Resection margin involvement after endoscopic excision of malignant colorectal polyps: definition of margin involvement and its impact upon tumour recurrence.

AIMS: Malignant polyps are examined to assess histological features which predict residual tumour in the unresected bowel and guide surgical decision-making. One of the most important of these features is resection margin involvement, although the best definition of margin involvement is unknown. In this study we aimed to investigate three different definitions and determine their impact on clinical outcomes. METHODS AND RESULTS: One hundred and sixty-five malignant polyps removed endoscopically were identified and histological features correlated with either residual tumour in subsequent surgical resections or tumour recurrence following a period of clinical follow-up. Involvement of the polyp margin by cancer was defined in three different ways and outcomes compared. Tumour recurrence was associated with tumour grade, mucinous histology and resection margin involvement. All three definitions of margin involvement separated polyps into clinically significant categories; however, a margin ≤ 1 mm identified 73% of polyps as 'high-risk' compared with 59.1% when involvement was defined as tumour within the zone of coagulation artefact at the polyp base or 50% when tumour was present at the margin. All three 'low-risk' groups had a locoregional recurrence rate < 6.5%. CONCLUSIONS: Definitions of margin involvement for endoscopically removed malignant polyps in the colon and rectum vary between health-care systems, but a 1-mm clearance is widely used in Europe and North America. Our results suggest that a 1-mm margin is unnecessary and should be replaced by a definition based on tumour at the margin or within coagulation artefact at the polyp base.

Peer assessment: Development and delivery of the OSCE.

INTRODUCTION: There is an expectation that healthcare professionals display competence in teaching, assessment and providing feedback. Development begins with formative peer-assisted learning and teaching in the undergraduate environment. Using peers or near-peers (in this case having 1 year more experience than the examination cohort) to provide assessment in summative exams remains unexplored. This study investigates how the use of near-peers compares to marking by academic staff in a summative OSCE. MATERIALS AND METHODS: BDS4 Peer assessors (PAs) developed an OSCE question and marking schedule. Each PA (n = 3) was paired with an academic staff assessor (ASA) (n = 3). Peer and academic marked the candidates independently. Two years later, the process was repeated on the same cohort of candidates with the PA now 1-year post qualification. Statistical analysis compared the scores awarded by PA during each timeframe and against the marks awarded by the ASA. RESULTS: During round 1, 28 students (62.2%) were awarded the same score by PA and ASA. On 17 occasions, there was a discrepancy (37.8%). Bias was skewed in favour of PA scoring higher (mean difference of differences -0.0667). During round 2, 27 students (55.1%) were awarded the same score by PA and ASA. On 22 occasions (44.9%), there was a discrepancy. Bias was skewed in favour of ASA scoring higher (mean difference of differences 0.0612). DISCUSSION: Levels of agreement between PA and ASA are strong. Our results show PA mark more leniently as undergraduates and less leniently at 1-year post graduation. CONCLUSIONS: Peer assessors are able to write OSCE stations, produce marking schemes and effectively assess their near-peers.

The changing landscape of dental education - Glasgow Dental School.

Glasgow Dental School was set up in 1879, and since that time, dental education has been changing and evolving into the current landscape we recognise today. Changes in demographics and numbers of dental students have led to a more diverse community of students from wide and varied backgrounds. The years have also seen the development of educational theory and practice, and in more recent times, the introduction and expansion of digital and technology-enhanced learning and teaching have revolutionised the delivery of the dental curriculum. One of the most notable changes in the dental programme is the incorporation of student support, health and wellbeing. The modern dental course takes a more holistic approach to education, with the provision of training in generic and life skills, as well as the clinical skills required in an ever-expanding field. The demands and pressures of studying dentistry in the setting of modern, fast-paced life cannot be underestimated and the course must be ever-changing to reflect this. However, the one thing that has not changed is the enduring Glasgow Dental School community.

Is medullary carcinoma of the colon underdiagnosed? An audit of poorly differentiated colorectal carcinomas in a large national health service teaching hospital.

