Primary extra-cranial meningioma in the right submandibular region of an 18-year-old woman: a case report

<p>Abstract</p> <p>Introduction</p> <p>Extra-cranial meningioma or ectopic meningioma is a rare tumor. This tumor has been reported in various anatomic sites in the head and neck, mediastinum, skin and soft tissues. We report a rare case of ectopic meningioma in the submandibular region detected by using fine-needle aspiration cytology, histopathology and immunohistochemistry. This case represents another unusual site for extra-cranial meningioma, which prompted us to report it.</p> <p>Case presentation</p> <p>An 18-year-old Dravidian woman presented with swelling in the right submandibular region. The computed tomographic scan findings were suggestive of a neoplastic mass lesion in the right submandibular region. Fine-needle aspiration cytology led to the differential diagnosis of a monomorphic adenoma of a salivary gland or an ectopic meningioma. The patient underwent excision of the submandibular gland and tumor. The histological examination and immunohistochemistry studies confirmed that the lesion was an extra-cranial meningioma. At her two-year follow-up examination, there was no recurrence of the tumor.</p> <p>Conclusion</p> <p>Our experience with this case indicates that, although rare, meningioma should be entertained in the differential diagnosis of a mass lesion in the head and neck region.</p

Epidemiology of intra-abdominal infection and sepsis in critically ill patients: “AbSeS”, a multinational observational cohort study and ESICM Trials Group Project

Purpose: To describe the epidemiology of intra-abdominal infection in an international cohort of ICU patients according to a new system that classifies cases according to setting of infection acquisition (community-acquired, early onset hospital-acquired, and late-onset hospital-acquired), anatomical disruption (absent or present with localized or diffuse peritonitis), and severity of disease expression (infection, sepsis, and septic shock). Methods: We performed a multicenter (n = 309), observational, epidemiological study including adult ICU patients diagnosed with intra-abdominal infection. Risk factors for mortality were assessed by logistic regression analysis. Results: The cohort included 2621 patients. Setting of infection acquisition was community-acquired in 31.6%, early onset hospital-acquired in 25%, and late-onset hospital-acquired in 43.4% of patients. Overall prevalence of antimicrobial resistance was 26.3% and difficult-to-treat resistant Gram-negative bacteria 4.3%, with great variation according to geographic region. No difference in prevalence of antimicrobial resistance was observed according to setting of infection acquisition. Overall mortality was 29.1%. Independent risk factors for mortality included late-onset hospital-acquired infection, diffuse peritonitis, sepsis, septic shock, older age, malnutrition, liver failure, congestive heart failure, antimicrobial resistance (either methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum beta-lactamase-producing Gram-negative bacteria, or carbapenem-resistant Gram-negative bacteria) and source control failure evidenced by either the need for surgical revision or persistent inflammation. Conclusion: This multinational, heterogeneous cohort of ICU patients with intra-abdominal infection revealed that setting of infection acquisition, anatomical disruption, and severity of disease expression are disease-specific phenotypic characteristics associated with outcome, irrespective of the type of infection. Antimicrobial resistance is equally common in community-acquired as in hospital-acquired infection

TOWARDS A PALAEOECOLOGICAL RECONSTRUCTION OF THE MIOCENE VERTEBRATE FAUNAS OF THE PISCO FORMATION (PERU): GLIMPSES INTO THE PAST OF THE HUMBOLDT CURRENT ECOSYSTEM

Flowing northwards along the western coast of South America, the Humboldt Current hosts extremely high levels of biological productivity all-year-round. With the aim of developing a deep-time investigation of this unique ecological setting, we provide the first synoptic overview of the palaeoecological habits of the fossil marine vertebrates of the Pisco Formation, a shallow-marine sedimentary unit of southern Peru that is renowned worldwide for its abundant and well-preserved Miocene fossil content. By building upon palaeontological data gathered on hundreds of fossils (including cetaceans, pinnipeds, seabirds, turtles, crocodiles, and bony and cartilaginous fishes), palaeoenvironmental conditions and palaeoecological relationships are thus reconstructed for the three sequences that comprise the Pisco Formation and their marine vertebrate assemblages. Some aspects of the Pisco palaeoecosystems are then investigated in detail, and similarities and differences are highlighted with respect to the present-day Humboldt Current Ecosystem and other extant Eastern Boundary upwelling systems. Like today, the southern Peruvian shelfal ecosystems witnessed by the Miocene Pisco strata were based on sardines, which are locally known from several fossils (including stomach contents). At the same time, they notably differed from their modern equivalent in being dominated by extremely large-bodied apex predators such as Livyatan melvillei and Carcharocles megalodon

