[Lynch syndrome in the hands of pathologists]. / Lynchuv syndrom v rukách patologa.

Lynch syndrome (formerly hereditary non-polyposis colorectal cancer) is the most common familial colorectal cancer syndrome with a known molecular genetic background. The syndrome is caused by a germline mutation of one of the genes encoding mismatch repair (MMR) proteins that are responsible for DNA replication errors repair. Impaired function of these proteins leads to microsatellite instability (MSI) and forms a suitable background for the development and progression of tumors, mainly colorectal cancer. Traditionally, Lynch syndrome was regarded to be responsible for 2 % of all cases of colorectal cancer, however recent estimates reach even 5 %. Due to this relatively high frequency, familial occurence, the absence of the premorbid phenotype and the development of malignant tumors during the productive years of life, the correct diagnosis becomes not only a medical, but also a socioeconomical problem. Unfortunately, clinical means of diagnostics of Lynch syndrome (like the Amsterdam criteria and Bethesda guidelines) lack sensitivity. It was shown that predictive models based on histological signs of MSI are more sensitive than the clinical criteria used to detect patients suspicious of Lynch syndrome. Of all MSI-H colorectal cancers, 1/5 is caused by Lynch syndrome, the rest being only sporadic cancers caused by epigenetic inactivation of a MMR protein. To rule out the sporadic cases, molecular genetic investigation of the BRAF gene and methylation analysis of MLH1 is used in the diagnostic workup of Lynch syndrome. The suspicion of Lynch syndrome, based on the results of the assortment of diagnostic methods mentioned above, should be proven by detection of a germline mutation of an MMR gene in peripheral blood, and followed by screening of family members, which is a necessary condition for efficient prevention.

Mutational analysis of driver genes defines the colorectal adenoma: in situ carcinoma transition.

A large proportion of colorectal carcinomas (CRC) evolve from colorectal adenomas. However, not all individuals with colonic adenomas have a risk of CRC substantially higher than those of the general population. The aim of the study was to determine the differences or similarities of mutation profile among low- and high-grade adenomas and in situ carcinoma with detailed follow up. We have investigated the mutation spectrum of well-known genes involved in CRC (such as APC, BRAF, EGFR, NRAS, KRAS, PIK3CA, POLE, POLD1, SMAD4, PTEN, and TP53) in a large, well-defined series of 96 adenomas and in situ carcinomas using a high-throughput genotyping technique. Besides, the microsatellite instability and APC and MLH1 promoter methylation were studied as well. We observed a high frequency of pathogenic variants in the studied genes. The APC, KRAS and TP53 mutation frequencies were slightly lower in adenoma samples than in in situ carcinoma samples. Further, when we stratified mutation frequency based on the grade, the frequency distribution was as follows: low-grade adenoma-high-grade adenomas-in situ carcinoma: APC gene 42.9-56.0-54.5%; KRAS gene 32.7-32.0-45.5%; TP53 gene 8.2-20.0-18.2%. The occurrence of KRAS mutation was associated with the presence of villous histology and methylation of the APC promoter was significantly associated with the presence of POLE genetic variations. However, no association was noticed with the presence of any singular mutation and occurrence of subsequent adenoma or CRC. Our data supports the multistep model of gradual accumulation of mutations, especially in the driver genes, such as APC, TP53 and KRAS.

Detection of galectin-3 in patients with inflammatory bowel diseases: new serum marker of active forms of IBD?

OBJECTIVE: It is an open question whether multifunctional galectin-3 can be a serum marker in inflammatory bowel disease. METHODS: Western blots and commercial ELISA detected and quantitated the lectin immunocytochemistry using double labeling localized it in tissue sections. RESULTS: Serum concentrations were significantly increased in specimen of patients with active and remission-stage ulcerative colitis and Crohn's disease, associated with emerging positivity of CD14(+) cells. CONCLUSION: Enhanced concentration of galectin-3 in serum reflects presence of disease and points to its involvement in the pathogenesis.

