Jiří Sláma

High false negative rate of frozen section examination of sentinel lymph nodes in patients with cervical cancer

OBJECTIVES Metastatic involvement of the sentinel nodes (SN) is one of the main prognostic factors in cervical cancer which determines the disease management. The results of intra-operative SN examination would make it possible to triage patients in a one-step protocol. The studies carried out on the subject so far have, however, failed to demonstrate adequate accuracy of frozen section examination (FS) and, moreover, they only involved small cohorts. METHODS The study included 225 patients with cervical cancer FIGO IA2-IIB in whom at least one SN has been detected and intra-operatively processed. The prevalence of macrometastases, micrometastases and isolated tumour cells (ITC) in the SN was evaluated and the results of FS and final SN ultrastaging were compared. RESULTS Metastatic involvement of the SN was detected by pathologic ultrastaging in 73 cases (32.4%); macrometastases, micrometastases and ITC were found in 48, 17 and 8 patients, respectively. Intra-operative SN assessment established the SN status correctly in as few as 41 cases (56.2%), or in 49 cases (63%) if ITC had been excluded. Final ultrastaging of intra-operatively negative SN confirmed macrometastases, micrometastases, and ITC in additional 8, 18 and 8 patients, respectively. The false negative rate of FS was higher in bigger tumours (>20 cm3) and in the presence of LVSI. CONCLUSIONS Frozen section examination of SN is not sufficiently reliable; it has a high false negative rate mainly due to its limited ability to detect micrometastases. A possible solution would be a more detailed intra-operative pathologic processing or two-step surgical management.

U–Pb zircon provenance of Moldanubian metasediments in the Bohemian Massif

Detrital zircon U–Pb age data from the Moldanubian part of the Bohemian Massif obtained by laser ablation inductively coupled plasma mass spectrometry show variations between the lithotectonic units and point to their formation in spatially close but separated basins that were supplied by detritus from somewhat different source areas, possibly over different periods of time. The youngest detrital zircon component in metasediments of the Monotonous and Varied Units is Early Ordovician and Mid- to Late Devonian in age, respectively, suggesting their deposition in Palaeozoic times. Reliable interpretation of the Mid- to Late Devonian zircons recovered from metasediments of the Gföhl Unit is precluded by their high metamorphic grade and presence of anatectic melt. The Early Carboniferous zircons from the Gföhl Unit are interpreted as being of metamorphic origin. Comparison of detrital zircon age spectra from the Moldanubian, Teplá–Barrandian and Moravo-Silesian metasediments suggests that these were deposited in separate basins but the overall similarity of the Neoproterozoic and Palaeoproterozoic age maxima and sparse Neo- and Mesoarchaean ages suggest that the three crustal segments must have been spatially related prior to the Variscan orogeny. Future tectonic models of the Variscan assembly of the Bohemian Massif must account for nearly synchronous evolution of the Moldanubian, Teplá–Barrandian and Moravo-Silesian Palaeozoic sedimentary basins that shared a common crust and most of their sedimentary sources, as well as for a rapid burial of the Moldanubian sediments to mid- and lower crustal levels that was followed by their rapid exhumation to the upper crust in Mid-Devonian to Early Carboniferous times. Supplementary material: Results of LA-ICP-MS U–Pb analyses of zircons extracted from the Moldanubian and Moravo-Silesian metasediments are available at www.geolsoc.org.uk/SUP18676.

Mineral fabrics in high-level intrusions recording crustal strain and volcano–tectonic interactions: the Shellenbarger pluton, Sierra Nevada, California

The Minarets caldera is a volcano–plutonic complex in the Sierra Nevada, California, that exemplifies complex interactions between volcanism and tectonic deformation in continental-margin arcs. Caldera evolution commenced with emplacement of pre-collapse rhyolitic ash-flow tuff, followed by collapse and deposition of volcanic breccia and rhyodacitic ash-flow tuff. Subsequently, the volcanic rocks were deformed along the regional Bench Canyon shear zone. The caldera centre was then intruded by the resurgent c. 100 Ma steep-sided Shellenbarger granite pluton, which steepened the shear zone foliation. The pluton was overprinted by syn- to post-magmatic ∼NNE–SSW horizontal shortening; the same shortening was documented in several other Late Cretaceous syntectonic plutons in the Sierra Nevada and interpreted to record dextral transpression during convergence of the Farallon and North American plates. To explain the unusual tectonic fabric in the shallow-level Shellenbarger pluton, we develop a general model for strain partitioning in syntectonic magma bodies emplaced at various crustal levels. We propose that shallow intrusions, isolated within stiff crust, may tend to accommodate minor pure shear strain whereas simple shear dominates along weak faults and shear zones. By contrast, a rheological reversal is crossed deeper in the crust and magma bodies become the weakest, simple shear-dominated parts of the system. Supplementary material: Analytical methods and anisotropy of magnetic susceptibility and U–Th–Pb isotopic data are available at https://doi.org/10.6084/m9.figshare.c.3582749

Rapid extensional unroofing of a granite–migmatite dome with relics of high-pressure rocks, the Podolsko complex, Bohemian Massif

