Paclitaxel-coated stents to prevent hyperplastic proliferation of ureteral tissue: from in vitro to in vivo.

Ureteric stents have become an indispensable tool in the armamentarium of every urologist. However, they carry their own morbidity resulting mostly from infectious or abacterial fouling and biofilm formation, and/or urothelial hyperplastic reaction. All of these may interact and lead to clinical complications. Many different stent designs and coatings have been proposed. In this study, we focused on the effect of paclitaxel-coated stents on hyperplastic proliferation of ureteral tissue, using as example anastomotic strictures after ureteroureterostomy in a rat model. Human urothelial cells (SV-HUC-1) were used to determine paclitaxel dosages in vitro. Polyurethane stents were coated with a paclitaxel containing biodegradable polymer and studied in a ureteroureterostomy rat model. 48 male 9-week-old Sprague-Dawley rats underwent either sham surgery (n = 16) or ureteroureterostomy with sutured anastomosis, and consecutive stenting with either a paclitaxel-coated or an uncoated stent (16 per group), respectively. The animals received daily intraperitoneal injections of 5-bromo-2-deoxyuridine (20 mg/ml, 100 mg/kg body weight) during the first eight postoperative days, and were sacrificed on day 28. Healing of the ureteral anastomosis and proliferation of urothelial cells was examined histologically and immunohistochemically. In vitro, a concentration of 10 ng/mm2 paclitaxel can be considered as non-toxic, while still exerting an anti-proliferative effect on urothelial cells. Histologically, typical wound healing processes were seen at the site of the ureteral anastomosis in vivo. Proliferation of urothelial cells was significantly lower in animals with paclitaxel-coated stents compared to those with uncoated stents (LI 41.27 vs. 51.58, p < 0.001). Our results indicate that stenting of ureteral anastomoses with paclitaxel-coated stents can reduce hyperplastic proliferation of ureteral tissue. Paclitaxel-coated stents thus might be able to prevent not only scar-induced postoperative stenosis after reconstructive surgery, but also hyperplastic urothelial reaction in non-anastomotic stent patients as part of their inflammatory response to the foreign material.

[Renal cell carcinoma diagnosis and prognosis within the context of the WHO classification 2016]. / Histopathologische Diagnose und Prognose des Nierenzellkarzinoms im Kontext der WHO-Klassifikation 2016.

BACKGROUND: Histological classification of renal cell carcinoma (RCC) has become more and more important for clinical management, but relatively few is known regarding the swiftness with which the 2016 World Health Organization (WHO) classification of RCC was adopted in the daily routine diagnostics. AIM: To retrospectively review the histological diagnosis of RCC within the context of 2016 WHO classification followed by survival analysis. MATERIAL AND METHODS: Retrospective register based analysis of RCC diagnosis between 1998 and 2017 and survival analysis. RESULTS: 1440 RCC cases were registered between 1998 and 1917. According to 2016 WHO classification, 77.7% clear cell RCC and 22.3% non-clear cell RCC were diagnosed. A total of 37 rare subtypes were recorded, among those 1% MiT family translocation RCC, 0.35% acquired cystic disease-associated RCC, 0.35% multilocular cystic renal neoplasm of low malignant potential, 0.35% collecting duct carcinoma, 0.3% mucinous tubular and spindle cell carcinoma, 0.1% clear cell papillary RCC and 0.1% RCC with (angio)leiomyomatous stroma. Cox regression analysis showed significant different overall survival and progression-free survival between the histological subtypes. DISCUSSION: The complexity of the 2016 WHO classification of RCC put high demands on histopathological diagnostics. At University Medicine Center Rostock morphological distinct RCC entities have been mostly diagnosed by conventional means via hematoxillin and eosin stained slides, but beyond immunohistochemistry additionally molecular techniques were established. The histologic subtyping of RCC according to 2016 WHO classification has prognostic significance and might have predictive significance for unique therapeutic approaches.