Vertebrate palaeoecology of the Pisco Formation (Miocene, Peru): Glimpses into the ancient Humboldt Current Ecosystem

The northward-flowing Humboldt Current hosts perpetually high levels of productivity along the western coast of South America. Here, we aim to elucidate the deep-time history of this globally important ecosystem based on a detailed palaeoecological analysis of the exceptionally preserved middle–upper Miocene vertebrate assemblages of the Pisco Formation of the East Pisco Basin, southern Peru. We summarise observations on hundreds of fossil whales, dolphins, seals, seabirds, turtles, crocodiles, sharks, rays, and bony fishes to reconstruct ecological relationships in the wake of the Middle Miocene Climatic Optimum, and the marked cooling that followed it. The lowermost, middle Miocene Pisco sequence (P0) and its vertebrate assemblage testify to a warm, semi-enclosed, near-shore palaeoenvironment. During the first part of the Tortonian (P1), high productivity within a prominent upwelling system supported a diverse assemblage of mesopredators, at least some of which permanently resided in the Pisco embayment and used it as a nursery or breeding/calving area. Younger portions of the Pisco Formation (P2) reveal a more open setting, with wide-ranging species like rorquals increasingly dominating the vertebrate assemblage, but also local differences reflecting distance from the coast. Like today, these ancient precursors of the modern Humboldt Current Ecosystem were based on sardines, but notably differed from their present-day equivalent in being dominated by extremely large-bodied apex predators like Livyatan melvillei and Carcharocles megalodon

Taphonomy of marine vertebrates of the Pisco Formation (Miocene, Peru): insights into the origin of an outstanding Konzentrat- and Konservat-Lagerstätte

The Miocene Pisco Formation, broadly exposed in the Ica Desert of southern Peru, is among the most outstanding Cenozoic marine Fossil-Lagerstätten worldwide. It is renowned for its exceptional preservation and abundance of vertebrate fossils, including a rich assemblage of whales and dolphins (Cetacea). Here, we integrate taphonomic data on 890 marine vertebrate fossils, gathered through 16 different localities. Our observations range from the taxonomic distribution, articulation, completeness, disposition and orientation of skeletons, to the presence of bite marks, associations with shark teeth and macro-invertebrates, bone and soft tissue preservation, and the formation of attendant carbonate concretions and sedimentary structures. We propose that the exceptional preservation characterising many Pisco vertebrates, as well as their exceptionally high abundance, cannot be ascribed to a single cause like high sedimentation rates (as proposed in the past), but rather to the interplay of several favourable factors including: (i) low levels of dissolved oxygen at the seafloor (with the intervention of seasonal anoxic events); (ii) the early onset of mineralisation processes like apatite dissolution/recrystallisation and carbonate mineral precipitation; (iii) rapid burial of carcasses in a soupy substrate and/or a novel mechanism involving scour-induced self- burial; and (iv) original biological richness. Collectively, our observations provide a comprehensive overview of the taphonomic processes that shaped one of South America’s most important fossil deposits, and suggest a model for the formation of other marine vertebrate Fossil-Lagerstätten

Allostratigraphy and paleontology of the lower Miocene Chilcatay Formation in the Zamaca area, East Pisco basin, southern Peru

Based on mapping of laterally traceable stratigraphic discontinuities, we propose a high-resolution allostratigraphic scheme for one of the world’s foremost fossil marine vertebrate Lagerstätten: the lower Miocene strata of the Chilcatay Formation exposed along the Ica River near Zamaca, southern Peru. Measured sections combined with 1:10,000 scale mapping of a 24 km2 area provide an overview of the stratal architecture, as well as a general facies framework and interpretation of the various depositional settings. As a whole, the Chilcatay alloformation is bounded by the CE0.1 unconformity at the base and the PE0.0 unconformity at the top. An internal Chilcatay surface, termed CE0.2, splits the alloformation into two distinct allomembers (Ct1 and Ct2). The Ct1 allomember comprises three facies associations recording deposition in shoreface, offshore, and subaqueous delta settings. The Ct2 allomember comprises two facies associations, recording deposition in shoreface and offshore settings. Using these data, we place the rich marine vertebrate assemblage in a precise spatial and stratigraphic framework. The well-diversified vertebrate assemblage is dominated by cetaceans (mostly odontocetes) and sharks (mostly lamniforms and carcharhiniforms); rays, bony fish, and turtles are also present. Taxonomic novelties include the first records of baleen whales, platanistids, and eurhinodelphinids from the Chilcatay Formation

Did the giant fossil shark Carcharocles megalodon eat small prey? Insights from bitten mammalian bones from the late Miocene of Peru.

