Modelo experimental de pesquisa do linfonodo sentinela no canal anal de cadela utilizando-se tecnécio e azul de metileno

Abstract

The benefits of sentinel node identification in the treatment of cancer in various organs and locations are already well defined, but there is a lack of studies in relation to the anal canal cancer, especially in the absence of experimental models for this purpose. In this study we proposed a model for sentinel lymph node in the anal canal in dogs. We selected 13 mongrel dogs of the species Canis familiaris, females, with approximate weight of 10,9kg and age ranging from 12 to 24 months from the Zoonosis Control Center of the city of Fortaleza; divided into two groups (I and II) in accordance with the local injection of tracers in the anal canal. After general anesthesia, the group I bitches received the injection of 0.5 ml of 99m and 5 ml of methylene blue 1% in previous anal canal region and the dogs in group II received injection of the markers in the posterior region of the anal canal. 30 minutes after injection of the radiopharmaceutical, the inguinal regions were dissected in search of lymph nodes labeled with the vital dye or tracer through the radioactivity uptake by lymph node Gamma-Probe device. Later, the animal laparotomy was performed in search of lymph nodes marked in iliac and pararretais chains. All marked lymph nodes were removed and sent for histopathologic analysis. In total 34 lymph nodes were scored in both groups. The detection method with methylene blue 1% blushed 13.6 times more lymph nodes in the group I and 15.8 in group II, with low agreement by Kappa coefficient. The ROC curve comparing the two methods showed higher specificity Radiocolloid. Both methods found more lymph nodes in the right iliac chain both in group I and group II. Group II showed greater marking unilateral nodes by vital dye method with significance by one-tailed Fisher's exact test (p = 0.043), but the technetium not tended to show significant differences between the marking of unilateral or bilateral lymph nodes. Only one node, marked only with blue, was not confirmed as lymphoid tissue in histopathology. It is concluded that the sentinel lymph node detection method of anal canal in the bitch by methylene blue and technetium is feasible and has a high degree of accuracy.