Verhandlungen der Deutschen Gesellschaft fur Pathologie最新文献

Gastrointestinal stromal tumors (GISTs), the most common mesenchymal tumors in the gastrointestinal tract, metastasize in up to 50 % of cases and are resistant to conventional radio- and chemotherapy. They are characterized by the expression of the type III receptor tyrosine kinase KIT which is the most important diagnostic immunohistochemical feature. Genomically, the majority of GISTs carry heterozygous mutations in the KIT or the PDGF receptor alpha gene leading to an autophosphorylation of the respective receptor protein. The evaluation of the mutational status allows the subdivision of GISTs into different prognostic sub-groups. For example, GISTs carrying an activating mutation in PDGF receptor alpha are most often located in the stomach and seem to have a better prognosis than GISTs with a KIT mutation. Specific mutational subtypes of KIT mutations in exon 11 (esp. proximal deletions of codons tryptophane-557 and lysine-558) have a significantly higher metastatic risk than GISTs with KIT mutations located in the distal part of exon 11 (esp. insertions/duplications). GISTs in the small bowel most often carry KIT exon 9 mutations and have a worse prognosis than GISTs with exon 11 mutations. Mutational subtype in KIT or PDGF receptor alpha not only influences the biological behavior of GISTs but also their response to treatment with imatinib, a tyrosine kinase inhibitor also inhibiting ARG, PDGF receptor beta and BCR-ABL. KIT exon 11 mutated tumors show response rates of up to 80 % of cases whereas KIT exon 9 mutated GISTs respond in less then 50 %. GISTs without detectable KIT mutation in these both exons often are resistant to imatinib. The development of secondary resistance to imatinib in GIST patients occurs in up to 40% of cases and is partly due to secondary KIT mutations occuring additionally to the primary mutation. Actually, several studies evaluate the efficacy of alternative small molecules such as SU 11248, RAD001 and AMG706 inhibiting signal transduction pathways downstream of KIT and PDGF receptor alpha. In summary, mutational status in KIT or PDGF receptor alpha of GISTs is relevant for prognosis, for response to treatment and for further insights into mechanisms of treatment failure.

The WHO has published an updated classification of mastocytosis and the criteria for the diagnosis of systemic mastocytosis (SM). These include one major criterion, compact mast cell (MC) infiltrates in extracutaneous tissues, and four minor criteria, i.e. cytomorphologic atypia with spindling of MC (>25 %), detection of the activating somatic c-kit mutation D816 V in MC, aberrant expression of CD2 and/or CD25 on MC, and an elevated serum tryptase level (>20 ng/ml). Systemic mastocytosis is diagnosed when the major plus one minor, or three minor criteria are fulfilled. In the present study, we have established methods for the detection of CD25 and the c-kit mutation D816V in paraffin-embedded bone marrow trephine biopsy specimen of 57 patients with various subtypes of mastocytoses and 239 controls. While MCs in almost all patients with SM (55/57) expressed CD25, only 2/239 of the control samples contained CD25-positive MCs. With newly designed molecular pathological methods, c-kit codon 816 mutations were detected by "peptide nucleic acid" (PNA)-mediated PCR-clamping and/or analysis of microdissected MC in 52/57 cases with SM. All cases with detectable c-kit mutations also contained CD25-positive MC. The c-kit mutation D816 V was also detected in microdissected cells of associated hematologic neoplasias in 6/15 cases. With the methods established for the investigation of paraffine-embedded tissues, the pathologist plays a central role in the diagnosis of SM.

Precise prognostication represents one of the essential but still unsolved challenges in breast cancer pathology. There is a striking discrepancy between the plethora of suggested markers that have proved useful in mono-centre retrospective studies, including molecular expression arrays and the only small number of parameters applied in clinical decision finding. When adjuvant therapy is considered clinicians still rely predominantly on traditional parameters like staging and hormonal receptor status. Another traditional marker which has proven its strength in mono-centre studies but is compromised by subjectivity and limited reproducibility is provided by grading. We have conducted a study on how traditional grading markers can be objectified and adapted to small amounts of tissue which have become custom with the wide-spread use ob needle biopsies. A modified grading scheme replacing mitosis counting by Ki-67 immunohistochemistry and nuclear pleomorphism by digital determination of nuclear size was applied to 346 cases of breast cancer with a median follow-up of 6 years in a tissue micro-array. A highly significant correlation with overall and disease-free survival could be established in this retrospective study although not more than 1.4 square millimeters of tissue were evaluated. When combined with nodal status and progesterone receptor evaluation a subgroup free of any relapse could be identified. It is concluded that standardized and objectified application of grading as a traditional tissue-based marker of prognosis can improve its impact considerably even in limited amounts of tissue.