Unlike bony fish, sharks are K-selected animals whose life history strategies generally include the use of protected nursery areas by young of the year and juveniles. Nursery areas can be primary (i.e., grounds where the sharks are born and spend the very first part of their lives) or secondary (i.e., grounds inhabited by slightly older but not yet adolescent or mature individuals). Criteria utilized to recognize and define these strategic habitats include: high concentration of young sharks, continuous or repeated use on various temporal scales, high food availability, and low predation risk. Since the fossil record of sharks is mainly composed of isolated teeth, identification of paleo-nurseries involves a series of problems due to difficult application of the above reported criteria. In fact, only four putative shark paleo-nurseries have been individuated to date: three of them regard lamniform sharks and were proposed on the basis of a few isolated small-sized teeth, whereas the fourth one comprises hybodontid and xenacanthid taxa and is testified by both selachian eggs and juvenile teeth. In the upper Miocene (Tortonian) deposits of the Pisco Formation exposed at Cerro Colorado (South Peru), a very rich shark tooth bearing level has recently been discovered. About 80% of the teeth collected from this level belong to the extant copper shark Carcharhinus brachyurus (Chondrichthyes: Carcharhinidae). These teeth are small-sized and compatible with extant individuals ranging from 80 cm to 210 cm in total length (i.e., immature and subadult copper sharks ranging in age between 4 and 16 years); adult teeth of C. brachyurus are in turn completely absent (although they are known from other Neogene deposits of Southeast Pacific, including a single site of the Pisco Formation). By analyzing the paleoenvironment of the Cerro Colorado shark tooth bearing level, we found that it meets the ecological criteria for individuating extant shark nurseries. The absence of very small-sized teeth (i.e., teeth referable to neonates and young of the year) allows us to hypothesize a secondary nursery ground inhabited by preadolescent copper sharks. The teeth size distribution of other chondrichthyan taxa (Lamniformes, Carcharhiniformes, and Myliobatiformes) that occur along with C. brachyurus put in evidence a significantly juvenile composition of the fossil shark assemblage, thus supporting the hypothesis of a communal use of the Cerro Colorado paleo-nursery by various mesopredator shark species. This study resulted in the identification of the first paleo-nursery for a carcharhiniform taxon, as well as in the first fossil shark nursery investigated with an ecology-based, actualistic approach

TAPHONOMY OF THE PISCO KONZENTRAT- AND KONSERVATLAGERSTÄTTE (MIOCENE, PERU)

Among the most outstanding Cenozoic marine Fossil-Lagerstätten worldwide, the Peruvian Pisco Formation is renowned for its exceptional preservation and abundance of fossil vertebrates, especially cetaceans. We present an updated overview and interpretation of taphonomic data gathered during fifteen field campaigns (2006-2019) on 890 fossil marine vertebrates from the Miocene strata of the Pisco Formation exposed in the Ica Desert. In order to assess the factors that led to the formation of such an exceptional Konzentrat- and Konservat-Lagerstätte, we made observations that range from the taxonomic distribution, articulation, completeness, disposition and orientation of skeletons, to the presence of bite marks, associations with shark teeth and macroinvertebrates, bone and soft tissue (i.e., baleen) preservation, and the formation of attendant carbonate concretions and sedimentary structures. We propose that the exceptional preservation and abundance of the Pisco Formation specimens cannot be ascribed to a single cause, but rather to the interplay of favorable palaeoenvironmental factors and suitable timing of mineralizing processes, such as: i) low concentration of dissolved oxygen at the seafloor; ii) the early onset of mineralization processes; iii) rapid burial of the carcasses; and iv) original biological richness in the southeastern Pacific. Our observations provide a comprehensive overview of the taphonomic characteristics of one of the most significant fossiliferous deposits of South America and lead to the elaboration of a complex scenario for the preservation of its marine vertebrates that might serve as a reference for explaining the formation of other marine vertebrate Fossil-Lagerstätten worldwide