[Diagnosis of conjunctival neoplastic lesions by confocal in-vivo microscopy]. / Diagnostik konjunktivaler Neoplasien mittels konfokaler In-vivo-Mikroskopie.

BACKGROUND: There is a wide spectrum of benign and malignant conjunctival neoplastic lesions that are often impossible to distinguish clinically by slit-lamp microscopy. The current study was undertaken to compare in-vivo confocal laser scanning microscopy (CLSM) and histology for the preoperative assessment of benign or malignant status. CASE REPORTS: We present the clinical details of three patients. In two cases the neoplastic lesions were classified as benign (actinic keratosis). In-vivo CLSM revealed densely layered, sometimes hyperreflective conjunctival epithelial cells, together with multiple inflammatory cells and microcysts. Correlated findings on histology showed keratinisation with inflammatory infiltrates and intracellular oedema formation. In-vivo CLSM images in the third patient revealed interruptions of the layered epithelial structure with regular conjunctival epithelium co-existing with complexes of enlarged cells with polymorphic nuclei. Histology also showed an abrupt transition from regular squamous epithelium to hyperplastic, dysplastic squamous epithelium. In this case the neoplastic lesion was classified as carcinoma in situ. DISCUSSION: The in-vivo CLSM images correlated positively with histology findings. Although in-vivo CLSM offers the capability to perform non-invasive examinations over time, associated histological assessment (because of its more precise detail and additional staining techniques) remains indispensable for planning further action and determining the prognosis.

[Primary cerebellar T-cell lymphoma]. / Primäres zerebelläres T-Zell-Lymphom.

Primary central nervous system T-cell lymphomas are rare and have to be differentiated from reactive lesions. It is therefore essential to use all possible tools to establish the diagnosis, including immunohistochemistry, molecular genetic analysis, and/or cytogenetic methods. In this paper we present the case of a primary cerebellar T-cell lymphoma in a 50-year-old man; a clonal T-cell receptor gene rearrangement was documented. After two cycles of methotrexate therapy the patient developed Pneumocystis carinii-induced pneumonia, dying 10 weeks after his diagnosis. The autopsy did not reveal any residual tumour.

[The diagnostic and predictive role of kit (CD117)]. / Die diagnostische und prädiktive Bedeutung von Kit (CD117).

KIT (CD117) is a 145-KD transmembrane glycoprotein that is the product of the kit-gene. As a member of the subclass III family of receptor tyrosine kinases, KIT is closely related to the receptors for platelet derived growth factor alpha and beta (PDGF-A and B), macrophage colony stimulating factor (M-CSF), and FLT3 ligand. The ligand for KIT, stem cell factor (SCF), also known as steel factor or mast cell growth factor promotes the dimerisation and autophosphorylation of KIT receptors. The phosphorylated tyrosine residues provide binding sites for signal molecules that contain SH2 domains. KIT mediated signal transduction is critical for the normal development and survival of haematopoietic progenitor cells, mast cells, interstitial cells of Cajal (intestinal pacemaker cells), melanocytes and germ cells. Upon differentiation, KIT expression is lost with the exception of mast cells, melanocytes and interstitial cells of Cajal. The detection of CD117 expression is of paramount diagnostic relevance in gastrointestinal stromal tumors (GIST). About 95% of all GISTs are immunohistochemically CD117 positive. The vast majority of all other sarcoma, carcinoma and also lymphoma are CD117 negative. Therefore, CD117 expression has a high sensitivity and specificity for the diagnosis of GIST. Moreover, activating mutations of KIT tyrosine kinase play a crucial pathogenetic role in GIST 80 to 85% of all GIST's contain activating mutations, primarily in Exon's 11 and 9 of the kit gene. Since the resulting mutant isoformes are sensitive to inhibition by imatinib (glivec), a specific tyrosine kinase inhibitor, the detection of a specific mutation has also a high predictive value. Besides GIST mastocytoses and seminomas are the neoplasias that most commonly express CD117. In contrast to GIST however, these two neoplasias contain mutations in different exons and are only partly imatinib sensitive. Moreover, CD117 expression is by no means entirely specific for these entities. It can also be detected in adenoid cystic carcinomas, thymic carcinomas and melanomas. Very rarely (< 5%) it can also be observed in other carcinomas and sarcomas. However, in the great majority of these cases with a CD117 protein expression there is no corresponding gene mutation of kit. Importantly, the lack of an activating mutation of KIT tyrosine kinase is good evidence that imatinib will not be effective. In other words, detection of sole CD117 protein expression is no solid basis for targeted therapy. The molecular pathological detection of CD117 expression in combination with the corresponding mutational status in patients with GIST (and other tumors) paradigmatically highlights the importance of modern molecular diagnostics in the era of targeted therapy.