The treatment of patients with breast cancer has progressively become multidisciplinary. Considering that the establishment of standards of care for medical treatment is a process of building consensus by using the best available scientific evidence, multidisciplinary guidelines have been developed in Germany to promote better and more consistent management of breast cancer patients (www.krebsgesellschaft.de). These guidelines provide a framework for clinical decision-making and pathological assessment that gives clinically useful and prognostically significant information. The improvement of standards of care is subject to the definition of procedures at the interface between the different involved disciplines. The following topics at the surgery-pathology interface are critical for the optimal management of breast cancer and should be coordinated, especially with regard to breast conserving therapy: 1. Unequivocal marking of the tissue specimens by the surgeon in order to obtain proper orientation. 2. Intra-operative frozen sectioning. 3. Residual tumour (R) classification (UICC, 2002) and adequate distance to resection margins (for DCIS and invasive carcinomas). 4. Specific requirements on the pathological examination of surgical specimens after primary systemic treatment (neoadjuvant chemotherapy), i. e. the assessment of tumour response and the extent and distribution of tumour residues.

The main reasons for applying a classification system to invasive breast carcinoma are to obtain a correlation with prognosis and tumour biology. Invasive carcinomas may be sub-divided morphologically according to their degree of differentiation. This is achieved in two ways, by assessing histological type and histological grade. A wide range of histological patterns is recognised in invasive carcinoma of the breast and four broad prognostic groups are recognised: the excellent prognosis group comprises tubular, cribriform, mucinous carcinomas; the good group tubular mixed, mixed ductal NST/special type and classical lobular carcinoma; the average group mixed lobular, medullary and atypical medullary carcinoma and the poor group is composed of ductal NST, mixed ductal and solid lobular carcinoma understanding of the biology of breast cancer. For example, tumours with a medullary phenotype which express basal cytokeratins and are p53 positive and ER and c-erbB-2 negative are strongly predictive of the BRCA-1 gene-mutation carrier state. Histological grading refers to the semi-quantitative evaluation of the morphological structure of breast carcinomas. In the Nottingham method three characteristics of the tumour are evaluated, glandular differentiation, nuclear pleomorphism and mitotic counts. A numerical scoring system on a scale of 1-3 is used to ensure that each factor is assessed individually. Overall grade is assigned as follows: Grade 1: 3-5 points, Grade 2: 6-7 points, Grade 3: 8-9 points. There is a highly significant relationship between histological grade and prognosis; survival worsens with increasing grade. Histological grading has been shown to have good reproducibility and has been adopted for use in Europe, Australasia and the United States. When combined with pathological tumour size and lymph node stage into the Nottingham Prognostic Index there is excellent stratification for patient management.

Primary mediastinal B-cell lymphoma (PMBL) is a well-defined subtype of diffuse large B-cell lymphoma. Molecular cytogenetics revealed frequent gains of 9 p24. JAK2, mapping in this region, is presently regarded as a candidate oncogene since expression profiling showed high JAK2 transcript levels and JAK2 was found to be constitutively phosphorylated in mediastinal B-cell lymphomas. We confirm that in the MedB-1 mediastinal B-cell line, harbouring a trisomy 9, JAK2 transcription is elevated and the product is highly phosphorylated. However, JAK2 is not over-expressed at the protein level. On top, JAK2 protein turnover is even delayed. This unexpected finding coincides with a biallelic mutation of the SOCS-1 gene in this cell, which abrogates SOCS box function of the protein. Ectopic expression of wt-SOCS-1 in MedB-1 leads to growth arrest, dramatic reduction of phospho-JAK2 and its downstream partner phospho-STAT5. We conclude that, in MedB-1, action of phospho-JAK2 is sustained due to defective SOCS-1. Hence, SOCS-1 qualifies as a novel tumor suppressor. Of note, the SOCS-1 mutations are also present in the parental tumor of MedB-1 and were detected in 9 of 20 PMBL.

