Introduction: Gastric submucosal lesions are a common finding during endoscopy. However, they rarely present as or cause any symptoms. We present an interesting and rare case of a gastric submucosal lesion causing symptoms Case Description/Methods: An 82-year-old woman with multiple comorbidities presented with worsening nausea and abdominal pain and early satiety. Physical examination had no findings of abdominal tenderness or a palpable mass. A contrast enhanced computed tomography (CT) scan was then performed, and a 6.2cm x 4.9 cm gastric mass was noted. (Figure a) An upper endoscopy revealed an extrinsic compression in the gastric antrum. An endoscopic ultrasound(EUS) examination was then performed, and on EUS, a large perigastric mass in the distal stomach was noted. The lesion appeared hypoechoic and measured 4.6 x 4.9cm with minimal amount of vascularity under EUS-doppler. (Figure b) Transgastric biopsies were obtained. Final pathology revealed spindle cell neoplasm with myxoid stroma, most consistent with schwannoma. The immunohistochemical profile was consistent with schwannoma (Figure c). The patient then underwent surgical resection (Figure d) and pathology confirmed a gastric schwannoma Discussion: Schwannomas are spindle cell mesenchymal tumors originating from the Schwann cell sheath. Gastric schwannomas arise from the gastrointestinal neural plexus. Gastric schwannomas are typically benign and incidentally found, but rarely can have malignant transformation. The tumors are predominantly found in middle-aged females. Gastric schwannoma usually presents in the gastric body. It is important to distinguish these tumors from the two other types of mesenchymal tumors, such as gastrointestinal stromal tumors and leiomyoma. Schwannomas typically have a spindle cell pattern with vague nuclear palisading and peritumoral lymphoid cuff without encapsulation with S100 positive staining and negative for CD34 and CD117, which differentiates them from gastrointestinal stromal tumors and autonomic nerve tumors. Schwannomas stain negatively for actin, unlike leiomyomas. Treatment is typically surgery with recurrence rarely described. The type of surgical approach is dependent on tumor size and location. Due to the excellent outcomes, some endoscopic options are also considered safe Our patient did well and on follow had resolution of all prior symptoms. This case report illustrates the importance of the consideration of schwannomas in the differential diagnosis of perigastric and submucosal lesionsFigure 1.: a: CT scan appearance of the perigastric mass; b: Mass as seen on EUS; c: Pathology with S100 staining; d: Resected specimen.
Abstract The Mw 6.4 and Mw 7.1 Ridgecrest earthquake sequence occurred on 4 and 5 July 2019 within the eastern California shear zone of southern California. Both events produced extensive surface faulting and ground deformation within Indian Wells Valley and Searles Valley. In the weeks following the earthquakes, more than six dozen scientists from government, academia, and the private sector carefully documented the surface faulting and ground-deformation features. As of December 2019, we have compiled a total of more than 6000 ground observations; approximately 1500 of these simply note the presence or absence of fault rupture or ground failure, but the remainder include detailed descriptions and other documentation, including tens of thousands of photographs. More than 1100 of these observations also include quantitative field measurements of displacement sense and magnitude. These field observations were supplemented by mapping of fault rupture and ground-deformation features directly in the field as well as by interpreting the location and extent of surface faulting and ground deformation from optical imagery and geodetic image products. We identified greater than 68 km of fault rupture produced by both earthquakes as well as numerous sites of ground deformation resulting from liquefaction or slope failure. These observations comprise a dataset that is fundamental to understanding the processes that controlled this earthquake sequence and for improving earthquake hazard estimates in the region. This article documents the types of data collected during postearthquake field investigations, the compilation effort, and the digital data products resulting from these efforts.
Abstract The San Gorgonio Pass region of southern California is a locus of extensive Quaternary deformation within a multi-strand section of the San Andreas fault zone. The geomorphology of the San Gorgonio Pass region reflects the complicated history of geologic events in the formation of this structurally complex region. We define fault-bounded blocks in San Gorgonio Pass and focus on two that are characterized by extensive crystalline bedrock outcrops with similar bedrock lithologies. These two blocks are separated by the San Bernardino strand of the San Andreas fault. Morphometric variables, including local relief, slope, slope distribution, and surface roughness, consistently demonstrate distinctions between the bedrock upland regions of the two blocks. Geologic observations of the region highlight differences in Quaternary units within the two blocks, reflective of the differing surficial processes active in each block. Within the Kitching Peak block, the morphology highlights a lineament that we informally name the Lion Canyon lineament. This boundary more clearly differentiates the two regions, as compared to the mapped San Bernardino strand, and may represent the previously active strand or bounding structure in this section. The distinction in morphology and surficial processes leads to our interpretation that the Kitching Peak and Pisgah Peak blocks have experienced different uplift histories. This further leads to the conclusion that the San Bernardino strand, broadly defined, has been integrated, at some point in the past, with the Banning strand, allowing for through-going rupture along the fault system. This connectivity may have occurred along the Burro Flats section of the San Bernardino strand or the Lion Canyon lineament. The fault connection along the mapped trace of the San Bernardino strand is not currently evident at the surface, however, suggesting that the integration has been disrupted. We propose this is due to intervals of N-S compression in the region, manifest as slip along the San Gorgonio Pass fault zone and other regional faults. We present evidence for lateral displacement along the San Bernardino and Banning strands of the San Andreas fault, discuss the implications of these displacements, and propose a sequence of fault activity, including multiple phases of activity along the San Bernardino and Banning strand pathway to account for the structural complexity and lack of surficial fault continuity.
