API2-MALT1 fusion gene in colorectal lymphoma

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.

Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma in the Gastrointestinal Tract in the Modern Era

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) typically arises from sites such as the stomach, where there is no organized lymphoid tissue. Close associations between Helicobacter pylori and gastric MALT lymphoma or Campylobacter jejuni and immunoproliferative small intestinal disease (IPSID) have been established. A subset of tumors is associated with chromosomal rearrangement and/or genetic alterations. This disease often presents as localized disease, requiring diverse treatment approaches, from antibiotic therapy to radiotherapy and immunochemotherapy. Eradication therapy for H. pylori effectively cures gastric MALT lymphoma in most patients. However, treatment strategies for H. pylori-negative gastric MALT lymphoma are still challenging. In addition, the effectiveness of antibiotic therapy has been controversial in intestinal MALT lymphoma, except for IPSID. Endoscopic treatment has been noted to usually achieve complete remission in endoscopically resectable colorectal MALT lymphoma with localized disease. MALT lymphoma has been excluded from post-transplant lymphoproliferative disorders with the exception of Epstein–Barr virus (EBV)-positive marginal zone lymphoma (MZL). We also describe the expanding spectrum of EBV-negative MZL and a close association of the disease with the gastrointestinal tract.

Clinicopathologic Findings in Patients With Initial Diagnosis of Extranodal Marginal Zone B-Cell Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT) in Colorectal Mucosa

OBJECTIVES

To evaluate clinicopathologic features, management, and behavior of colorectal extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT).

METHODS

Clinical data, laboratory studies, and radiographic records were reviewed (2005-2018), and fluorescence in situ hybridization studies were performed.

RESULTS

Eleven patients were identified, six of whom were discovered as an incidental finding on endoscopy. Morphologic and immunophenotypic features were similar to MALT lymphomas at other sites except that lymphoepithelial lesions were uncommon. Three of nine patients were positive for BIRC3/MALT1 fusions, two of whom had identical B-cell clones identified in subsequent gastric biopsy specimens. Eight of 10 patients had no clinically evaluable disease after observation (±antibiotics; n = 4) or radiation/chemotherapy (n = 4).

CONCLUSIONS

Patients with incidental and localized colonic MALT lymphoma demonstrated an excellent prognosis with conservative management, although longer follow-up and data based on consistent staging and surveillance methods (including gastric evaluation) are necessary for informed management.

H. pylori infection alters repair of DNA double-strand breaks via SNHG17

Chronic infections can lead to carcinogenesis through inflammation-related mechanisms. Chronic infection of the human gastric mucosa with Helicobacter pylori is a well-known risk factor for gastric cancer. However, the mechanisms underlying H. pylori-induced gastric carcinogenesis are incompletely defined. We aimed to screen and clarify the functions of long noncoding RNAs (lncRNAs) that are differentially expressed in H. pylori-related gastric cancer. We found that lncRNA SNHG17 was upregulated by H. pylori infection and markedly increased the levels of double-strand breaks (DSBs). SNHG17 overexpression correlated with poor overall survival in patients with gastric cancer. The recruitment of NONO by overabundant nuclear SNHG17, along with the role of cytoplasmic SNHG17 as a decoy for miR-3909, which regulates Rad51 expression, shifted the DSB repair balance from homologous recombination toward nonhomologous end joining. Notably, during chronic H. pylori infection, SNHG17 knockdown inhibited chromosomal aberrations. Our findings suggest that spatially independent deregulation of the SNHG17/NONO and SNHG17/miR-3909/RING1/Rad51 pathways upon H. pylori infection promotes tumorigenesis in gastric cancer by altering the DNA repair system, which is critical for the maintenance of genomic stability. Upregulation of SNHG17 by H. pylori infection might be an undefined link between cancer and inflammation.