Several studies have examined the expression profiles of human hepatocellular carcinomas (HCCs) using high density microarray technology, but subtyping with potential mechanistic and therapeutic impact has not been achieved so far. Here we have analysed the expression pattern of human HCCs and HCC cell lines in comparison to normal liver. A characteristic of one group of HCCs and all HCC cell lines was overexpression of insulin-like growth factor (IGF)-II. Moreover, IGF-II expression was mutually exclusive to induction of several IFN-related genes. In vitro, treatment of HCC cells with IFNgamma leads to a strong reduction of IGF-II expression. Equally, specific reduction of IGF-II was achieved using RNAinterference in HCC cells. Therefore, IGF-II may represent an excellent target for IFNgamma-treatment and specific siRNA-mediated therapeutic intervention.

The new WHO series on Pathology and Genetics of Tumours of the Breast and Female Genital Organs (33) defined to name the group of epithelial ovarian tumors with a dignity between benign and malignant exclusively as Borderline Tumors of the Ovary (BOT) and to skip the term "... of low malignant potential". Further, the term "atypical proliferative tumour" was not recommended by the WHO. During a Consensus Meeting on Borderline Tumors of the Ovary held at Bethesda on August 27-28, 2003 (2) the expert panel also recommended to use the BOT terminology. However the term "tumour of low malignant potential" and--less favourable--"atypical proliferative tumour" may be used as synonym. Both groups agreed unanimously that the name carcinoma should not be included in the diagnosis. The group of borderline ovarian tumors is heterogeneous. 80 to 90% of the cases have a very favourable prognosis while 10-20% exhibit a recurrent clinical course with peritoneal implants and very rarely death from the tumor within 10 years. The morphological criteria and supporting methods for recognizing unfavorable BOT and for distinguishing them from highly differentiated ovarian carcinomas are summarized. The prognostic importance of peritoneal implants is described. The concept of micropapillary serous carcinomas (MPSC) and its implications on the diagnostic work of pathologists will be discussed. The presented data focus on serous tumors since this is by far the most common variant.

Deregulated expression of Matrix Metalloproteinases (MMPs) and Tissue Inhibitors of Metalloproteinases (TIMPs) is an important pre-requisite for metastatic processes in a variety of human tumor types including renal cell cancer. Own previous cDNA microarray studies demonstrated differential expression of several MMPs and TIMPs in normal renal tissue and renal cancer cell lines. In order to analyze MMP/TIMP expression in primary clear-cell renal cell carcinoma (ccRCC) tissues we have determined the mRNA abundance of MMP-2, MMP-9, TIMP-1 and TIMP-2 by RT-PCR in 29 ccRCC and 7 normal renal tissues. Compared to normal renal tissue, expression of MMP-2 and TIMP-2 was significantly reduced in 16 and 12 of 29 ccRCCs, respectively. In contrast, MMP-9 expression was significantly increased in 11 of 29 ccRCCs. No difference was seen for TIMP-1 transcription levels. Because expression of the metastasis-associated CXCR4 chemokine receptor is increased and associated with poor tumour-specific survival in ccRCC we also compared MMP/TIMP and CXCR4 expression in the given tissue samples. Expression of TIMP-1 and TIMP-2 did not correlate with CXCR4 expression levels, whereas mRNA expression of MMP-2 and MMP-9 was significantly higher in tumours with strong CXCR4 expression (p = 0.04 and p = 0.01, respectively). These preliminary results suggest the involvement of CXCR4, MMP-2, and MMP-9 in renal cancer progression.

All the preliminary observations on a lot of marker sets defining different stages in the tumor development are building a framework of work hypothesis which can be verified in characterising large pools of histological uniform rated paraffin probes. We developed a bootstrapping algorithm based on correlation measures to uncover regulatory patterns of immunohistochemical characterized tissue arrays with 550 invasive breast cancer cases. The algorithm is implemented in 'S' a computer language used to model mathematical solutions. Focussing on the Cytokeratins versus a set of prominent markers in breast cancer differentiation it will be obvious that markers which are known to appear in early (progenitor) forms conform to CK5/6 and CK14 while others associated with late stages conform to CK8/18 and CK19. Markers examined are among others EGFR, EMA, erb-B2, Vimentin, p53, ER and PR. The developed approach is an elegant and complete procedure to reveal the real regulatory patterns which are enclosed in a certain experimental design. The statistical significance of the results calculated by our algorithm is generally high and in the presented experimental design smaller than 0.6 * 10E-6.