AIMS: Medullary carcinoma is an uncommon colorectal tumour which appears poorly differentiated histologically. Consequently, it may be confused with poorly differentiated adenocarcinoma not otherwise specified (NOS). The principal aim of this study was to review a large series of poorly differentiated colorectal cancers resected at a large National Health Service (NHS) Teaching Hospital to determine how often medullary carcinomas were misclassified . Secondary aims were to investigate how often neuroendocrine differentiation or metastatic tumours were considered in the differential diagnosis, and compare clinico-pathological features between medullary and poorly differentiated adenocarcinoma NOS. METHODS AND RESULTS: Histology slides from 302 colorectal cancer resections originally reported as poorly differentiated adenocarcinoma were reviewed and cases fulfilling World Health Organisation (WHO) criteria for medullary carcinoma identified. The original pathology report was examined for any mention of medullary phenotype, consideration of neuroendocrine differentiation or consideration of metastasis from another site. Clinico-pathological features were compared to poorly differentiated adenocarcinoma NOS. Only one-third of medullary carcinomas were correctly identified between 1997 and 2018. The other two-thirds were reported as poorly differentiated adenocarcinoma NOS. The possibility of an extracolonic origin or neuroendocrine carcinoma was considered in 21 and 27% of reports. Most medullary carcinomas exhibited mismatch repair deficiency, were located in ascending colon and caecum and had a lower rate of vascular channel invasion and lymph node metastasis compared to poorly differentiated adenocarcinoma. CONCLUSIONS: Medullary carcinoma of the colon is often mistaken for poorly differentiated adenocarcinoma NOS and occasionally for neuroendocrine or metastatic carcinoma. Greater familiarity with morphological criteria and use of mismatch repair protein staining should improve diagnosis.

Understanding dental students' use of feedback.

INTRODUCTION: Feedback can enhance learning and is thought to be highly valued by students; however, it is not clear from the literature how dental students actually use feedback. AIM: This study aimed to explore how dental students use feedback in a variety of contexts. METHODS: Qualitative methods involving audio-recorded focus groups were used to explore the use of feedback by undergraduate dental students studying at three UK dental schools. A purposive sampling strategy was used to ensure diverse representation across the undergraduate dental programmes in each of the schools. RESULTS: Six focus groups, involving a total of 72 students, were undertaken. Thematic analysis identified five main themes relating to the use of feedback: value, future applicability, accessibility, variability and understanding. The inter-connectivity and interaction of the themes (along with their subthemes) were used to develop a model for optimising feedback with the aim of enhancing its potential use by students. CONCLUSION: The use of feedback by students would appear to be strongly influenced by several factors. Understanding these factors and how they interlink may be helpful to education providers who are seeking to optimise their feedback processes.

PREFORMED METAL CROWNS FOR THE PERMANENT DENTITION.

Preformed metal crowns have a range of uses in paediatric dentistry in both the primary and permanent dentition. This article provides an overview of their use in permanent teeth, including teeth that have been affected by molar incisor hypomineralisation, caries, developmental defects and tooth surface loss. The indications for use are described, along with the clinical technique for placement

A matched-pair analysis of laparoscopic versus open pancreaticoduodenectomy: oncological outcomes using Leeds Pathology Protocol.

BACKGROUND: Laparoscopic pancreaticoduodenectomy (LPD) is a safe procedure. Oncological safety of LPD is still a matter for debate. This study aimed to compare the oncological outcomes, in terms of adequacy of resection and recurrence rate following LPD and open pancreaticoduodenectomy (OPD). METHODS: Between November 2005 and April 2009, 12 LPDs (9 ampullary and 3 distal common bile duct tumors) were performed. A cohort of 12 OPDs were matched for age, gender, body mass index (BMI) and American Society of Anesthesiologists (ASA) score and tumor site. RESULTS: Mean tumor size LPD vs OPD (19.8 vs 19.2 mm, P=0.870). R0 resection was achieved in 9 LPD vs 8 OPD (P=1.000). The mean number of metastatic lymph nodes and total number resected for LPD vs OPD were 1.1 vs 2.1 (P=0.140) and 20.7 vs 18.5 (P=0.534) respectively. Clavien complications grade I/II (5 vs 8), III/IV (2 vs 6) and pancreatic leak (2 vs 1) were statistically not significant (LPD vs OPD). The mean high dependency unit (HDU) stay was longer in OPD (3.7 vs 1.4 days, P<0.001). There were 2 recurrences each in LPD and OPD (log-rank, P=0.983). Overall mortality for LPD vs OPD was 3 vs 6 (log-rank, P=0.283) and recurrence-related mortality was 2 vs 1. There was one death within 30 days in the OPD group secondary to severe sepsis and none in the LPD group. CONCLUSIONS: Compared to open procedure, LPD achieved a similar rate of R0 resection, lymph node harvest and long-term recurrence for tumors less than 2 cm. Though technically challenging, LPD is safe and does not compromise oncological outcome.