Anti-Helicobacter Pylori Therapy in Primary MALT Lymphoma of Rectum

Primary rectal MALT lymphoma is a very rare entity among extranodal MALT lymphomas and its therapeutic management has not been standardized. Different approaches including surgery, chemotherapy and radiotherapy have been proposed in the last decades. There have been reports on complete responses after anti-Helicobacter pylori therapy, also in patients without serological or histological evidence of Helicobacter pylori infection. In our patient we obtained a complete response with anti-Helicobacter pylori therapy and a disease-free survival of 34 months. Endoscopic ultrasound was useful for diagnosis and follow-up. Although the mechanisms that determined this response remain a matter of debate, anti-Helicobacter pylori therapy can be considered as first-line therapy in stage IE, nonbulky primary rectal MALT lymphoma. Endoscopic ultrasound could play a relevant role in the management of this rare condition.

GFusion: an Effective Algorithm to Identify Fusion Genes from Cancer RNA-Seq Data

Fusion gene derived from genomic rearrangement plays a key role in cancer initiation. The discovery of novel gene fusions may be of significant importance in cancer diagnosis and treatment. Meanwhile, next generation sequencing technology provide a sensitive and efficient way to identify gene fusions in genomic levels. However, there are still many challenges and limitations remaining in the existing methods which only rely on unmapped reads or discordant alignment fragments. In this work we have developed GFusion, a novel method using RNA-Seq data, to identify the fusion genes. This pipeline performs multiple alignments and strict filtering algorithm to improve sensitivity and reduce the false positive rate. GFusion successfully detected 34 from 43 previously reported fusions in four cancer datasets. We also demonstrated the effectiveness of GFusion using 24 million 76 bp paired-end reads simulation data which contains 42 artificial fusion genes, among which GFusion successfully discovered 37 fusion genes. Compared with existing methods, GFusion presented higher sensitivity and lower false positive rate. The GFusion pipeline can be accessed freely for non-commercial purposes at: https://github.com/xiaofengsong/GFusion .

Mucosa-associated lymphoid tissue (MALT) variant of primary rectal lymphoma: a review of the English literature

PURPOSE

Primary rectal lymphoma (PRL) is the third most common cause of rectal cancer following adenocarcinoma (90-95 %) and carcinoid (5 %). The most common variant of PRL is the mucosa-associated lymphoid tissue (MALT) type. To date, no study has been able to recommend an optimal treatment algorithm for this rare disease. The aim of our study was to review the English literature on primary rectal MALT lymphoma.

METHODS

A review of the English literature was conducted to identify articles describing the MALT variant of PRL.

RESULTS

Fifty-one cases were identified. A complete response was achieved in 12 of 19 cases treated with Helicobacter pylori eradication therapy, 5 of 6 with radiation, 2 of 4 cases with chemotherapy, 2 of 4 with endoscopic resection, 6 of 8 cases with surgical resection, and all 8 with combination therapies. Cases failing initial therapies were responsive to various second-line treatments. Two cases spontaneously regressed with observation alone.

CONCLUSION

Complete regression of primary rectal MALT lymphoma was achieved using various therapeutic strategies, although the numbers of different treatment modalities are too small to draw definitive conclusions.

Recent advances in intestinal lymphomas

A large variety of lymphoma types may develop as primary intestinal neoplasms in the small intestines or, less often, in the colorectum. Among these are a few entities such as enteropathy-associated T-cell lymphoma or immunoproliferative small intestinal disease that, essentially, do not arise elsewhere than in the gastrointestinal tract. In most instances the primary intestinal lymphomas belong to entities that also occur in lymph nodes or other mucosal sites, and may show some peculiar features. In the case of follicular lymphoma, important differences exist between the classical nodal cases and the intestinal cases, considered as a variant of the disease. It is likely that the local intestinal mucosal microenvironment is a determinant in influencing the pathobiological features of the disease. In this review we will present an update on the clinical, pathological and molecular features of the lymphoid neoplasms that most commonly involve the intestines, incorporating recent developments with respect to their pathobiology and classification. We will emphasize and discuss the major differential diagnostic problems encountered in practice, including the benign reactive or atypical lymphoid hyperplasias, indolent lymphoproliferative disorders of T or natural killer (NK) cells, and Epstein-Barr virus (EBV)-related lymphoproliferations.

