The malignant potential of colorectal adenomas highly correlates with their pathological characteristics, such as size, histology and grade of dysplasia. Currently, based on these parameters, adenomas are characterized as "non-advanced or advanced" and patient surveillance is adjusted accordingly. The aim of this study was to investigate the correlation between the KRAS mutations and characteristics of non-advanced and advanced colorectal adenomas for predicting the risk of increased malignant potential of adenomas that may influence the decision to offer follow-up endoscopic surveillance. We used a mutagenic polymerase chain reaction - restriction fragment length polymorphism method to determine KRAS mutations in 164 colorectal sporadic polypoid adenomas (51 non-advanced-, 113 advanced adenomas) and in 40 early colorectal carcinomas. The method of mutation detection was validated according to recommendation for KRAS mutation testing in colorectal carcinoma of the European Quality Assurance Program. The limit of detection of the assay was 3 % mutated DNA with a good reproducibility. Evaluation of pathological characteristics was performed according to European Guidelines for Quality Assurance in Colorectal Cancer Screening and Diagnosis. The morphological parameters of the adenoma such as size, histology, grade of dysplasia are highly correlated with one another: an increasing adenoma size raised the proportion of villous histology and degree of dysplasia (all p < 0.0001). KRAS mutations were detected in 31 % of the non-advanced adenomas, in 57.5 % of the advanced adenomas and in 62.5 % of the early carcinomas. Most mutations occurred at codon 12 rather than at codon 13 (72 %, 82 %, 76 % versus 22 %, 17 %, 24 %, respectively). There was no significant difference in association of KRAS mutation with age, gender, location among non-advanced-, and advanced adenomas and early carcinomas. KRAS mutation was found more often in tubulovillous and villous adenomas, whereas wild-type KRAS was observed more frequently in tubular adenomas (P < 0.0001) and there was an increased prevalence of KRAS mutations in larger adenomas (P < 0.0001). In this study KRAS mutation occurred with the same frequency in adenomas with low-grade (48 %) and high-grade (50 %) dysplasia. KRAS mutation is very strongly associated with a villous architecture and through villous component expansion, KRAS mutations may increase risk of tumor progression in sporadic colorectal polypoid adenomas.

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Among the 300 peripheral T-cell lymphomas (PTCL) searched for EBV positive non-resting B-cells by EBER in situ hybridization 12 have been identified with various forms of EBV-driven B-cell proliferation. This could be categorized into three major forms. i. In the first form scattered immature, mononuclear B-cells of immuno-, centroblastic type with CD20+. CD30+ CD45+, LMP1+ phenotype, reactive appearance and polyclonal immunoglobulin heavy chains gene rearrangement (IgH-R) were admixed to the PTCL cells. ii. The second form mimicked diffuse large B-cell lymphoma as homogenous sheets, largely demarcated from the PTCL, of mononuclear, immature B-cell of CD20+, CD30+, CD45+, LMP1+, EBNA-2+ phenotype but with lack of monoclonal IgH-R were present. iii. In the third form scattered Hodgkin-Reed-Sternberg (HRS) type of cells were noticed which exhibited the CD15+/-, CD20-/+, CD30+, CD45-, LMP1+, EBNA-2- phenotype and in 50% showed clonal IgH gene rearrangement in whole tissue DNA extract. The IgH associated transcription factors' (OCT2, BOB.1/OBF.1, PU.1) expression patterns in these cells corresponded to those of HRS cells in cHL. Based on analysis of 65 PTCLs, we have identified in the positive cases a highly significant increase of EBV+ small, reactive, resting B-cell compartment (75.9 / 100 HPF in PTCL vs. 1.5 / 100 HPF in control lymph nodes) likely to be due to the decreased immune surveillance. This progressive accumulation of EBV+ by-stander B-cell population in PTCLs might be the source of various B-cell proliferations, which in any form represent major diagnostic pitfalls and require a careful differential diagnostic procedure.

A total of 106 trephine biopsy specimens with clinical, laboratory and pathology findings corresponding to chronic myeloproliferative disorders (CMPD) were analyzed to reveal the nature of the lymphoid infiltrate in the bone marrow. Histological investigation in 31 chronic myeloid leukemia (CML), 29 CMPDs not otherwise specified (CMPD-NOS), 28 essential thrombocytosis (ET), 15 polycythemia vera (PV) and three chronic eosinophilic leukemia/hypereosinophilic syndrome (CEL/HES) exhibited in 32% various amounts of lymphocytic infiltrate of sparsely to moderately diffuse or nodular types in the bone marrow, but the reactive or coinciding lymphomatous nature could not be revealed by histology alone in the majority of cases. PCR analysis of the immunoglobulin heavy chain (IgH) gene rearrangement was successfully performed in 81 out of the 106 DNA specimens extracted from formol-paraffin blocks. Out of the 81 samples with good-quality DNA, 18 gave a single or double discrete amplification band(s), which was reproducible only in four specimens. Sequencing finally proved monoclonal B-cell population of both pre-and postfollicular origin in all four samples (5%), one CML and three CMPD-NOS. Detailed clinical and pathological investigations indicated overt B-cell malignant lymphoma with clonal relationship to the CMPD in two out of these four patients. We conclude that detailed molecular analysis of IgH gene rearrangement in bone marrow samples of CMPD patients is needed to identify the true monoclonal B-cell infiltration, which-even without overt malignant lymphoma-may occur in this group of disorders.

1. Brissett AE, Olsen KD, Kasperbauer JL et al. Merkel cell carcinoma of the head and neck: a retrospective case series. Head Neck 2002; 24; 982-988. 2. Moll I, Zieger W, Schmelz M. Proliferative Merkel cells were not detected in human skin. Arch. Dermatol. Res. 1996; 288; 184-187. 3. Llombart B, Monteagudo C, Lopez-Guerrero JA et al. Clinicopathological and immunohistochemical analysis of 20 cases of Merkel cell carcinoma in search of prognostic markers. Histopathology 2005; 46; 622-634. 4. Fernandez-Figueras MT, Puig L, Musulen E et al. Prognostic significance of p27Kip1, 45Skp2 and Ki67 expression profiles in Merkel cell carcinoma, extracutaneous small cell carcinoma, and cutaneous squamous cell carcinoma. Histopathology 2005; 46; 614-621. 5. Parrado C, Bjornhagen V, Eusebi V et al. Prognosticating tools in primary neuroendocrine (Merkel-cell) carcinomas of the skin: histopathological subdivision, DNA cytometry, cell proliferation analyses (Ki-67-immunoreactivity) and NCAM immunohistochemistry. A clinicopathological study in 25 patients. Pathol. Res. Pract. 1998; 194; 11-23. 6. Erickson LA, Papotti M, Volante M, Jin L, Lewis JE, Lloyd RV. Merkel cell carcinomas: expression of S-phase kinase-associated protein 2 (Skp2), p27, and proliferation markers. Endocr. Pathol. 2003; 14; 221-229. 7. Carson HJ, Reddy V, Taxy JB. Proliferation markers and prognosis in Merkel cell carcinoma. J. Cutan. Pathol. 1998; 25; 16-19. 8. Fernandez-Figueras MT, Puig L, Musulen E et al. Prognostic significance of p27, p45 and Ki67 expression profiles in Merkel cell carcinoma, extracutaneous small cell carcinoma, and cutaneous squamous cell carcinoma. Histopathology 2005; 46; 614-621.