Reality bites.

When milk teeth are replaced by adult teeth, it is crucial that a good oral health regime is maintained in order to prevent caries. Parents of infant school children should ideally supervise the twice daily cleaning regime to ensure nothing is missed. Older children and teenagers may be adversely influenced by their peers to eat sugary and other junk foods, but appealing to their vanity may work better rather than a lecture on disease prevention.

Pathology grading of colon cancer surgical resection and its association with survival: a retrospective observational study.

BACKGROUND: High-quality rectal cancer surgery is known to improve patient outcome. We aimed to assess the quality of colon cancer surgery by studying the extent of variation in the plane of surgical resection, the amount of tissue removed, and its association with survival. METHODS: All resections for primary colon adenocarcinoma done at Leeds General Infirmary (Leeds, UK) between Jan 1, 1997, and June 30, 2002, were identified. The specimens were photographed and graded according to the plane of mesocolic dissection. Tissue morphometry was done on 253 tumours. Univariate and multivariate models were used to ascertain whether there was an association with 5-year survival. The primary outcome measure was overall survival defined as death from any cause. FINDINGS: 521 cancers were identified, 122 were excluded because of either no photographic images or insufficient images to allow retrospective grading, leaving 399 specimens for analysis. There was marked variation in the proportion of each plane of surgery: muscularis propria in 95 of 399 (24%) specimens, intramesocolic in 177 of 399 (44%) specimens, and mesocolic in 127 of 399 (32%) specimens. Mean cross-sectional tissue area outside the muscularis propria was significantly higher with mesocolic plane surgery (mean 2181 [SD 895] mm(2)) compared with intramesocolic (mean 2109 [1273] mm(2)) and muscularis propria plane (mean 1447 [913] mm(2)) surgery (p=0.0003). There was also a significant increase in the distance from the muscularis propria to the mesocolic resection margin with mesocolic plane surgery (mean 44 [21] mm) compared with intramesocolic (mean 30 [16] mm) and muscularis propria plane (mean 21 [12] mm) surgery, which was independent of tumour site (all excisions p<0.0001). We noted a 15% (95% CI) overall survival advantage at 5 years with mesocolic plane surgery compared with surgery in the muscularis propria plane (HR 0.57 [0.38-0.85], p=0.006) in univariate analysis. However, this association was no longer significant in the multivariate model (HR 0.86 [95% CI 0.56-1.31], p=0.472), but was especially noted in patients with stage III cancers (HR 0.45 [95% CI 0.24-0.85], p=0.014; multivariate analysis). The plane of surgery and amount of mesocolon removed varied between the different sites with better planes in left-sided resections than right-sided ones, which were better than transverse resection (p<0.0001). INTERPRETATION: As previously shown in the rectum, we have now shown there is marked variability in the plane of surgery achieved in colon cancer. Improving the plane of dissection might improve survival, especially in patients with stage III disease. If confirmed by clinical trial data, such as from the ongoing National Cancer Research Institute Fluoropyrimidine, Oxaliplatin and Targeted Receptor pre-Operative Therapy for colon cancer (FOxTROT) trial of neoadjuvant chemotherapy in advanced resectable colon cancer, improvement of the plane of dissection might be a new cost-effective method of decreasing morbidity and mortality in patients with colon cancer.

A patient with a macrodont, transposition and supplemental tooth in the upper anterior segment: a case report.

UNLABELLED: This case report describes the presence of multiple dental anomalies in the upper labial segment of a 7-year-old boy; a macrodont, transposition and supplemental tooth. CLINICAL RELEVANCE: This case highlights the need for careful treatment planning in patients with mutiple dental anomalies.

Exposure to nitrous oxide in a paediatric dental unit.