[Crohn's disease and infectious agents]. / Crohnova nemoc a infekcni agens.

The author discusses possible etiological causes of Crohn's disease taking into consideration the undoubtedly significant impact of the constitution of the intestinal microbial flora. The author pays special attention to Yersinia; their presence in the intestines is believed to be the chief mechanism of subsequent immunity events resulting in the development of the disease. The author briefly discusses the possibilities of differential diagnosis and of treatment. He mentions the profitable cooperation of infectiousdiseases specialists and gastroenterologists in the diagnosis of diarrhoeal disorders.

Reactive nodular fibrous pseudotumors of the gastrointestinal tract: report of 8 cases.

Eight cases of reactive nodular fibrous pseudotumor of the gastrointestinal tract are presented. The patients included 6 males and 2 females between the ages of 1 and 68 years (mean age 41.5 years). Three tumors involved the small intestine, and 5 of the investigated lesions were located in the large bowel. Of these, 2 originated in the sigmoid colon, 1 in the cecum, 1 in the appendix, and 1 in the large bowel not otherwise specified. The tumors' size varied from 3 to 10 cm in the greatest diameter (mean 6.2 cm). Histologically they were composed of stellate or spindle shaped cells resembling fibroblasts arranged haphazardly or in intersecting fascicles, embedded in a collagen-rich stroma, with sparse intralesional mononuclear cells frequently arranged in lymphoid aggregates. Immunohistochemically, the lesions were positive for vimentin (7/7), smooth muscle actin (8/8), muscle-specific actin (5/7), cytokeratins AE1/AE3 (6/7), and CAM 5.2 (1/7), and antigen CD68 (1/7). No case (0/8) reacted positively with antibody to CD117 (c-kit). Genetically no substitutions, deletions, or insertions occurred in exon 11 in all analyzed samples. Likewise, no deletions or insertions in part of exon 9 were observed. Ultrastructurally the tumor cells revealed features typical of myofibroblasts. According to the morphologic, immunohistochemical, and ultrastructural features mentioned above, especially to the positivity of low-molecular-weight cytokeratins, we propose this lesion to be related to a proliferation of multipotential subserosal cells rather than ordinary myofibroblasts or fibroblasts.

Improvements in colorectal cancer screening programmes - quantitative immunochemical faecal occult blood testing - how to set the cut-off for a particular population.

OBJECTIVE: The aim of the study was to determine the optimum cut-off value of the quantitative immunochemical test (q-FIT) OC-Sensor for colorectal cancer and advanced adenomatous polyps in a particular population. METHODS: 815 patients were referred for colonoscopy and were offered two q-FIT examinations at two different colonoscopy centers. The patients were classified according to the colonoscopic findings. Test sensitivity, specificity, and accuracy were statistically evaluated using one test and two tests at the levels of 50, 75, 100, 125, and 150 ng/mL of faecal hemoglobin in those patients with advanced polyps and colorectal cancer. The optimum cut-off test level for clinically significant neoplasia was determined using one test. RESULTS: The optimum cut-off value of q-FIT OC-Sensor for the detection of clinically significant neoplasia in our particular population was determined as 75 ng/mL using one test. This value provides an optimum proportion of 73% sensitivity (±95% CI 60.3% - 83.4%) and 90% specificity (±95% CI 86.8% - 92.8%), PPV and NPV were determined as 54.76% and 95.43% respectively. CONCLUSIONS: The first step in the implementation of q-FIT test in the screening program in our country is to determine the optimum cut-off level for a population, and to estimate the number of tests performed with respect to the optimum cost effectiveness and economical climate. Using one test, the optimum level of q-FIT OC-Sensor® in the Czech Republic was determined as 75 ng/mL. This study could serve as a model for further studies in other countries, where screening does not yet exist.

Comparison of morphological, immunohistochemical, and molecular genetic features of inflammatory fibroid polyps (Vanek's tumors).