Helicobacter pylori-Negative Primary Rectal MALT Lymphoma: Complete Remission after Radiotherapy

Rectal mucosa-associated lymphoid tissue (MALT) lymphoma is a rare condition. Although the majority of patients undergo surgical resection, a definitive treatment for rectal MALT lymphoma has not yet been established. In the present study, we report the outcome of radiotherapy in 3 patients with rectal MALT lymphoma. Our cohort ranged from 56 to 65 years of age. The male/female ratio was 1:2, and all patients were in stage I (Lugano classification) of the disease. Endoscopic findings revealed elevated lesions resembling submucosal tumors in 2 patients, and a sessile elevated lesion with a nodular surface in 1 patient. One of the 3 patients underwent magnifying endoscopy with crystal violet staining that demonstrated a type I pit pattern (Kudo's classification) lesion with a broad intervening area caused by the upthrust of the tumor from the submucosa. All patients tolerated radiotherapy at doses of 30 Gy without major complications and achieved complete remission. Follow-up ranged from 13 to 75 months (mean 51.0 months), revealing no recurrence of MALT lymphoma. As such, we propose radiotherapy to be a safe and effective means for treating rectal MALT lymphoma.

Regression of rectal mucosa-associated lymphoid tissue (MALT) lymphoma after antibiotic treatments

Only a few reports have described regression of rectal mucosa-associated lymphoid tissue (MALT) lymphoma after antibiotic treatment are generally found to be successful for gastric tumors. We examined eight rectal MALT lymphomas treated with antibiotic treatments to determine whether they regressed after treatment. We also discuss the relationship between rectal MALT lymphomas and MALT1 gene genetic abnormalities. Eight patients who had undergone antibiotic treatments were followed up with colonoscopy after initiation of the treatment. In five of the eight cases (63%) endoscopic examination showed that the rectal tumor had disappeared, which was confirmed histologically. Polymerase chain reaction for immunoglobulin heavy chain identified a monoclonal band in seven of eight cases (88%). Of the eight cases analyzed with fluorescence in situ hybridization (FISH) for MALT1 translocation, two demonstrated MALT1 gene genetic abnormality. These cases tended to be resistant to antibiotic treatment. Investigation and analysis of a large number of rectal MALT lymphomas are needed to establish suitable standards for antibiotic treatment.

Malt1 and cIAP2-Malt1 as effectors of NF-kappaB activation: kissing cousins or distant relatives?

Malt1 is a multi-domain cytosolic signaling molecule that was originally identified as the target of recurrent translocations in a large fraction of MALT lymphomas. The product of this translocation is a chimeric protein in which the N-terminus is contributed by the apoptosis inhibitor, cIAP2, and the C-terminus is contributed by Malt1. Early studies suggested that Malt1 is an essential intermediate in antigen receptor activation of NF-kappaB, and that the juxtaposition of the cIAP2 N-terminus and the Malt1 C-terminus results in deregulation of Malt1 NF-kappaB stimulatory activity. Initial experimental data further suggested that the molecular mechanisms of Malt1- and cIAP-Malt1-mediated NF-kappaB activation were quite similar. However, a number of more recent studies of both Malt1 and cIAP2-Malt1 now reveal that these proteins influence NF-kappaB activation by multiple distinct mechanisms, several of which are non-overlapping. Currently available data suggest a revised model in which cIAP2-Malt1 induces NF-kappaB activation via a mechanism that depends equally on domains contributed by cIAP2 and Malt1, which confer spontaneous oligomerization activity, polyubiquitin binding, proteolytic activity, and association with and activation of TRAF2 and TRAF6 at several independent binding sites. By contrast, emerging data suggest that the wild-type Malt1 protein uniquely contributes to NF-kappaB activation primarily through the control of two proteolytic cleavage mechanisms. Firstly, Malt1 directly cleaves and inactivates A20, a negative regulator of the antigen receptor-to-NF-kappaB pathway. Secondly, Malt1 interacts with caspase-8, inducing caspase-8 cleavage of c-FLIP(L), initiating a pathway that contributes to activation of the I kappaB kinase (IKK) complex. Furthermore, data suggest that Malt1 plays a more limited and focused role in antigen receptor activation of NF-kappaB, serving to augment weak antigen signals and stimulate a defined subset of NF-kappaB dependent responses. Thus, the potent activation of NF-kappaB by cIAP2-Malt1 contrasts with the more subtle role of Malt1 in regulating specific NF-kappaB responses downstream of antigen receptor ligation.

