[A case of a collision tumor comprising mucosa-associated lymphoid tissue lymphoma and early gastric cancer].

A 60-year-old woman underwent upper gastrointestinal endoscopy for an abnormality identified during routine examination. The lower gastric corpus showed a type 0-I elevated lesion with a faded mucosa and an area of converging mucosal folds in contact with the lesion. Biopsy indicated the former to be a high-grade adenoma and the latter to be a mucosa-associated lymphoid tissue (MALT) lymphoma. At the same time, Helicobacter pylori infection was diagnosed. Eradication therapy was administered to manage the MALT lymphoma; this resulted in improvement after 3 months. Endoscopic submucosal dissection was performed for the elevated lesion, and subsequent histopathology showed contact between the MALT lymphoma and gastric cancer. Therefore, the patient was diagnosed with a collision tumor. Concurrent cancers are increasingly reported and should be considered during examination.

[Primary diffuse large B-cell lymphoma of the uterus complicated with hydronephrosis].

Malignant lymphoma sometimes originates from extranodal sites; however, the uterus has rarely been reported as the site of the primary lesion. We present a patient with malignant lymphoma of the uterus complicating bilateral hydronephrosis. A 67-year-old previously healthy woman was seen at a clinic because of massive genital bleeding. She was referred to our hospital for further examination of a uterine tumor. Computed tomography scans revealed a pelvic tumor invading to the retroperitoneal region, which caused bilateral obstruction of the ureters and hydronephrosis. No lymph node swelling was detected. Magnetic resonance imaging showed a bulky uterine tumor that was homogenously low on T1-weighted imaging and isointense on T2-weighted imaging, while the endometrium was intact. A pathological examination of the biopsy specimen from the uterine cervix revealed diffuse infiltration of CD20-positive atypical large lymphoid cells, which was compatible with diffuse large B-cell lymphoma (DLBCL). Since the tumor expanded from the uterus and no other abnormal lesion was observed in imaging studies including gallium scintigraphy, a diagnosis of DLBCL of the uterus, clinical stage IE was made. The patient received six cycles of rituximab plus CHOP chemotherapy followed by involved field irradiation. She achieved complete remission and has been alive for more than two years without relapse.

Use of endoscopic ultrasound-guided fine needle aspiration of the pancreas to diagnose a case of primary linitis plastica of the colon with retroperitoneal dissemination.

A 54-year-old man had previously undergone curative sigmoidectomy for poorly differentiated adenocarcinoma with a signet-ring cell component of the sigmoid colon, which was characterized morphologically by stenosis and inelasticity of the colon (linitis plastica). Six weeks after surgery, the patient developed stenosis of the right ureter. Disseminated sigmoid cancer was suspected, and chemotherapy was started. Nine months after initiation of chemotherapy, obstructive jaundice was observed which was due to stenosis of the distal bile duct (BD). Although computed tomography showed no evident metastatic lesion that could cause the stenosis, swelling of the entire pancreas was evident compared to that of 11 months earlier. Endoscopic ultrasound (EUS) also did not detect any focal masses in the head of the pancreas, although there was a diffuse hypoechoic change in the entire pancreas. Histopathology of the stenotic BD and biopsy specimen from the head of the pancreas showed no malignant cells. Two months after the initial endoscopic bile duct drainage, the patient was admitted again for epigastric pain. A second EUS fine needle aspiration (EUS-FNA) of the head of the pancreas was performed and showed poorly differentiated carcinoma with some signet-ring cells. This finding provided histological confirmation of a disseminated pancreatic lesion of the previously resected linitis plastica of the sigmoid colon. This is a rare case of disseminated pancreatic lesion from primary linitis plastica of the colon diagnosed by EUS-FNA.

Mediastinal Yolk Sac Tumor Producing Protein Induced by Vitamin K Absence or Antagonist-II.

Extragonadal yolk sac tumors (YSTs) are rare. We herein report the case of a 66-year-old man with mediastinal, lung and liver tumors. The largest mass was located in the liver and contained a high concentration of protein induced by vitamin K absence or antagonist-II (PIVKA-II) and alpha-fetoprotein. Therefore, the lesion was difficult to distinguish from hepatocellular carcinoma. Finally, YST was diagnosed based on the results of a liver biopsy. Although chemotherapy was effective, the patient died of respiratory failure. The autopsy revealed primary mediastinal YST. In the current report, we describe this case of PIVKA-II-producing YST and review previous cases of PIVKA-II-producing tumors other than hepatoma.

A Screen for Epigenetically Silenced microRNA Genes in Gastrointestinal Stromal Tumors.

BACKGROUND: Dysregulation of microRNA (miRNA) has been implicated in gastrointestinal stromal tumors (GISTs) but the mechanism is not fully understood. In this study, we aimed to explore the involvement of epigenetic alteration of miRNA genes in GISTs. METHODS: GIST-T1 cells were treated with 5-aza-2'-deoxycytidine (5-aza-dC) and 4-phenylbutyric acid (PBA), after which miRNA expression profiles were analyzed using TaqMan miRNA arrays. DNA methylation was then analyzed using bisulfite pyrosequencing. The functions of miRNAs were examined using MTT assays, wound-healing assays, Boyden chamber assays and Matrigel invasion assays. Gene expression microarrays were analyzed to assess effect of ectopic miRNA expression in GIST-T1 cells. RESULTS: Of the 754 miRNAs analyzed, 61 were significantly upregulated in GIST-T1 cells treated with 5-aza-dC plus PBA. Among those, 21 miRNA genes were associated with an upstream CpG island (CGI), and the CGIs of miR-34a and miR-335 were frequently methylated in GIST-T1 cells and primary GIST specimens. Transfection of miR-34a or miR-335 mimic molecules into GIST-T1 cells suppressed cell proliferation, and miR-34a also inhibited migration and invasion by GIST-T1 cells. Moreover, miR-34a downregulated a number of predicted target genes, including PDGFRA. RNA interference-mediated knockdown of PDGFRA in GIST-T1 cells suppressed cell proliferation, suggesting the tumor suppressive effect of miR-34a is mediated, at least in part, through targeting PDGFRA. CONCLUSIONS: Our results suggest that miR-34a and miR-335 are candidate tumor suppressive miRNAs in GISTs, and that they are frequent targets of epigenetic silencing in GISTs.