Browsing by Author "Turhan N."

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    A geotraverse across northwestern Turkey: Tectonic units of the Central Sakarya region and their tectonic evolution
    (2000) Göncüoǧlu M.C.; Turhan N.; Şentürk K.; Özcan A.; Uysal S.; Yaliniz M.K.
    In the Central Sakarya area of Turkey there are two main Alpine continental units, separated by a south verging ophiolitic complex which represents the root zone of the Izmir-Ankara Suture Belt. The Central Sakarya Terrane in the north includes two 'Variscan' tectonic units in its basement. The Sogut Metamorphic rocks represent a Variscan ensimatic arc complex and the Tepekoy Metamorphic rocks are characteristically a forearc-trench complex. The unconformably overlying Triassic Sogukkuyu Metamorphic rocks correspond to a part of the Karakaya Formation and are interpreted as a Triassic rift basin assemblage. These units are unconformably overlain by a transgressive sequence of Liassic-Late Cretaceous age that represents the northeastward deepening carbonate platform of the Sakarya Composite Terrane. The middle tectonic unit (the Central Sakarya Ophiolitic Complex) comprises blocks and slices of dismembered ophiolites, blueschists and basic volcanic rocks with uppermost Jurassic-Lower Cretaceous radiolarite-limestone interlayers. Geochemical data from basalt blocks suggest mid-ocean ridge basalt (MORB)- and suprasubduction-type tectonic settings within the Neotethyan Izmir-Ankara Ocean. The southern tectonic unit includes basal polyphase metamorphosed clastic rocks (Somdiken Metamorphics), intruded by felsic and basic dykes and overlain by thickbedded marbles. This assemblage is unconformably overlain by continental clastic rocks gradually giving way to thick-bedded recrystallized limestones, cherty limestones and pelagic limestones intercalated with radiolarites, and finally by a thick high pressure-low temperature (HP-LT) metamorphic synorogenic flysch sequence. This succession is identical to the passive continental margin sequences of the Tauride Platform. It is suggested that this passive margin was subducted during the Late Cretaceous in an intra-oceanic subduction zone and affected by HP-LT metamorphism. The emplacement of the allochthonous oceanic assemblages and the collision with the Central Sakarya Terrane was complete by the end of the Cretaceous.
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    Gastrointestinal stromal tumors: A multicenter study of 1160 Turkish cases
    (2012) Bülbül Doǧusoy G.; Akalin T.; Tunçyürek M.; Kapran Y.; Doran F.; Dursun A.; Ensari A.; Gedikoǧlu G.; Saǧol Ö.; Özoran Y.; Pak I.; Yavuzer D.; Soyuer I.; Yavuz H.; Güneş P.; Sakiz D.; Behzatoǧlu K.; Ekinci N.; Arikök A.T.; Yerci Ö.; Gürbüz Y.; Kayaselçuk F.; Ayhan S.; Turhan N.; Özdamar Ş.
    Background/aims: The aim of this multicenter study was to determine the histopathological features and immunohistochemical profiles of gastrointestinal stromal tumors diagnosed in Turkish patients. Material and Methods: Twenty-eight participating centers registered their gastrointestinal stromal tumor cases on a nationwide database. The diagnosis of gastrointestinal stromal tumor relied upon hematoxylin & eosin features and the results of antibody panel including CD117, CD34, desmin, smooth muscle actin, S-100 protein, and Ki67. The database consisted of parameters including age, gender, location, and all other histopathological and immunohistochemical findings. Statistical analysis was performed using Pearson, Kruskal-Wallis, Mann-Whitney U, and Spearman tests. Results: From all of the gastrointestinal stromal tumors in the database, 1160 cases with a male to female ratio of 1.22 and a mean age of 56.75 years were included in the study. The most common location was the stomach (45.0%), followed by the small intestine, omentum-peritoneum, large intestine, and esophagus (32.0%, 12.6%, 9.3%, 1.1%, respectively). The risk groups were distributed as: 6.1% very low, 21.7% low, 19.3% intermediate, and 53% high-risk cases. Many histopathologic findings were correlated with risk groups. CD117 was positive in 95.3% of gastrointestinal stromal tumors, whereas CD34 was positive in 74.9%, smooth muscle actin in 45.9%, desmin in 9.2%, and S-100 in 19.1.%. Though no significant relation was found between CD117 expression and tumor location, CD34, smooth muscle actin and Ki67 expressions significantly varied in different locations (p=0.001) and risk groups. Conclusions: The results of this multicenter study demonstrated that features other than tumor size and mitosis and immune markers other than CD117 and Ki67 included in the antibody panel seem to be useful as predictive risk factors.
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    A retrospective evaluation of the epithelial changes/lesions and neoplasms of the Gallbladder in Turkey and a review of the existing sampling methods: A multicentre study
    (Federation of Turkish Pathology Societies, 2018) Esendağli G.; Akarca F.G.; Balci S.; Argon A.; Şengiz Erhan S.; Turhan N.; İnce Zengin N.; Hallaç Keser S.; Çelik B.; Bulut T.; Abdullazade S.; Erden E.; Savaş B.; Bostan T.; Sağol Ö.; Aysal Ağalar A.; Kepil N.; Karslioğlu Y.; Günal A.; Markoç F.; Saka B.; Özgün G.; Özdamar Ş.O.; Bahadır B.; Kaymaz E.; Işık E.; Ayhan S.; Tunçel D.; Özgüven Yılmaz B.; Çelik S.; Karabacak T.; Erbarut Seven İ.; Ataizi Çelikel Ç.; Gücin Z.; Ekinci Ö.; Akyol G.
    Objective: As there is continuing disagreement among the observers on the differential diagnosis between the epithelial changes/lesions and neoplasms of the gallbladder, this multicentre study was planned in order to assess the rate of the epithelial gallbladder lesions in Turkey and to propose microscopy and macroscopy protocols. Material and Method: With the participation of 22 institutions around Turkey that were included in the Hepato-Pancreato-Biliary Study Group, 89,324 cholecystectomy specimens sampled from 2003 to 2016 were retrospectively evaluated. The numbers of adenocarcinomas, dysplasias, intracholecystic neoplasms/adenomas, intestinal metaplasias and reactive atypia were identified with the review of pathology reports and the regional and countrywide incidence rates were presented in percentages. Results: Epithelial changes/lesions were reported in 6% of cholecystectomy materials. Of these epithelial lesions, 7% were reported as adenocarcinoma, 0.9% as high-grade dysplasia, 4% as low-grade dysplasia, 7.8% as reactive/regenerative atypia, 1.7% as neoplastic polyp, and 15.6% as intestinal metaplasia. The remaining lesions (63%) primarily included non-neoplastic polypoids/hyperplastic lesions and antral/pyloric metaplasia. There were also differences between pathology laboratories. Conclusion: The major causes of the difference in reporting these epithelial changes/lesions and neoplasms include the differences related to the institute’s oncological surgery frequency, sampling protocols, geographical dissimilarities, and differences in the diagnoses/interpretations of the pathologists. It seems that the diagnosis may change if new sections are taken from the specimen when any epithelial abnormality is seen during microscopic examination of the cholecystectomy materials. © 2018, Federation of Turkish Pathology Societies. All rights reserved.