Translocation t(11;18)(q21;q21) in gastric B-cell lymphomas

Translocation t(11;18)(q21;q21) is the most frequent chromosomal aberration reported in gastric mucosa-associated lymphoid tissue (MALT) lymphomas. Intriguingly, this translocation has been reported only rarely in diffuse large B-cell lymphomas; it has been proposed that t(11;18)-positive tumors rarely progress to diffuse large B-cell lymphomas. We examined the frequency of chromosomal translocation t(11;18)(q21;q21) in mucosa-associated lymphoid tissue lymphoma and diffuse large B-cell lymphoma of the stomach. Paraffin-embedded tissues from patients with gastric B-cell lymphomas were selected retrospectively. The presence of the t(11;18)(q21;q21) was determined using reverse transcriptase-polymerase chain reaction and/or fluorescence in situ hybridization. beta-Actin transcript was also determined to evaluate the integrity and efficiency of RNA (cDNA) recovery from paraffin-embedded tissues. We analyzed 53 gastric B-cell lymphomas (33 diffuse large B-cell and 20 mucosa-associated lymphoid tissue) obtained from Italy, the USA, or Japan. Beta-actin transcript was amplified in 50 cases (94%), including 19 mucosa-associated lymphoid tissue and 31 diffuse large B-cell lymphomas (five with mucosa-associated lymphoid tissue components). The t(11;18) translocation was detected in 19% (6 of 31) cases with diffuse large B-cell lymphoma versus 26% (five of 19) with mucosa-associated lymphoid tissue lymphoma (P = 0.72). One of five diffuse large B-cell lymphomas with a mucosa-associated lymphoid tissue component showed the t(11;18)(q21;q21). In conclusion, translocation t(11;18)(q21;q21) was found in both mucosa-associated lymphoid tissue lymphomas and diffuse large B-cell lymphomas of the stomach at approximately equivalent frequencies; its presence does not exclude progression to diffuse large B-cell lymphoma.

Methylation and API2/MALT1 fusion in colorectal extranodal marginal zone lymphoma

Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) is rarely found in the large intestine. Because of its rarity, the underlying epigenetic and genetic changes in the pathogenesis and prognostic factors have yet to be well established. For this purpose, methylation profiles and API2/MALT1 fusion in marginal zone B-cell lymphoma of MALT in the colorectum were studied and compared with treatment outcomes. For methylation analyses, 7 independent CpG islands (p15, p16, DAP kinase, hMLH1, MINT1, MINT2, and MINT31) were examined and RT-PCR for detection of API2/MALT1 fusion transcripts were performed in 15 colorectal marginal zone B-cell lymphoma of MALT in a single institution. Marginal zone B-cell lymphomas of MALT from both gastric and colorectal locations were also examined. In methylation analyses (n=13), 8 of 13 (62%) cases were classified as CIMP (CpG island methylator phenotype)-positive. Methylation was more frequently observed in cases with advanced disease stages than with earlier stages; an average of two methylated loci for earlier stages (IE or IIE) versus four loci in advanced ones (IVE; P=0.02). The estimated 5-year progression-free survival was 42% for CIMP-positive and 100% for CIMP-negative cases (P=0.03). API2/MALT1 fusion transcripts were found in two of nine cases (22%). In two cases with concurrent gastric and colorectal involvement of marginal zone B-cell lymphoma of MALT, methylation patterns and API2/MALT1 fusion results were different by location. Our results suggest that methylation profiles define a clinically more aggressive subgroup and multiclonal origin for marginal zone B-cell lymphoma of MALT with multiorgan involvement.