Vanek's tumor (inflammatory fibroid polyp) is a rare benign lesion occurring throughout the digestive tract. Histologically, two patterns can be recognized. Classical Vanek's tumor contains concentric formations of proliferating spindle cells which are CD34 positive. Atypical, inflammatory pseudotumor-like Vanek's tumor lacks concentric formations and is CD34 negative. Recently, mutations in platelet-derived growth factor receptor alpha (PDGFRA) were reported in gastric and small intestinal Vanek's tumors. In this study, KIT exons 9, 11, 13, and 17, PDGFRA exons 12, 14, and 18, and a part of exon 15 BRAF for point mutation V600E were screened in 23 cases of Vanek's tumor, both classical (n = 16) and inflammatory pseudotumor-like (n = 7). No mutations in all analyzed exons of KIT and BRAF and in exon 14 of PDGFRA were detected. Six Vanek's tumors harbored activating mutations in PDGFRA exons 12 (n = 5) and 18 (n = 1) respectively: S566_E571delinsK (n = 1), S566_E571delinsR (n = 4), and D842 del (n = 1). The mutations were detected in the classical (n = 5), as well as inflammatory pseudotumor-like (n = 1) Vanek's tumors. The results of this study suggest that the two morphological patterns of Vanek's tumor more probably represent only variants of one type of tumor than two different lesions. Furthermore, BRAF mutations were not shown to drive growth of PDGFRA wild-type Vanek's tumors.

Optical biopsy system distinguishing between hyperplastic and adenomatous polyps in the colon during colonoscopy.

BACKGROUND: It has been established that the removal of adenomatous colon polyps drastically reduces the incidence of colorectal cancer (CRC), but polypectomy is not without risk. The aim was to determine the correlation between the results of an optical biopsy system and the histopathology report of the physical biopsy specimens of the same polyps removed at colonoscopy. PATIENTS AND METHODS: Paired optical and physical biopsies were performed on 55 polyps with complete polypectomy of the same tissue. RESULTS: Fifty-three adenomatous polyps and two hyperplastic polyps were identified by the hospital pathologist. The optical biopsy system identified 52 polyps as suspect (adenomatous) and 2 as non-suspect (hyperplastic). One villous adenoma could not be optically analyzed due to friability. CONCLUSION: The WavSTAT Optical Biopsy System provides accurate information to the gastroenterologist to assist in distinguishing between hyperplastic and adenomatous polyps. It is safe for the patient and does not unduly increase the time required for an endoscopic examination.

Progress in molecular diagnostics of gastrointestinal stromal tumors.

Gastrointestinal stromal tumor (GIST) is the most frequent mesenchymal tumor of the alimentary tract, presently being defined as a tumor composed of spindle and/or epithelioid cells presumably differentiating towards interstitial cells of Cajal. The most frequent location of gastrointestinal stromal tumor is the stomach, followed by other sites of gastrointestinal tract. Occasional sites of occurrence are mesenterium, omentum, retroperitoneum, gall bladder, urinary bladder, pancreas, prostate and the vagina. Most of these tumors are KIT-immunoreactive and almost all carry mutated KIT or PDGFRA genes encoding two transmembrane class III tyrosine kinases. These mutations not only shed light on molecular oncogenesis of GISTs, but can also serve as diagnostic markers of this type of tumor, and, last but not least, the function of the proteins encoded by the mutated genes may be influenced by small molecule tyrosine kinase inhibitors. Nevertheless, negative results of immunohistochemistry and mutational analysis do not exclude histologically proven diagnosis of GIST, and although the response to tyrosine kinase inhibitors is correlated with the presence and type of KIT and PDGFRA mutations, the molecular genetic analysis of these genes is presently not required for imatinib therapy of GISTs.

Pigmented solid-pseudopapillary neoplasm of the pancreas.

