by a white, glossy, elevated lesion with angiogenesis at the orifice of the left upper lobe bronchus. The biopsy specimen demonstrated the dominance of lymphoid cells and tested positive for CD20, CD79a, Bcl-2, and IRTA-1, which is consistent with the findings in MALT lymphoma. Therefore, in the presence of multiple infiltrative shadows along the bronchi with glossy elevated lesions without necrosis on bronchoscopy, it is important to consider MALT lymphoma as a differential diagnosis.

Artificial intelligence-based differential diagnosis of orbital MALT lymphoma and IgG4 related ophthalmic disease using hematoxylin-eosin images.

PURPOSE: To investigate the possibility of distinguishing between IgG4-related ophthalmic disease (IgG4-ROD) and orbital MALT lymphoma using artificial intelligence (AI) and hematoxylin-eosin (HE) images. METHODS: After identifying a total of 127 patients from whom we were able to procure tissue blocks with IgG4-ROD and orbital MALT lymphoma, we performed histological and molecular genetic analyses, such as gene rearrangement. Subsequently, pathological HE images were collected from these patients followed by the cutting out of 10 different image patches from the HE image of each patient. A total of 970 image patches from the 97 patients were used to construct nine different models of deep learning, and the 300 image patches from the remaining 30 patients were used to evaluate the diagnostic performance of the models. Area under the curve (AUC) and accuracy (ACC) were used for the performance evaluation of the deep learning models. In addition, four ophthalmologists performed the binary classification between IgG4-ROD and orbital MALT lymphoma. RESULTS: EVA, which is a vision-centric foundation model to explore the limits of visual representation, was the best deep learning model among the nine models. The results of EVA were ACC = 73.3% and AUC = 0.807. The ACC of the four ophthalmologists ranged from 40 to 60%. CONCLUSIONS: It was possible to construct an AI software based on deep learning that was able to distinguish between IgG4-ROD and orbital MALT. This AI model may be useful as an initial screening tool to direct further ancillary investigations.

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue of the dura mimicking meningioma: a case report and literature review.

MALT lymphoma of the dura is a very rare type of low-grade B-cell lymphoma. Little more than 100 cases have been reported in the literature to date. We report a 43-year-old woman who was referred to hospital because of a series of three tonic-clonic seizures on the day of admission. Neurological examination revealed confusion and aphasia. Magnetic resonance imaging (MRI) showed a contrast-enhanced, broad-based lesion along the dura in the left parieto-occipital area. The suspicion of an en plaque meningioma was raised. The tumour invaded the brain parenchyma with visible extension into the brain sulci. There was a marked brain oedema surrounding the lesion and causing the midline shift 8 mm to the right. After stabilization of neurological condition (intravenous diuretics and steroids), the operation was performed. The diagnosis of dural MALT lymphoma was established. During the pathological examination, it was especially problematic to distinguish MALT lymphoma from follicular lymphoma, but the final diagnosis was MALT lymphoma. Surgical partial removal with additional R-CVP immunochemotherapy (rituximab, cyclophosphamide, vincristine and prednisone) resulted in complete remission. The follow-up period is 1 year. Our presented case of a MALT lymphoma highlights the fact that surgical partial removal with additional immunochemotherapy is an available option in these rare intracranial tumours.

Endoscopic ultrasound-guided fine needle biopsy diagnosis of circumferentially extraluminal mucosa-associated lymphoid tissue lymphoma in the transverse colon: a case report.