The rectal tonsil: a reactive lymphoid proliferation that may mimic lymphoma

The rectal tonsil (RT), a localized reactive proliferation of lymphoid tissue occurring in the rectum, can cause diagnostic difficulty; and awareness of this entity can prevent a misdiagnosis of lymphoma. A clinicopathologic analysis of 11 cases of RT was performed to determine the features that can aid in the recognition of this entity. The patients (6 males and 5 females) were middle-aged adults, except for 1 case affecting a young boy (age range, 1 to 62 y; mean, 49 y). All presented with either rectal bleeding or abdominal pain, or had the lesion found on routine screening. Endoscopic descriptions, available in all cases, reported a raised, polypoid lesion in 8 cases, a nodule in 2 cases, and a "mass" in 1 case. Histologically, all cases were composed of a lymphoid proliferation involving the lamina propria or submucosa. Lymphoid follicles could be identified in all cases, although some were difficult to appreciate without immunostains for follicular dendritic cells. Five cases showed overlying cryptitis and mild architectural distortion, but no cases showed crypt obliteration or crypt abscesses. Intraepithelial lymphocytes were present in 9 cases, and 5 cases showed nondestructive lymphoepithelial lesions. During a mean follow-up of 5.8 years, none showed a recurrence or developed lymphoma. In conclusion, RT, with its distinctive features, is an important entity to recognize. Familiarity with the range of histologic features characteristic of the RT is critical in avoiding misinterpretation as lymphoma.

Clinical features and prognosis of gastric MALT lymphoma with special reference to responsiveness to H. pylori eradication and API2-MALT1 status

BACKGROUND AND AIM

Clinicopathologic characteristics and prognosis of Helicobacter pylori eradication-resistant gastric MALT lymphoma have not been well clarified. We analyzed a consecutive series of gastric MALT lymphomas at our institution regarding treatment, clinical course, and prognosis, with special reference to responsiveness to H. pylori eradication and presence of API2-MALT1.

METHODS

Subjects were 92 consecutive patients with gastric MALT lymphoma. Seventy were H. pylori positive, and 87 received H. pylori eradication therapy. The remaining five cases were API2-MALT1 positive and did not receive eradication treatment. Second-line treatments were radiation therapy, total gastrectomy, and chemotherapy (rituximab, rituximab plus CHOP, or rituximab plus 2-chlorodeoxyadenosine).

RESULTS

Gastric MALT lymphoma was classified into three groups, except one case with API2-MALT1 who responded to H. pylori eradication therapy: responders without API2-MALT1 (group A, N = 56, 65%), nonresponders without API2-MALT1 (group B, N = 16, 19%), and nonresponders with API2-MALT1 (group C, N = 14, 16%). Most cases in group A attained complete remission (CR) in 2 or 3 months and CR persisted for an average of 51.1 months (3-134 months). Recurrence was only seen in one case. In groups B and C, radiation therapy, chemotherapy, and total gastrectomy resulted in CR in 13, 5, and 2 cases, respectively. In 5 group B patients and 6 group C patients who did not undergo second-line therapy, disease did not progress for an average of 10.4 and 40.1 months, respectively. In 1 group C case who did not receive second-line treatment, lymphoma metastasized to the lung 12 yr after eradication. All group B patients and all but 2 group C patients remain alive; one of these deaths was from gastric carcinoma developing 7 yr after eradication.

CONCLUSION

Gastric MALT lymphoma responding to H. pylori eradication demonstrated good prognosis, and for nonresponsive cases, second-line treatments resulted in CR. However, careful observation for development of gastric carcinoma and disease progression is essential during follow-up of API2-MALT1-positive MALT lymphoma when patients decline second-line treatment.

