Chapter 24 Surgery of the Lymphatic System Lymphangiomas are rare, benign neoplasms originating from lymphatic capillaries. They are believed to be developmental anomalies associated with failure of primitive lymphatic sacs to establish venous communication. These endothelial sprouts continue to grow, infiltrate surrounding tissue, cause pressure and subsequent necrosis, and form cystic structures. They typically manifest as large, fluctuant swellings that are noticed incidentally or because of interference with normal structures as a result of expansive growth. They have been identified arising from subcutaneous tissue, the nasopharynx, and the retroperitoneal space of dogs and in the liver and the mediastinum in cats. Affected dogs usually are middle-aged or older; however, lymphangiomas may occur in young dogs. In a recent study of vascular tumors in 420 dogs, only one lymphangioma was observed (Gamlem et al, 2008). Treatment for lymphangioma consists of complete surgical excision or marsupialization. A lymphangiomatous mass arising from the right palatine tonsil was removed without complications or evidence of recurrence in an 8-year-old female dog (Miller et al, 2008). Lymphangiosarcomas (Fig. 24-2) are malignant tumors that arise from lymphatic capillaries. They are locally aggressive, and metastasis to regional lymph nodes, lungs, spleen, kidneys, and bone marrow has been reported. Even without metastasis, the local invasiveness of this tumor often necessitates euthanasia. Surgical resection may be considered; however, cure is unlikely. These tumors have been reported most often in medium- to large-breed dogs. They may occur in young dogs; however, most affected dogs are middle-aged or older. Diagnosis may be made by histopathology, electron microscopy, immunohistochemistry, tissue culture, and/or endothelial expression of glycoconjugates (Williams, 2005). Histologically, lymphangiomas and lymphangiosarcomas are composed of vascular spaces lined by endothelial cells and focal lymphoid aggregates divided by connective tissue stroma. Unlike hemangiomas, the cystic spaces of these tumors are not filled with blood. Perioperative antibiotics are seldom indicated in animals undergoing lymph node biopsy or removal. Incisional (wedge) biopsy of lymph nodes is indicated when lymphadenectomy may be difficult because of a node’s size or location (e.g., nodes that are located close to major vessels or nerves). Use a No. 15 scalpel blade to remove a wedge-shaped section of the parenchyma (Fig. 24-4, A), and place the sample in a buffered formalin solution. To provide hemostasis, place a horizontal mattress suture of absorbable suture material (e.g., 3-0 chromic catgut) to close the incision (Fig. 24-4, B). Gamlem, H, Nordstoga, K, Arnesen, K. Canine vascular neoplasia—a population-based clinicopathologic study of 439 tumours and tumour-like lesions in 420 dogs. APMIS Suppl. 2008;125:41. Miller, AD, Alcaraz, A, McDonough, SP. Tonsillar lymphangiomatous polyp in a dog. J Comp Pathol. 2008;138:215. Nyman, HT, O’Brien, RT. The sonographic evaluation of lymph nodes. Clin Tech Small Animal Pract. 2007;22:128. Williams, JH. Lymphangiosarcoma of dogs: a review. J S Afr Vet Assoc. 2005;76:127. Specific Diseases Make a 5-cm skin incision over the mid-dorsomedial metatarsal region. Use sharp and blunt dissection until a blue-stained, superficial metatarsal lymphatic vessel is identified (Fig. 24-7). Meticulously dissect the lymphatic free from surrounding tissue with fine, blunt dissection probes, and cannulate the lymphatic using a lymph duct cannulator or a 27 or 30 gauge over-the-needle catheter. Inject a small amount of sterile saline into the catheter or cannulator to verify patency. Then manually infuse an aqueous-based radiographic contrast agent into the lymphatic vessel. Take radiographs immediately after the injection (Fig. 24-8); additional radiographs may be taken, depending on the rate of lymphatic transport of the contrast agent, which varies from patient to patient. Upon completion of the lymphangiogram, withdraw the cannulator, ligate the lymphatic vessel, and close the incision in a routine fashion.
Surgery of the Hemolymphatic System
General Principles and Techniques
Preoperative Management
Antibiotics
Surgical Technique
Incisional Biopsy
References
Lymphedema
Surgical Technique
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Surgery of the Hemolymphatic System
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