Lack of clinical efficacy of imatinib in metastatic melanoma.

This two-centre phase-II trial aimed at investigating the efficacy of imatinib in metastasised melanoma patients in correlation to the tumour expression profile of the imatinib targets c-kit and platelet-derived growth factor receptor (PDGF-R). The primary study end point was objective response according to RECIST, secondary end points were safety, overall and progression-free survival. In all, 18 patients with treatment-refractory advanced melanoma received imatinib 800 mg day(-1). In 16 evaluable patients no objective responses could be observed. The median overall survival was 3.9 months, the median time to progression was 1.9 months. Tumour biopsy specimens were obtained from 12 patients prior to imatinib therapy and analysed for c-kit, PDGF-Ralpha and -Rbeta expression by immunohistochemistry. In four cases, cell lines established from these tumour specimens were tested for the antiproliferative effects of imatinib and for functional mutations of genes encoding the imatinib target molecules. The tumour specimens stained positive for CD117/c-kit in nine out of 12 cases (75%), for PDGF-Ralpha in seven out of 12 cases (58%) and for PDGF-Rbeta in eight out of 12 cases (67%). The melanoma cell lines showed a heterogenous expression of the imatinib target molecules without functional mutations in the corresponding amino-acid sequences. In vitro imatinib treatment of the cell lines showed no antiproliferative effect. In conclusion, this study did not reveal an efficacy of imatinib in advanced metastatic melanoma, regardless of the expression pattern of the imatinib target molecules c-kit and PDGF-R.

Rare expression of KIT (CD117) in lymphomas: a tissue microarray study of 1166 cases.

AIMS: Imatinib mesylate specifically inhibits KIT tyrosine kinase activity, and has been proven to be effective in the treatment of gastrointestinal stromal tumours. Because other KIT-expressing malignancies might benefit from Imatinib therapy, we evaluated the distribution and expression of KIT in 1166 cases of malignant lymphoma. MATERIALS AND RESULTS: Tissue microarrays (TMAs) containing 824 non-Hodgkin's lymphoma (NHL) and 342 Hodgkin's lymphoma (HL) cases were immunohistochemically analysed for the expression of the KIT protein. Two KIT-positive NHLs were sequenced using polymerase chain reaction analysis. One T-cell lymphoma and one follicular lymphoma of the 747 NHL cases (0.3%) were positive for KIT. All HLs were Kit-negative. None of the KIT-positive cases showed a kit gene mutation. CONCLUSIONS: KIT expression is a very rare event in NHL and virtually absent in HL. In the few positive cases, the aberrant expression is not caused by a mutation in the 'hot-spots' of the kit gene, indicating that treatment of these tumours with Imatinib may be ineffective.

Prognostic significance of CD44 expression in diffuse large B cell lymphoma of activated and germinal centre B cell-like types: a tissue microarray analysis of 90 cases.

