Aims: The classification of paediatric spindle mesenchymal tumours is evolving, and the spectrum of socalled 'infantile fibrosarcoma' has expanded to include tumours with NTRK, BRAF and MET gene fusions. RETrearranged paediatric spindle cell neoplasms are an emerging group; there is sparse literature on their clinical, pathological and genetic features, and their nosological place in the canon of soft tissue tumours is uncertain. In this study, we report five RET-rearranged paediatric spindle cell tumours with fusion partners MYH10, KIAA1217 and CLIP2. Methods and results: The tumours occurred in the pelvic region, paraspinal region, kidney and subcutaneous tissue of hand and abdomen. The patients' ages ranged from 6 months to 13 years (median 1 year). The tumours were composed of monomorphic spindle cells arranged in a fascicular pattern. Lesional cells had minimally atypical ovoid or tapered nuclei and pale cytoplasm with indistinct borders. Necrosis was not identified. Mitoses numbered three to 12 per 10 high-power field. Cases showed inconsistent and variable expression of S100, CD34 and SMA. Clinical behaviour ranged from small lesions potentially cured by simple resection to large lesions exhibiting metastasis, but responsive to kinase inhibitor therapy. Conclusions: Our findings help to define RET-rearranged spindle cell tumours. Although it is likely that these tumours comprise part of the morphological and clinical spectrum of infantile fibrosarcoma (IFS), identification of RET gene alteration is important for its unique therapeutic implications.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has induced a tremendous toll on our health care system and society, but the rapid development of effective vaccines using novel mRNA technology in less than 1 year represents an unprecedented scientific achievement. In December 2020, the Pfizer-BioNTech (New York, NY, USA and Mainz, Germany) (BNT162b2) and Moderna (Cambridge, MA, USA) (mRNA-1273) vaccines were approved by the US Food and Drug Administration under an Emergency Use Authorization based on phase 2/3 clinical trial data showing high efficacy in preventing symptomatic SARS-CoV-2 infection with a favorable safety profile in more than 70,000 individuals, but recipients of immunosuppressive medications, including liver transplantation (LT) recipients, were excluded from the trials. (1,2) In this setting of rapid deployment, little is known of the efficacy and potential risks of novel SARS-CoV-2 vaccination in LT recipients. We report an episode of steroid-resistant acute cellular rejection (ACR) in an LT recipient occurring after the first dose of the Moderna vaccine.

BACKGROUND Balanced resuscitation strategies have led to increased utilization of plasma. Fresh frozen plasma that is thawed and never used is a large source of blood component wastage. Thawed plasma (TP) and can only be stored for 5 days. Liquid plasma (LP) has never been frozen and can be stored for 26 days. Due to longer storage duration, we hypothesized that using LP would result in decreased waste and cost savings compared with TP. METHODS We performed a retrospective review of all trauma patients at our Level I trauma center in the years 2015 to 2016. We compared 2015 when only TP was used to 2016 when both TP and LP were used. All plasma units ordered for trauma patients were tracked until the time of transfusion or wastage. Wastage rates were compared between years and plasma type. RESULTS There were 5,789 trauma patients admitted to our institution from 2015 to 2016. There were 4,107 plasma units ordered with 487 (11.9%) units wasted. During 2015, 2,021 total units of plasma were ordered with 273 (13.5%) units wasted which was a significantly higher rate than 2016 when 2,086 total units of plasma were ordered and 214 (10.3%) units were wasted (p = 0.0013). During 2016, 1,739 units of TP were ordered and 204 (11.7%) units were wasted which was significantly higher than LP wastage, 347 units ordered and 10 (2.9%) units wasted (p < 0.001). Of the 477 wasted TP units, 76.9% were ordered no more than two times before being wasted and 95.8% were ordered no more than three times before being wasted. Of the 10 LP units wasted, 40% were ordered no more than two times before being wasted, and 50% were ordered no more than three times before being wasted. If TP was wasted at the same rate as LP, 368 fewer units of plasma would have been wasted representing US $39,376 (US $107/unit) of wasted health care expenses. CONCLUSION At a Level I trauma center, the addition of LP to the blood bank for trauma resuscitations significantly reduced plasma wastage rates and health care expenses. LEVEL OF EVIDENCE Level III, Economic/Decision.

The COVID-19 pandemic has forced educational programs, including pathology residency, to move to a physically distanced learning environment. Tandem microscopic review (also known as “double-scoping”) of pathology slides is a traditional cornerstone of pathology education. However, this requires the use of a double- or multi-headed optical light microscope which is unfortunately not amenable to physical distancing. The loss of double-scoping has forced educational innovation in order to continue teaching microscopy. Digital pathology options such as whole slide imaging could be considered; however, financial constraints felt by many departments often render this option cost-prohibitive. Alternatively, a shift toward teaching via dynamic virtual microscopy offers a readily available, physically distanced, and cost-conscious alternative for pathology education. Required elements include a standard light microscope, a mounted digital camera, computers, and videoconferencing software to share a slide image with the learner(s). Through survey data, we show immediate benefits include maintaining the essence of the traditional light microscope teaching experience, and additional gains were discovered such as the ability for educators and learners to annotate images in real time, among others. Existing technology may not be initially optimized for a dynamic virtual experience, resulting in lag time with image movement, problems focusing, image quality issues, and a narrower field of view; however, these technological barriers can be overcome through hardware and software optimization. Herein, we share the experience of establishing a dynamic virtual microscopy educational system in response to the COVID-19 pandemic, utilizing readily available technology in the pathology department of a major academic medical center.