The Podolsko complex, Bohemian Massif, is a high-grade dome that is exposed along the suprastructure–infrastructure boundary of the Variscan orogen and records snapshots of its protracted evolution. The dome is cored by leucocratic migmatites and anatectic granites that enclose relics of high- to ultrahigh-pressure rocks and is mantled by biotite migmatites and paragneisses whose degree of anatexis decreases outwards. Our new U–Pb zircon ages indicate that the leucocratic migmatites were derived from Early Ordovician ( c. 480 Ma) felsic igneous crust; the same age is inferred for melting the proto-source of the metapelitic migmatites. The relics of high- to ultrahigh-pressure rocks suggest that at least some portions of the complex witnessed an early Variscan subduction to mantle depths, followed by high-temperature anatexis and syntectonic growth of the Podolsko dome in the middle crust at c. 340–339 Ma. Subsequently, the dome exhumation was accommodated by crustal-scale extensional detachments. Similar c. 340 Ma ages have also been reported from other segments of the Variscan belt, yet the significance of this tectonothermal event remains uncertain. Here we conclude that the 340 Ma age post-dates the high-pressure metamorphism; the high temperatures required to cause the observed isotopic resetting and new growth of zircon were probably caused by heat input from the underlying mantle and, finally, the extensional unroofing of the complex requires a minimum throw of about 8–10 km. We use this as an argument for significant early Carboniferous palaeotopography in the interior of the Variscan orogen.

How far did the Cadomian ʽterranesʼ travel from Gondwana during early Palaeozoic? A critical reappraisal based on detrital zircon geochronology

ABSTRACT In this paper, laser ablation ICP-MS U–Pb detrital zircon ages are used to discuss provenance and early Palaeozoic palaeogeography of continental fragments that originated in the Cadomian–Avalonian active margin of Gondwana at the end of Precambrian, were subsequently extended during late Cambrian to Early Ordovician opening of the Rheic Ocean, and finally were incorporated into and reworked within the European Variscan belt. The U–Pb detrital zircon age spectra in the analysed samples, taken across a late Neproterozoic (Ediacaran) to Early/Middle Devonian metasedimentary succession of the southeastern Teplá–Barrandian unit, Bohemian Massif, are almost identical and exhibit a bimodal age distribution with significant peaks at about 2.1–1.9 Ga and 650–550 Ma. We interpret the source area as an active margin comprising a cratonic (Eburnean) hinterland rimmed by Cadomian volcanic arcs and we suggest that this source was available at all times during deposition. The new detrital zircon ages also corroborate the West African provenance of the Teplá–Barrandian and correlative Saxothuringian and Moldanubian units, questioned in some palaeogeographic reconstructions. Finally, at variance with the still popular concept of the Cadomian basement units as far-travelled terranes, we propose that early Palaeozoic basins, developed upon the Cadomian active margin, were always part of a wide Gondwana shelf and drifted northwards together before involvement in the Variscan collisional belt.

Depositional history of a condensed shallow marine reservoir succession: stratigraphy and detrital zircon geochronology of the Jurassic Stø Formation, Barents Sea

The Early to Middle Jurassic Stø Formation (Toarcian to Bajocian) was deposited in a relatively shallow (10 s of meter deep) epicontinental sea in northern Pangea and represents one of the most prolific reservoir intervals in the Barents Sea basin. It comprises a condensed, predominantly shallow marine succession characterized by long hiatuses and erosional reworking with several horizons of extraformational pebble grade conglomerate. Six distinct facies associations describe sedimentological environments ranging from transgressive, tidal, fluvial and regressive shoreface. Deposits are interpreted and correlated within three sequence stratigraphic units (SI to SIII) which reflect variations in relative sea-level during an overall transgression of the basin. Interpreted depositional systems show subtle variations in petrographic character, but provenance analyses reveal different sedimentary sources. Thirteen core samples distributed geographically and stratigraphically were analysed for detrital zircon U-Pb geochronology. Data show that the Southwestern Barents Sea Basin (SWBSB) was dominated by mixing of reworked material and coarse grained sediment supply from extrabasinal source areas including a Caledonian provenance in the southwest and a Fennoscandian provenance to the southeast. Intra-basinal erosion of underlying strata with Triassic zircon grains dominate in northern parts of the basin. Supplementary material: Supporting information relating to the analysis of different dataset and the interpretations presented in the paper are available at https://doi.org/10.6084/m9.figshare.c.3841282.

Anogenital HPV Infection as the Potential Risk Factor for Oropharyngeal Carcinoma

BACKGROUND Human papillomavirus (HPV) can cause cervical, other genital, anal, head, and neck cancers. The incidence of oropharyngeal squamous cell carcinoma (OSCC), the head and neck cancer most commonly caused by HPV infection, is increasing. The prevalence of oral HPV infections is considerably lower than that of genital HPV infections; however, infection of both sites is strongly associated with sexual behavior. Although the natural histories of cervical and oral HPV infections do not markedly differ, the virus seems to rarely infect oral and genital sites simultaneously. On the other hand, the standardized incidence ratio of OSCC is higher in cervical cancer patients than in other populations. Furthermore, women with OSCC have a significantly increased risk of developing HPV-related genital cancers. Administration of the HPV vaccine to both genders will undoubtedly dramatically change the epidemiology of HPV-related cancers. AIM This work provides an overview of the literature and estimates the risk of OSCC in women with anogenital HPV infections. CONCLUSION The biological relationship between different HPV-infected sites might be complex; however, the increased prevalence of HPV in oral samples of women positive for anogenital HPV indicates that such infections are unlikely to be independent of one another. Sexual activity likely affects the risk of concurrent anogenital and oral coinfections. However, it is also possible that one infection site provides a reservoir that can increase the risk of autoinoculation at anatomically distant locations or that coinfections develop as a result of other factors, such as immunodeficiency. Nevertheless, women with HPV-associated malignancy undoubtedly have a higher risk of developing OSCC.Key words: human papillomavirus - HPV - genital HPV infection - oral HPV infection - oropharyngeal squamous cell carcinoma - standardized incidence ratio - head and neck cancer This article was supported by by the project UNCE 204065 of Charles University. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 26. 8. 2017Accepted: 4. 1. 2018.