BACKGROUND: Gene expression profiling of diffuse large B cell lymphoma (DLBCL) revealed three disease types: germinal centre B cell-like (GC), activated B cell-like (ABC), and a "third" type. Expression of CD44 variant isoforms (CD44v) is associated with an unfavourable clinical outcome in DLBCL, but previous studies did not consider the clinicopathological heterogeneity of this disease. AIMS: To analyse the expression and prognostic significance of CD44 in DLBCL types. METHODS: A tissue microarray (TMA) comprising 90 DLBCLs was constructed. CD10, CD20, bcl-2, bcl-6, CD44 standard isoform (CD44s), and CD44v4, CD44v6, and CD44v9 were analysed immunohistochemically and correlated with clinical follow up. RESULTS: TMA expression of CD10, CD20, bcl-2, and bcl-6 showed 100% concordance with results from conventional sections in 60 cases. Samples were segregated into 22 GC (bcl-6+/CD10+/bcl-2-), 25 ABC (bcl-6-/CD10-/bcl-2+), and 35 unclassifiable DLBCLs. Overall survival (OS) at 30 months was 89%, 44%, and 58% in GC, ABC, and unclassified types, respectively. CD44v6 was coexpressed with bcl-2, appeared predominantly on bcl-6 negative cases, and correlated with disease stage. Cases negative for CD44s could be separated into CD44v6 negative (OS, 82% at 70 months) and CD44v6 positive (OS, 58%). CONCLUSIONS: TMA technology is useful for immunophenotyping and clinicopathological analysis of large lymphoma populations. The GC phenotype of DLBCL is of independent prognostic significance for OS. Expression of CD44v6 correlates with disease stage, and might contribute to lymphoma dissemination. CD44v6 is expressed predominantly in ABC DLBCL, and in CD44 negative cases is associated with worse OS.

Mucosal metastases in malignant melanoma.

BACKGROUND: We present the case of a patient with malignant melanoma stage IV according to the American Joint Committee on Cancer (AJCC) classification and an unusual pattern of metastasis to the mucosa of the esophagus, the stomach, the bladder and the palatine tonsil. CASE REPORT: A 38-year-old male patient with metastatic malignant melanoma of stage III (AJCC) was admitted for initiation of adjuvant therapy. 4 months earlier a primary melanoma of the left upper leg had been excised and 2 months later the patient had undergone a left inguinal lymph node dissection revealing 2 metastatic lymph nodes. On admission the patient complained of a sore throat and right cervical lymphadenopathy. He underwent a tonsillectomy and a lymphadenectomy which both revealed melanoma metastases. A PET scan using F-18-fluorodeoxyglucose (FDG) showed focal metabolic activity in the middle mediastinum. Two cycles of dacarbazine (DTIC) chemotherapy were performed during which the patient developed cutaneous metastases, dyspepsia, and mild hematemesis. Gastroscopy revealed bleeding from mucosal metastases of the esophagus and stomach. A few weeks later the patient developed macroscopic hematuria. A cystoscopy was performed and showed metastases to the mucosa of the bladder. Nutrient vessels of these bladder metastases were embolized in order to control bleeding. The patient is currently alive with progressive disease. RESULTS: This case presents common and uncommon sites of metastatic melanoma to the mucosa with the typical clinical manifestations in a single patient.

A differentiation-dependent polyisoprenol kinase in Dictyostelium discoideum.

Crude membrane fractions of Dictyostelium discoideum show the capacity to synthesize (1--3H)dolicholphosphate from (1--3H)dolichol. Formation of dolicholphosphate increased continuously over the first 15 min. The reaction rate was nearly linear with respect to the dolichol content up to 150 microM. The phosphate donor for the reaction is CTP. The optimum concentration of CTP is about 0,75 mM. The reaction is dependent on divalent metal ions, magnesium being more effective than calcium or manganese. The activity of the polyisoprenol kinase depends on the course of the early development. Maximum enzyme activities are present 4--6 h after the induction of the differentiation.