Shinobu Yamada

Very low incidence of microsatellite instability in intraductal papillary-mucinous neoplasm of the pancreas

Intraductal papillary‐mucinous carcinoma (IPMC) of the pancreas, a new entity of pancreatic cancer with a favorable prognosis, has shown a gradual increase in the number of reported cases. Patients with high‐frequency microsatellite instability (MSI‐H) tumors have been shown to survive longer than those with low‐frequency MSI (MSI‐L) or microsatellite stable (MSS) tumors in colorectal and gastric cancer. We investigated whether MSI‐H in patients with IPMC can contribute to a good prognosis. The formalin‐fixed paraffin‐embedded tumors and surrounding normal pancreatic tissues from 10 patients with IPMCs and 16 with intraductal papillary‐mucinous adenomas (IPMAs) were provided for DNA extraction after microdissection. Polymerase chain reaction (PCR) was carried out using 8 microsatellite primer marker sets. The mixed PCR samples were analyzed using a genetic analyzer. MSI‐H was determined by assessment of microsatellite variations in 3 or more of the 8 tested markers. Immunohistochemical staining of the MSI‐responsible proteins hMLH1 and hMSH2 was conducted for both the IPMC and IPMA samples. Ten percent of IPMC harbored MSI‐H tumors, whereas no MSI‐H tumors were detected in the IPMAs. Thirty percent of IPMC tumors and 25% of IPMA tumors showed MSI‐L. All IPMCs and IPMAs showed normal expression of both hMLH1 and hMSH2. MSI‐H and loss of hMLH1 and hMSH2 are very rare events in both IPMCs and IPMAs. We conclude that a good prognosis for patients with IPMC is not associated with MSI‐H.

Lymphangioma of the Lesser Omentum Associated with Abdominal Esophageal Carcinoma: Report of a Case

Abstract A case of lymphangioma of the lesser omentum associated with abdominal esophageal carcinoma is described herein. The patient was a 54-year-old man who initially presented with dysphagia. Gastrointestinal fiberscopy (GIF) revealed an esophageal carcinoma and abdominal computed tomography (CT) detected a 3-cm, low-density lesion on the median aspect of the fornix, which was diagnosed as a metastatic lymph node. A radical operation was performed to resect the esophageal carcinoma, and a cystic lesion the size of a hens egg was found in the lesser omentum of the stomach. The cystic lesion, which contained serous fluid, was unilocular and attached to the serosa of the stomach. The histological diagnosis was omental lymphangioma. Our review of the Japanese literature revealed 29 cases of lesser omental lymphangioma, but only two of these were associated with an advanced malignant tumor. Although the etiology of omental lymphangioma is unclear, the findings in our case suggested that obstruction of the lymphatic vessels invaded by the esophageal carcinoma may be one of the causes of this disease.

A novel high-specificity approach for colorectal neoplasia: Detection of K-ras2 oncogene mutation in normal mucosa.

There is an important need for a high‐specificity approach to colorectal cancer. Approximately 50% of colorectal tumors contain K‐ras gene mutations, which occur as an early step in carcinogenesis. K‐ras mutations were detectable not only in tumors but also in microscopically normal colorectal mucosa close to carcinomas in some patients with colorectal cancer. This is the first systematic analysis of K‐ras mutations in normal colonic mucosa at multiple consistently‐selected locations. A total of 480 normal colonic mucosal samples were obtained from 80 subjects, including 65 patients with sporadic colorectal cancer and 15 controls in whom a colorectal neoplasm was ruled out endoscopically. Normal mucosal samples were obtained at multiple consistently‐selected locations using biopsy forceps during colonoscopy. Mutant allele‐specific amplification (MASA)‐PCR was performed; this could detect a K‐ras mutation in normal colonic mucosa even though it was only sparsely present. The K‐ras mutation was found in histologically normal mucosa from colorectal cancer patients (20 of 65 cases; 41 of 390 loci) by MASA‐PCR, especially frequent (51%; 19 of 37 cases) when the tumor showed a K‐ras mutation. In contrast, no mutation was found in normal mucosa from 15 controls (90 loci). K‐ras mutation in normal mucosa showed a significant association with the presence of colorectal cancer (p = 0.008). The specificity of the MASA‐PCR method for colorectal neoplasms was thus 100%. We conclude that detection of K‐ras mutations in normal colonic mucosa might serve as a high‐specificity approach to colorectal cancer.

A Case Report of Hepatocellular Carcinoma Associated with Sarcoid Reaction in Regional Lymph Nodes

症例は67歳の男性で, 10年前よりC型慢性肝炎にて通院中, 2003年8月腰背部痛が出現したため当院を受診した. AFPが60ng/mlと高値で, 腹部USにて肝S5に4cm大の高エコー腫瘍を認めた. 造影CTでは辺縁のみ造影され, 総肝動脈, 下大静脈周囲リンパ節腫大もみられた.上部・下部消化管に癌病変なく, 肺・縦隔にも異常所見はなかった. 腹部血管造影検査でS5に腫瘍濃染像がみられ, CT-APにてperfusion defectを呈し肝細胞癌と診断, TAEを施行した. しかし, 壊死効果不十分であったため, 開腹下にマイクロ波凝固療法およびリンパ節摘出術を行った. 肝腫瘍は生検にて低分化型肝細胞癌と診断され, 摘出したリンパ節に類上皮細胞肉芽腫と転移巣が混在して認められた. 術後約2年健存中である. 悪性腫瘍の数%にサルコイド反応がみられ本邦では胃癌, 肺癌に多いとされているが, 肝細胞癌に伴った報告は自験例を含め5例とまれであり文献的考察を加えて報告する.