Estudo histopatológico comparativo de linfonodos jugulodigástricos em radioterapia de cabeça e pescoço, no cão.

Introduction: The radiotherapy can be used with efficacy exclusively or like adjuvant in the treatment of patients with cervical nodes clinically positives. The results of treatments are reserved in the most of the cases. objective: To describe the histopathological alterations observed in jugulodigastric lymph nodes of a dog submitted to head and neck irradiation with Cobalt 60 (Co60). method: A dog was submitted to irradiation of the lateral left side of the head and neck, with Cobalt 60 (Co60), with doses of 2 Gy a week, during 2 weeks, totally 4 Gy of radiation. We followed to the exereses of a left jugulodigastric lymph node and of a right jugulodigastric lymph node, with subsequently histopathological analysis. Results: In the right jugulodigastric lymph node was observed the absence of the trabecules thas would be projected from the capsule and the absence of young lymph nodules in the lamina that was involved by a dense young connective tissue. In the left jugulodigastric lymph node we observed dense fibrosis ordenned in the center of the piece, envolved by young dense connective disordered tissue. Conclusion: The effects of the radiotherapy destroy the constitutive cells of the lymph nodes, creating an inflammatory process that destroys these cells that are substituted by cicatricle fibrosis tissue. Then the loss of the function of lymph nodes happens, causing obstruction of the lymphatic drainage and immunosuppression transitory because of the loss of cells of the immune system.