A 61-year-old man present to us with continued abdominal pain without abdominal tenderness for 1 month. Blood testing showed elevated biliary enzymes and inflammation. Contrast-enhanced computed tomography (CT) revealed thickening of the transverse colon with relatively strong enhancement but no bile duct dilatation. Colonoscopy revealed localized edema and granular mucosa in the transverse colon. Fluoroscopic endoscopy exhibited the absence of haustra. Multiple biopsies were performed, but differentiation between mild inflammation and mucosa-associated lymphoid tissue (MALT) lymphoma was inconclusive. To establish a definitive diagnosis, transgastric endoscopic ultrasound-guided fine needle biopsy of the hypoechoic mass was performed. Histopathological analysis exhibited the proliferation of small-sized lymphocytes. Fluorescence in situ hybridization revealed the characteristic API2-MALT1 translocation of MALT lymphoma. We performed liver biopsy to investigate biliary enzyme elevation. Histopathology confirmed lymphocytic infiltration within Glisson's capsule. Immunohistochemistry showed positive for CD20 and negative for CD3 and CD5, signifying the infiltration of MALT lymphoma in the liver. Based on these findings, we diagnosed MALT lymphoma, Lugano classification Stage IV. We performed bendamustine-rituximab (BR)-combined therapy. After six courses of BR-combined therapy, colonoscopy revealed improvement in the lead pipe sign and CT revealed disappearance of the mass.

Spontaneous regression and rare relapse after excisional biopsy in long-term observation of 31 patients with primary conjunctival lymphoma.

To elucidate long-term outcome in primary conjunctival lymphoma, a review was conducted of 31 consecutive patients: 21 men and 10 women with an age range of 28 to 85 (median, 61) years at presentation and follow-up periods ranging from 1 to 19 (median, 7) years. Conjunctival lymphoma was on the right side in 10 patients, on the left side in 12, and on both sides in 9. Upper, lower, or both fornix lesions in 28 patients were all diagnosed as extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), while thick nasal bulbar conjunctival lesions in 3 patients were differently diagnosed as MALT lymphoma, diffuse large B-cell lymphoma, and follicular lymphoma, respectively. Seven patients underwent local radiation (30 Gy): as initial treatment in 5 patients and treatment for relapse in 2 patients. The remaining 24 patients were observed without additional treatment after excisional biopsy: 5 of these 24 patients showed relapse 0.5 to 6 years later and underwent excisional biopsy again that revealed MALT lymphoma. Of the 5 patients with relapse, only one with second-time relapse underwent radiation. Fluorodeoxyglucose positron emission tomography was performed in 18 patients and showed no systemic lesions: high uptake was noted in the residual conjunctival lesions of 4 patients and in the relapsed conjunctival lesions of 3 patients. One patient died of rectal cancer while no patients died of lymphoma. Observation is an option in patients with primary conjunctival lymphoma after excisional biopsy. Radiation is a treatment option in the case of relapse.

Case report: Incidental MALT lymphoma of the left adrenal gland mimicking a metastatic spread within durvalumab maintenance treatment in inoperable stage III non-small cell lung cancer.

Durvalumab after chemotherapy in non-operable stage III non-small cell lung cancer (NSCLC) is the standard of care worldwide. We present a patient with the incidental discovery of a unilateral MALT lymphoma of the adrenal gland and adrenalitis during durvalumab maintenance treatment detected by 18F-FDG-PET/CT. We assessed the clinical and histopathological findings, radiological examinations and overall treatment. Our work emphasizes the significance of considering other differential diagnoses and the importance of multidisciplinary treatment of the findings, especially within clinical trials.

H pylori-Negative MALT-Associated Extranodal Marginal Zone Lymphoma: A Comprehensive Case Report and Literature Review.

Extranodal marginal zone B-cell lymphoma (ENMZL) of mucosa-associated lymphoid tissue (MALT), a rare subtype of B-cell lymphoma, is typically associated with Helicobacter pylori (H pylori) infection, especially in gastric cases. However, this article presents 2 unique cases of H pylori-negative colonic ENMZL, challenging the conventional understanding of the disease. The first case involves an 80-year-old male diagnosed with Stage 1E ENMZL in the descending colon, and the second describes a 74-year-old male with sigmoid colon ENMZL. Both cases lacked H pylori infection, adding complexity to their management. Accompanying these case studies is a comprehensive literature review, delving into the epidemiology, pathology, clinical features, diagnosis, and treatment of H pylori-negative ENMZL, with a focus on gastrointestinal involvement. This review highlights the importance of considering H pylori-negative cases in ENMZL diagnosis and management, illustrating the need for further research and individualized treatment approaches in this uncommon lymphoma subtype.

