The burn comb model revisited.

INTRODUCTION: The burn comb model is a well-established model for studying secondary burn progression. It creates four rectangular burn surfaces intercalated by three unburned zones prone to secondary burn progression. While burn progression is a tri-dimensional phenomenon, of which the vertical extension from the superficial to deeper tissue layer is clinically most relevant, the models initial focus was mainly on the horizontal surface extension within interspaces. The aim of this study is to evaluate the correlation between horizontal surface and vertical depth burn progression. METHODS: 24 large (400-450 g) Wistar male rats underwent standardized burn injuries using a burn comb. Laser Doppler flowmetry to assess perfusion, planimetric evaluation of burn progression within interspaces and histological analyses assessing burn depth were performed before burn induction (baseline; BL) and after 1 h, as well as after 1, 4, and 7 days. Histological burn depth was graded from superficial (1) to the subcutaneous layer (5). Furthermore, final scarring time and contracture rate were also assessed. RESULTS: The burn comb resulted in consistent and uniform superficial burns (mean ± SEM burn depth score: 2 ± 0; hour 1) separated by intact but critically perfused interspaces (63 ± 1% of BL; p < 0.05 vs. BL). Tissue damage significantly progressed to the deep dermis within the first day (burn depth score 4.3 ± 0.2; p < 0.05 vs. hour 1), while significant interspace necrosis at the surface did not develop within this time period (4 ± 3% of interspace necrosis; p n.s vs. hour 1). However, interspace necrosis was observed at day 4 (83 ± 3%; p < 0.05 vs. hour 1) and further progressed until day 7 (94 ± 2%; p < 0.05 vs. hour 1). CONCLUSION: This study shows the limits of the burn comb model originally described with a discrepancy between horizontal surface and vertical depth progression of the burn injury. We herein propose a necessary refinement of this model to adequately evaluate vertical depth progression using a histological score. This revisited approach focusing on assessment of depth progression of the burn will allow a better evaluation of experimental burn treatments in future.

Diagnostic Value of Histological Analysis of Punch Biopsies in Suspected Cutaneous Buruli Ulcer: A Study on 32 Cases of Confirmed Buruli Ulcer in Cameroon.

BACKGROUND: Buruli ulcer (BU) is a cutaneous infectious disease caused by Mycobacterium ulcerans. In this prospective study, we aim to clarify the main histopathological features of cutaneous BU based on 4-mm skin punch biopsies and to evaluate the diagnostic value of this method. METHODS: Between 2011 and 2013, a prospective study was conducted in Cameroon. Dry swabs from ulcerative lesions and fine-needle aspirates of nonulcerative lesions were examined for Ziehl-Neelsen (ZN) staining, followed by PCR targeting IS2404 and culture. Two 4-mm punch biopsies were performed in the center and in the periphery of each lesion. RESULTS: The 364 patients included in the study had 422 lesions (381 were ulcerative and 357 lesions were biopsied). Among the 99 ulcerated lesions with a final diagnosis of BU, histological features for BU were fulfilled in 32 lesions. 32/32 showed subcutaneous necrosis with a neutrophilic inflammatory infiltrate. 26/32 presented alcohol-resistant bacilli confirmed by ZN stain on histology. CONCLUSION: Punch biopsies help in establishing the correct diagnosis of BU and also in the differential diagnosis of chronic ulcers. The main histological feature for BU is diffuse coagulative necrosis of subcutaneous tissue, with acid-fast bacilli detected by ZN stain.

Do 40% of patients resected for barrett esophagus with high-grade dysplasia have unsuspected adenocarcinoma?

Results of studies conducted in the last 2 decades suggest that the detection of high-grade dysplasia in patients with Barrett esophagus is the harbinger of a synchronous adenocarcinoma, which remains undetected even by rigorous biopsy protocols but is discovered during resection of the esophagus. The reported prevalence of synchronous carcinomas ranges from 0% to 75%. Other researchers maintain that appropriate surveillance programs can be used to detect carcinomas at a curable stage and to prevent unnecessary esophagectomies. Both logistical difficulties and potential methodological pitfalls have plagued many studies designed to investigate this issue. A large multicenter study that would stratify participants for hitherto unexplored variables (eg, age, gender, and ethnic background) may be required before the 40% occult cancer prevalence can be either confirmed or refuted. However, the large scale needed for such a study to provide reliable data and new developments in endoscopic imaging (eg, magnification endoscopy and optical coherence tomography) and endoscopic therapy (eg, mucosectomy) are likely to make such a study both ethically unacceptable and logistically and financially unfeasible. Future research should utilize the combination of new endoscopic technologies with the continuing search for validated biomarkers that help predict the biological behavior of Barrett epithelium in individual patients, with a particular focus on the possible development of preneoplastic and neoplastic lesions. Pathologists who chose to shift their focus from the traditional morphological investigation of dysplasia to the search for usable biomarkers can position themselves at the center of innovative research projects that could radically modify the management of patients with Barrett esophagus.