OBJECTIVE: The aim of this study was to evaluate the 8-h time-weighted average (8-h TWA) exposure to nitrous oxide of dentists working in a paediatric dental unit, and to relate this to various operator, patient and environmental factors. METHODS: This prospective, open-label study monitored nitrous oxide levels using either a personal dosimeter or an electronic sensor worn by the operator. Information was recorded by three dental operators administering nitrous oxide/oxygen for inhalational sedation. Thirty-four paediatric dental patients were treated over a total of 17 treatment sessions. RESULTS: Active scavenging was used for all children; 23 were treated using the Porter-Brown scavenging system and 11 with the Accutron system. Exposure to nitrous oxide expressed as an 8-h TWA ranged from 16 to 374 ppm, with a mean of 151 ppm. The recommended 8-h TWA of 100 ppm was achieved in only 38% of cases. Ambient nitrous oxide levels apparently increased with restorative treatment, poorer behaviour, when the extractor fan was switched off, with patients over 10 years of age and an increased number of sequential patients. CONCLUSIONS: This study found that the recommended 8-h TWA was achieved in only 38% of treatment episodes, despite the use of active scavenging.

Surgery for locally recurrent rectal cancer.

PURPOSE: Resection of locally recurrent rectal cancer after curative resection represents a difficult clinical problem and a surgical challenge. The aim of this study was to assess the outcome of a series of patients who underwent resection of locally recurrent rectal cancer with curative intent. METHODS: A retrospective review was performed of 64 patients who underwent surgical exploration with a view to cure for locally recurrent rectal cancer under the care of one surgeon between April 1997 and April 2004. Details were obtained on the primary tumor and the operation, the indication for investigation of recurrence, preoperative imaging, operative findings, morbidity and mortality, and histopathology. RESULTS: The median time interval between resection of primary tumor and surgery for locally recurrent disease was 31 (interquartile range, 21 to 48) months. Twenty-three patients had central disease, 10 patients had sacral involvement, 21 patients had pelvic sidewall involvement, and 10 patients had both sacral and sidewall involvement. Fifty-seven patients underwent resection of the tumor. Thirty-nine of the 57 patients underwent wide resection (abdominoperineal excision of rectum, anterior resection, or Hartmann's procedure) whereas 18 patients (31.6 percent) required radical resection (pelvic exenteration or sacrectomy). Curative, negative resection margins were obtained in 21 of 57 patients who had tumor excision (36.8 percent). Perioperative mortality was 1.6 percent. Significant postoperative morbidity occurred in 40 percent of patients. CONCLUSIONS: This study has shown that a significant proportion of patients with locally recurrent rectal cancer can undergo resection with negative margins.

Altered intestinal morphology and immunity in patients with acute necrotizing pancreatitis.

PURPOSE/BACKGROUND: Impairment of gut barrier function has been demonstrated in patients with severe acute pancreatitis and may contribute to the development of local and systemic septic complications. The underlying mechanisms, however, remain unclear. Against this background, our aims were to investigate the small intestinal epithelial morphology and mucosal immunity in patients with severe acute pancreatitis. METHODS: Segments of terminal ileum from three patients with severe necrotizing acute pancreatitis who underwent pancreatic debridement and ileocolic resection for doubtful or evident segmental colonic viability were available for the study. Control specimens were available from seven patients who underwent gastric bypass and distal ileal resection for morbid obesity. Sections were cut and stained with hematoxylin and eosin for the measurement of villous height and crypt depth, and with toluidine blue for the determination of mucosal mast cell counts. Only adequately oriented specimens were deemed suitable for computer-aided image analysis. Results were expressed as the villous height/crypt depth ratio (VH/CD) and mucosal mast cell index (ratio of mast cell count/length of muscularis mucosa). RESULTS: Microscopy of the small intestine from controls was normal. The villous height and VH/CD were significantly reduced in patients with acute pancreatitis compared with controls (median, 0.47 mm vs 0.68 mm, and 1.9 vs 2.8, respectively; P < 0.00001). The mast cell index was significantly reduced in patients with acute pancreatitis compared with controls (median, 5.88 cells/mm vs 8.58 cells/mm; P= 0.001). A positive correlation was observed between the mast cell index and the height of the villi ( r= 0.23; P= 0.027). CONCLUSIONS: Patients with necrotizing acute pancreatitis have an altered intestinal morphology and depleted mucosal mast cells. These factors may contribute to the impairment of gut barrier function in patients with severe acute pancreatitis.