A hitherto unrecognized variant of solid-pseudopapillary neoplasm of the pancreas is reported. The tumor presented in the pancreatic head of a 57-year-old female patient. It was a well-circumscribed, encapsulated nodule measuring 27 mm in diameter, with variegated yellow to brown and gray cut surface. Histologically, the neoplasm was composed of uniform polyhedral cells arranged around delicate fibrovascular cores retaining their solid pattern in the periphery, whereas central parts of the tumor were characterized by the formation of papillae and smaller pseudocysts. Neither mitotic activity nor invasive growth were found. Immunohistochemically, tumor cells were positive for vimentin, neuron-specific enolase, and CD56, whereas they were negative in reactions with antibodies directed against other neuroendocrine markers, cytokeratins, melanocytic markers, and pancreatic amylase. In addition to these typical findings, intracellular pigmented granules were found in the darker brown zones of the tumor. They were positively stained in periodic acid-Schiff reaction after diastase digestion, sudan black B, and in Schmorl stain. In contrast, they were not stained with Fontana-Masson, Ziehl-Neelsen, and Perls stains. Ultrastructurally, the pigment consisted of dense granules with lipid droplets resembling modified lysosomes. These results exclude the possibility of a melanogenic nature of the pigment and instead determine it as lipofuscin.

Epitopes of calreticulin recognised by IgA autoantibodies from patients with hepatic and coeliac disease.

Calreticulin (CRT) was identified as a frequent target of serum autoantibodies (Ab) in various diseases, but anti-CRT Ab of IgA isotype were described only in coeliac (CLD) and some hepatic diseases. Employing ELISA with recombinant CRT we found significantly higher (P<0.001) levels of IgA anti-CRT Ab in sera of patients with primary biliary cirrhosis (PBC) (77.6+/-8.9 AU/mean+/-SE), autoimmune hepatitis (AIH) (105.1+/-9.2 AU) and alcoholic liver cirrhosis (ALC) (193.5+/-21.0 AU) relative to healthy controls (38.6+/-2.0 AU). The levels of IgG anti-CRT Ab in sera of patients with PBC (59.5+/-3.4 AU), AIH (89.7+/-7.9 AU) and ALC (86.4+/-6.2 AU) were also significantly increased (P<0.001) when compared with controls (38.5+/-2.1 AU). Pepscan technique with decapeptides of CRT (each overlapping by eight amino acids) revealed antigenic epitopes of this molecule recognised by IgA Ab of almost all tested patients-KGKNVLINKD and QVKSGTIFDNFL. We also identified disease specific antigenic epitopes on CRT molecule, predominantly recognised by IgA Ab of patients suffering from a particular disease: GGYVKLFPNS and YVKLFPNSLD in AIH (83%, 92% of patients), GLQTSQDARF and EQRLKEEEED in CLD (both 75%) and ASKPEDWDER in ALC (67%). Identification of disease specific CRT epitopes contributes to clarification of autoreactivity against this molecule.

Vanek's tumor (inflammatory fibroid polyp). Report of 18 cases and comparison with three cases of original Vanek's series.

Eighteen cases of Vanek's tumors are presented. The patients included nine men and nine women between the ages of 45 and 93 years (mean, 66.2 years). Nine cases were clinically diagnosed as polyps of the gastric antrum, five cases as polyps of the stomach (not otherwise specified), one polyp was located in the ileum and the three remaining polyps in the small intestine (not otherwise specified). The thirteen polyps with available size information measured from 0.4 to 5 cm in the greatest diameter (mean, 2.2 cm). Immunohistochemically, the affections were positive for vimentin (18/18) and CD34 (15/18). All the cases negative for CD34 also lacked concentric onion skin-like formations of the spindle cells around glands and vessels. The different immunophenotype and absence of concentric formations could be explained by the existence of two different lesions commonly designated as Vanek's tumor (inflammatory fibroid polyp) or by the hypothesis of various evolutional stages. In the differential diagnosis, it is important to distinguish namely eosinophilic gastroenteritis, gastrointestinal stromal tumor, inflammatory pseudotumor, hemangioendothelioma, and hemangiopericytoma. In contrast to gastrointestinal stromal tumors, genetically no substitution, deletion, or insertion occurred in c-kit exon 11 in all analyzed samples. Likewise, no deletion or insertion in part of c-kit exon 9 was observed.