Iliac Lymphadenectomy following Intrauterine Mapping in a Female Dog with Breast Neoplasm

Background: The lymphatic system plays an important role in the local control of neoplasms as well as in the transportation of tumor cells, which represents the most common pathway of metastasis. From the tumorigenesis, there is a remarkable enlargement of the tumor drainage network towards the regional and target lymph nodes. Since the mammary lymphatic system of animals with neoplasms as well as the demarcation of the pelvic and abdominal caudal chain are poorly studied, the aim of the present study is to report a case of iliac lymphadenectomy after intrauterine lymphatic dyeing in a dog with breast neoplasm, which allowed the identification of metastasis in the medial iliac lymph node.Case: A 7-year-old, 13.4 kg, non neutered, mixed breed, female dog was diagnosed with ulcerative neoplasm in the left caudal abdominal breast, which presented evolution of approximately 90 days, presenting ulceration for 10 days, according to the tutor. After a clinical evaluation, thoracic radiography and abdominal ultrasonography were requested, whichdid not present metastasis suggestive images. Therefore, left unilateral total mastectomy was indicated. Retro-umbilical celiotomy was performed for the administration of 0.5 mL of 1% intrauterine methylene blue (body of the uterus), which allowed lymphatic mapping and medial iliac lymphadenectomy. Subsequently, ovariohysterectomy was performed andafter celiorrhaphy, axillary lymphadenectomy was performed, followed by left unilateral mastectomy and concomitant removal of the superficial inguinal lymph node. The patient had a prompt recovery and was discharged from hospital in six hours postoperatively. The excised material was referred for histopathological examination, which revealed the presence of metastasis of simple tubulopapillary carcinoma of the mammary gland in the left medial and superficial inguinal lymph nodes, while the axillary lymph node had no metastases. At the end of 10 days, the patient was clinically stable, with good healing of the surgical wound. After a 120-day postoperative period, the patient had a good clinical status, with no respiratory alterations, and there was no evidence of metastasis on the chest X-ray as well as abdominal ultrasound.Discussion: Considering the great occurrence of breast neoplasms, it is important to develop studies on new approaches in the therapeutic management of this condition and sharing of reports as described. The objective of the lymphadenectomy was to evaluate the possible involvement of regional lymph nodes, since, according to the condition of the lymph nodes in the histopathological examination, it appears as an important prognostic factor, seeing that the survival time is less thantwo years for 85.7% in dogs with regional lymph node metastases. In animals, there are no studies based on the therapeutic alternative of lymphadenectomy, which is believed to be palliative in the reported patient, due to the fact that it is a tubulopapillary carcinoma with different foci of lymph node metastases. Otherwise, lymphadenectomy enabled a better definition of the prognosis and proved to be an important tool for staging. The use of methylene blue was chosen because it was reportedly used in dogs, with excellent results in sentinel lymph nodes mapping, and due to its ease of obtaining and low cost of application. It is concluded that in canines with breast neoplasms, it is important to perform lymphatic mapping to identify possible metastases in cellular tissues and to delimit regional lymph vessels and lymph nodes, thus facilitating the surgical removal of these structures with safety margins. In addition, it is important to perform lymphadenectomy even to lymph nodes that are not infarcted or present macroscopic changes, given that in this case, it already existed metastasis, even in a lymph node of 4 mm.Keywords: metastasis, sentinel lymph node, lymphatic mapping, mastectomy, canine