The role of baseline 2-[18 F]-FDG-PET/CT metrics and radiomics features in predicting primary gastric lymphoma diagnosis.

Diffuse Large B-Cell Lymphomas (DLCBL) and mucosa-associated lymphoid tissue (MALT) are the two most common primary gastric lymphomas (PGLs), but have strongly different features. DLBCL is more aggressive, is frequently diagnosed at an advanced stage and has a poorer prognosis. The aim of this retrospective study was to explore the role of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (2-[18 F]-FDG-PET/CT) and radiomics features (RFs) in predicting the final diagnosis of patients with PGLs. Ninety-one patients with newly diagnosed PGLs who underwent pre-treatment 2-[18 F]-FDG-PET/CT were included. PET images were qualitatively and semi-quantitatively analyzed by deriving maximum standardized uptake value body weight (SUVbw), maximum standardized uptake value lean body mass (SUVlbm), maximum standardized uptake value body surface area (SUVbsa), lesion to liver SUVmax ratio (L-L SUV R), lesion to blood-pool SUVmax ratio (L-BP SUV R), metabolic tumor volume (gMTV) and total lesion glycolysis of gastric lesion (gTLG), total MTV (tMTV), TLG, and first-order RFs (histogram-related and shape related). Receiver-operating characteristic (ROC) curve analyses were performed to determine the differential diagnostic values of PET parameters. The final diagnosis was DLBCL in 54 (59%) cases and MALT in 37 cases (41%). PGLs showed FDG avidity in 83 cases (90%), 54/54 of DLBCL and 29/37 of MALT. All PET/CT metabolic features, such as stage of disease and tumor size, were significantly higher in DLBCL than MALT; while the presence of H. Pylori infection was more common in MALT. At univariate analysis, all PET/CT metrics were significantly higher in DLBCL than MALT lymphomas, while among RFs only Shape volume_vx and Shape sphericity showed a significant difference between the two groups. In conclusion we demonstrated that 2-[18 F]-FDG-PET/CT parameters can potentially discriminate between DLBCL and MALT lymphomas with high accuracy. Among first-order RFs, only Shape volume_vx and Shape sphericity helped in the differential diagnosis.

Histological criteria for selecting patients who need clonality test for non-gastric MALT lymphoma diagnosis.

The histological diagnosis of extranodal marginal zone lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) is difficult for pathologists. Recently, digital pathology systems have been widely used to provide tools that can objectively measure lesions on slides. In this study, we measured the extent of marginal zone expansion in suspected MALT lymphoma cases and compared the results with those of a molecular clonality test. In total, 115 patients who underwent an IGH gene rearrangement test for suspected MALT lymphoma were included in this study. All cases were histologically classified into three patterns; "small lymphoid aggregates with no germinal center (Pattern 1)," "lymphoid follicles with germinal center (Pattern 2)" and " fused marginal zone or diffuse small lymphocytic proliferation (Pattern 3)." The proportions of monoclonality in Pattern 1, 2, and 3 were 25.0%, 55.0%, and 97.9%, respectively. The ratios of marginal zone thickness to germinal center diameter and entire lymphoid follicle area to germinal center area were measured in Pattern 2 cases using a digital pathology system. Combining the width cutoff of 1.5 and the areal cutoff of 3.5, the sensitivity, specificity, positive predictive value, and negative predictive value for MALT lymphoma were 96.97%, 70.37%, 80.00%, and 95.00%, respectively. In conclusion, through objective measurement of the marginal zone, suspected cases of MALT lymphoma requiring a molecular clonality test can be effectively selected.