Mucosa-associated lymphoid tissue lymphoma: molecular pathogenesis and clinicopathological significance

Mucosa-associated lymphoid tissue (MALT) lymphoma is a low-grade tumor closely associated with chronic inflammation such as that of Helicobacter pylori gastritis, Sjogren's syndrome, and Hashimoto's thyroiditis. Tumor regression by H. pylori eradication alone is well known in gastric MALT lymphoma, but some tumors occur in the absence of pre-existing chronic inflammation. The understanding of MALT lymphoma biology has significantly improved, and recurrent cytogenetic alterations have been detected. These include the trisomies 3 and 18, and the translocations t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21), and t(3;14)(p14.1;q32). At least some of these alterations result in the constitutive activation of the nuclear factor (NF)-kappaB pathway, and may exert anti-apoptotic action. Apoptosis inhibitor 2-MALT lymphoma-associated translocation 1 (API12-MALT1) fusion, resulting from t(11;18)(q21;q21), is specific to, and is the most common in, MALT lymphomas, and its clinicopathological significance has been studied extensively. The focus of the present review is on the recent progress made in elucidating MALT lymphomagenesis and its clinicopathological impact, especially in terms of the effect of API2-MALT1 fusion on this unique tumor.

Successful radiotherapy in a patient with primary rectal mucosa-associated lymphoid tissue lymphoma without the API2-MALT1 fusion gene: a case report and review of the literature

Primary rectal MALT lymphoma is rare comprising less than 1% of MALT lymphomas. A 26-year-old man was referred to our hospital because of constipation and abdominal fullness. Colonoscopy revealed multiple submucosal tumors in rectum. Histopathological examination showed dense proliferation of small lymphoid cells, but lymphoepithelial lesions were not observed. The cells were CD5(-), CD10(-), CD20(+) and cyclinD1(-). The patient was diagnosed as having MALT lymphoma. The patient was negative for API2-MALT1 gene, and radiotherapy was performed and CR was achieved. With the accumulation of cases, establishment of a treatment strategy for primary rectal MALT lymphoma is expected in the future.

A dual role for the API2 moiety in API2-MALT1-dependent NF-kappaB activation: heterotypic oligomerization and TRAF2 recruitment

Mucosa-associated lymphoid tissue (MALT) lymphoma is the most common extranodal lymphoid neoplasm. Chromosomal translocation t(11;18)(q21,q21) is found in 30% of gastric MALT lymphomas and is associated with a failure to respond to standard treatment and a tendency to disseminate. This translocation generates a chimeric protein composed of N-terminal sequences of Inhibitor of Apoptosis 2 (API2, also known as BIRC3 and cIAP2) fused to C-terminal sequences of MALT1. API2-MALT1 promotes cell survival and proliferation via activation of nuclear factor-kappaB (NF-kappaB). Here, we investigate the mechanism by which the API2 moiety contributes to NF-kappaB stimulation. We find that the API2 moiety mediates oligomerization of API2-MALT1 as well as interaction with tumor necrosis factor receptor-associated factor 2 (TRAF2). Surprisingly, oligomerization does not occur via homotypic interaction; rather, the API2 moiety of one monomer interacts with the MALT1 moiety of another monomer. Further, the specific region of the API2 moiety responsible for mediating oligomerization is distinct from that mediating TRAF2 binding. Although deletion or mutation of the TRAF2 binding site does not inhibit oligomerization, it does lead to dramatically decreased NF-kappaB activation. Deletion of both TRAF2 binding and oligomerization regions results in near-complete loss of NF-kappaB activation. Thus, API2 moiety-mediated heterotypic oligomerization and TRAF2 binding both contribute to maximal API2-MALT1-dependent NF-kappaB stimulation.

