Mucoepidermoid carcinoma is the most common primary malignancy of the salivary gland. We and others showed that CRTC1-MAML2 gene fusion was associated with favorable clinicopathological tumor features. Recently, a novel gene fusion, CRTC3-MAML2, was reported as a rare gene alteration in a case of mucoepidermoid carcinoma. However, its frequency and clinicopathological significance remains unclear. In all, 101 cases of mucoepidermoid carcinoma and 89 cases of non-mucoepidermoid carcinoma of the salivary gland were analyzed, and RNA was extracted from formalin-fixed, paraffin-embedded specimens. In the CRTC family, there have been three genes, CRTC1, CRTC2, and CRTC3. We developed reverse transcriptionpolymerase chain reaction (RT-PCR) assays for CRTC1-MAML2, CRTC2-MAML2, and CRTC3-MAML2 fusions. Clinicopathological data of the patients were obtained from their clinical records. Of 101 cases of mucoepidermoid carcinoma, 34 (34%) and 6 (6%) were positive for CRTC1-MAML2 and CRTC3-MAML2 fusion transcripts. However, in the 89 cases of non-mucoepidermoid carcinoma, neither transcript was noted. In the former cases, CRTC1-MAML2 and CRTC3-MAML2 fusions were mutually exclusive. The other fusion, CRTC2-MAML2, was not detected. We confirmed that the clinicopathological features of CRTC1-MAML2-positive mucoepidermoid carcinomas indicated an indolent course. CRTC3-MAML2-positive mucoepidermoid carcinomas also had clinicopathologically favorable features; all cases showed a less advanced clinical stage, negative nodal metastasis, no high-grade tumor histology, and no recurrence or tumor-related death after surgical resection of the tumor. It is interesting to note that patients with CRTC3-MAML2-positive tumors (mean 36 years of age) were significantly younger that those with the CRTC1-MAML2 fusion (55 years) and those with fusionnegative tumors (58 years). In conclusion, CRTC3-MAML2 fusion, which is mutually exclusive with CRTC1-MAML2 fusion and specific to mucoepidermoid carcinoma, may be detected more frequently than previously expected. Mucoepidermoid carcinomas possessing CRTC3-MAML2 fusion may be associated with favorable clinicopathological features and patients may be younger than those with CRTC1-MAML2 fusion or those with no detectable gene fusion. Keywords: mucoepidermoid carcinoma; CRTC3-MAML2 fusion; clinicopathological study; prognosis Mucoepidermoid carcinoma, representing 5% of all salivary gland tumors and 20% of the malignant forms, is the most frequent primary malignancy of the salivary gland in both adults and children.

The results suggested that the evaluation of Ki-67 expression in KCOT at the time of pathological diagnosis might be helpful for consideration of appropriate adjunctive surgical procedures to avoid a recurrence and may serve as a prognostic marker.

The majority of gastric mucosa-associated lymphoid tissue (MALT) lymphomas are successfully treated with Helicobacter pylori eradication alone. However, certain subsets of these tumors are resistant to the eradication treatment. As API2-MALT1 fusion is a feature of one of these subsets, we divided gastric MALT lymphomas into three groups: eradication-responsive and API2-MALT1 fusion-negative (Group A), eradication-resistant and fusion-negative (Group B), and eradication-resistant and fusion-positive (Group C). To characterize further gastric MALT lymphomas, we analyzed VH genes, which do not change in the course of tumor progression, by extensive subcloning of the monoclonal PCR products of 45 cases. VH3-23 and VH3-30 were preferentially used in Group A tumors (14/23 cases, 61%) as compared with Group B (1/10 cases, 10%, P ¼ 0.0094) and Group C (2/ 12 cases, 17%, P ¼ 0.017). Tumors of Groups B and C used variegated VH fragments, and no dominant VH fragments were noted. Somatic mutation was detected in most of the cases. Ongoing mutation was detected in 3/45 cases (7%), when assessed according to strict criteria for a confirmed mutation. These findings suggest that inflammation-dependent tumors (Group A) may be derived from a highly restricted, probably H. pyloriassociated, B cell subset and may not often progress to those that are inflammation-independent (Groups B and C). Although considered to be common in this tumor, ongoing mutation may be infrequent when assessed by strict criteria. Keywords: gastric MALT lymphoma; helicobacter pylori; eradication; immunoglobulin heavy chain variable genes; API2-MALT1 fusion gene Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) is a distinct low-grade lymphoma, which is typically localized long term at the site of origin. 1 A preexisting chronic inflammation, such as Helicobacter pylori gastritis, Hashimoto's thyroiditis, or Sjogren's syndrome is considered to influence significantly its development. 1 The etiological link between gastric MALT lymphoma and H. pylori gastritis has arisen from the fact that the majority of gastric MALT lymphomas (approximately 70% of cases) show complete regression on eradication of H. pylori alone. 2 API2-MALT1 fusion, cloned from t(11;18)(q21;q21), is a gene alteration specific to MALT lymphomas. 3,4 API2 is a member of the IAP (inhibitor of apoptosis) gene family, and is essential for the suppression of apoptosis. 5 MALT1, a novel