No abstract

α-Methylacyl-CoA-racemase (AMACR) is an essential enzyme in the oxidation of bile acid intermediates and branched-chain fatty acids. This study aims to examine the expression pattern, as well as diagnostic and prognostic significance, of AMACR in carcinoma, dysplasia and non-neoplastic epithelium of the stomach. A total of 158 cases, including 66 cases of gastric carcinoma (GC), 48 cases of dysplasia and 44 cases of non-neoplastic gastric mucosa, were examined by immunohistochemistry for AMACR. AMACR expression was divided into two categories: negative (negative-weak staining intensity) and positive (moderate-strong staining intensity). AMACR immunoreactivity was detected in only 2 of 44 (4.5%) cases of non-neoplastic epithelium. A significantly high frequency of AMACR expression was found in 40 of 48 (83.3%) cases of dysplasia and 34 of 66 (51.5%) carcinoma cases compared with cases of non-neoplastic epithelium (p < 0.05). The frequency of AMACR expression was significantly higher in dysplasia than in carcinoma cases (p < 0.05). AMACR expression was higher in intestinal- than diffuse-type GC (p < 0.05). In conclusion, this study suggests that AMACR immunostaining aids in distinguishing malignant or precancerous lesions from reactive epithelial atypia in gastric biopsy specimens. It also suggests that AMACR expression is more likely to be associated with intestinal-type adenocarcinoma in gastric carcinogenesis.

Microsatellite instability (MSI) due to defective DNA mismatch repair (MMR) is a form of genomic instability underlying the tumorigenesis of various human neoplasms. To evaluate the roles of MSI in the pathogenesis of gastric carcinomas with squamous differentiation, 17 primary stomach cancer patients (15 adenosquamous and two squamous cell carcinomas) were examined for MSI frequency using five microsatellite markers and the criteria for MSI recommended by the National Cancer Institute Workshop. The molecular causes and consequences of MSI in these neoplasms were further researched through the immunohistochemistry of MMR proteins and the mutational analysis of cancer-associated genes targeted by MSI, respectively. Two of the 17 (12%) cases demonstrated MSI at the most examined loci and were classified as having high level MSI (MSI-H). These tumors also exhibited frame-shift mutations at mononucleotide repeats in the target genes, including TGFbetaRII, IGFIIR, BAX, and hMSH6. It is interesting to note that the mutations of the serine (AGC)13 repeats within the E2F-4 gene were found only in the squamous cell carcinoma portions of them, whereas such alterations were not detected in any of the adenocarcinomatous portions. This suggests that E2F-4 might be implicated in the transformation of adenocarcinoma into squamous cell carcinoma and further studies are needed to understand its role in squamous differentiation.

Neuroendocrine tumors (NETs) can arise throughout the body. Most NETs in the liver are metastatic tumors; primary hepatic NET (PHNET) is extremely rare. A diagnosis of PHNET is very difficult. No single modality can diagnose PHNET by itself, and it often resembles other hypervascular masses of the liver. This paper reports the case of a 51-year old female with a large hepatic mass. Unlike most of PHNETs reported previously, it was composed of a solid mass with mainly multiple cystic lesions, which led to an erroneous diagnosis of hepatic mucinous cystadenoma or cystadenocarcinoma. PHNET with cystic lesions is extremely rare, and the features are not well studied. This case may help physicians suspect PHNET in a differential diagnosis of an atypical hepatic mass.

We report a case of colonic metastasis from ovarian cancer presented as an intraluminal fungating mass mimicking primary colon cancer 8 years after surgery for ovarian cancer. A 70-year-old woman presented with constipation. She had undergone an extended total abdominal hysterectomy with bilateral salpingo-oophorectomy for an ovarian papillary serous cystadenocarcinoma 8 years earlier. Colonoscopy showed a large fungating mass 10 cm from the anal verge that was suspected to be colorectal cancer. A computed tomography scan showed a bulky intraluminal fungating mass in the rectosigmoid junction. After a lower anterior resection and a pathologic diagnosis, a diagnosis of a papillary serous adenocarcinoma due to metastasis from an ovarian tumor was made for this patient.