Follicular lymphoma frequently originates in the salivary gland

The aim of the present study was to examine the clinicopathological presentations of follicular lymphomas (FL) of the salivary glands, as compared to mucosa-associated lymphoid tissue (MALT) lymphomas. A total of 27 primary salivary gland lymphomas were examined: 6 FL (five, grade 1; one, grade 2); 19 MALT lymphomas; and two diffuse large B-cell lymphomas. The FL patients ranged in age from 24 to 73 years, with a mean of 49 years, which was younger than that of MALT patients (mean: 64 years; P < 0.05). Four of the six FL arose from the submandibular gland, which was the origin of only five out of a total of 19 MALT lymphomas. One FL patient was in clinical stage (CS) IE, two in CS IIE, and two in CS III and IV. As regards the MALT lymphoma patients, 13 (68%) were in CS IE and five (26%) in CS IIE. None of the FL patients had clinical diagnosis of autoimmune disease but eight MALT lymphoma patients had autoimmune disease. The present study found a relatively high incidence of FL in the salivary glands. The observed differences in age of onset, background of autoimmune disease, and lesion site suggests that the pathogenesis of FL may differ from that of MALT lymphoma.

Deviated VH4 immunoglobulin gene usage is found among thyroid mucosa-associated lymphoid tissue lymphomas, similar to the usage at other sites, but is not found in thyroid diffuse large B-cell lymphomas

It remains unclear whether or not diffuse large B-cell lymphomas of extranodal sites arise from mucosa-associated lymphoid tissue (MALT) lymphomas. We studied the clinicopathological features of MALT lymphoma and diffuse large B-cell lymphoma in the thyroid gland, with special reference to VH usage of immunoglobulin gene rearrangement, to clarify the relationships between these two types of lymphomas. In addition, t(11; 18) (q21; q21) translocation was examined by multiplex reverse transcription-polymerase chain reaction. We examined 58 patients with primary thyroid lymphoma: 31 (male seven and female 24) with MALT lymphoma and 27 (male three and female 24) with diffuse large B-cell lymphoma. Interestingly, the sequence of VH genes revealed that the two subtypes differed significantly in their use of the VH4 family (P < 0.05). Of the seven MALT lymphomas, three used the VH4 family and the other four used the VH3 family, whereas eight out of nine diffuse large B-cell lymphoma used the VH3 family, one used the VH1 family, and none used the VH4 family. It was also interesting that, in one diffuse large B-cell lymphoma patient with MALT lymphoma, the diffuse large B-cell lymphoma component used the VH3 family and the MALT lymphoma component used the VH4 family. These data imply that, in a subset of cases, these two subtypes do not share a common origin and that at least some diffuse large B-cell lymphomas have a de novo origin. No t(11; 18) (q21; q21) was detected in thyroid lymphomas, which are different from MALT lymphoma of the stomach, lungs, large intestine and ocular adnexa. This strongly indicated that the presence of t(11; 18) (q21; q21) in MALT lymphoma is organ-specific.

Detection of BCL2-IGH rearrangement on paraffin-embedded tissue sections obtained from a small submucosal tumor of the rectum in a patient with recurrent follicular lymphoma

A 59-year-old woman was admitted to our hospital because of recurrent follicular lymphoma (FL). Colonoscopic examination revealed a rectal submucosal tumor (SMT) without any erosions and ulcers. In this patient, it was difficult to distinguish non-Hodgkin’s lymphoma (NHL) invasion from other disorders of the colon including carcinoid tumor merely based on endoscopic findings. Histopathologic and immunohistochemical studies on biopsy specimens showed an infiltration of atypical lymphocytes that were positive for CD20 and BCL2 but negative for UCHL-1. Fluorescence in situ hybridization on paraffin-embedded tissue sections (T-FISH) identified a translocation of BCL2 with IGH gene. Based on these findings, the tumor was defined as an invasion of FL. T-FISH method is useful for the detection of a monoclonality of atypical lymphocytes in an SMT of the gastrointestinal tract, and particularly for the detection of chromosomal translocations specific to lymphoma subtypes.