Lymphangioma at the neck of a filly

Abstract

A warmblood filly was born with a 10 x 15 x 15cm fluctuating mass at the ventral aspect of the neck in its upper third. The neonatal foal was in normal health condition, showed normal development and the mass did not appear to be painful or detrimental to the foal, therefore no initial treatment was performed. Because the mass progressively enlarged, the foal was then referred for further diagnostic procedures and treatment at the age of four weeks. The filly presented with an approximately 20 x 20 x 15cm, fluctuating mass ventrally in the upper third of the neck. The mass was covered by normal skin and was still non-painful upon palpation. Clinical examination, ultrasound and positive contrast radiography confirmed the subcutaneous location of the mass and excluded relation to any vital structures such as large vessels or the esophagus. Especially when the foal was active, the mass was quite mobile with marked movement from side-to-side. After exercise the mass appeared to be larger and mild bleeding into the mass was suspected. For this reason and to avoid rupture or trauma to the mass, as well as for cosmetic reasons, surgical resection of the mass was suggested. Surgical excision was performed under general anaesthesia with the foal in dorsal recumbency and the mass resected in toto from its subcutaneous location. Redundant skin was also resected and the wound was closed routinely in a two layer fashion. The mass was submitted for histopathologic examination which showed fibrocollagenous tissue inbedded in the subcutis and with multiple empty cavities that were partly unlined and partly lined with a simple endothelium and forming multiple septae. Mild hyperaemia and vasodilation but no inflammation could be observed. The mass was diagnosed as a lymphangioma. Recovery from surgery and post-operative healing was uneventful and the foal was discharged from the hospital five days after surgical intervention. At 10 weeks after surgery the foal was in good health-condition and the wound was completely healed with a small scar, indicating an excellent cosmetic result.Lymphangiomas are very rare and the authors could only find four cases of equine lymphangiomas in the veterinary literature. For three of these cases a lethal outcome was described because of location, invasivity of the mass or both. Similar to the current case, the only case that survived, also suffered from a ventral cervical lymphangioma. Lymphangiomas consist of proliferating lymphatic vessels within a fibrovascular stroma and they are thought to represent hamartomas, i. e. tumor-like proliferative disease originating from fetal development of the lymphatic system. Therefore, these neoplasms are usually seen in young individuals. Because of their development from the lymphatic system, they are found in locations in which the lymphatic tissues develop. Therefore, the most frequent locations are along the neck, axilla, retroperitoneal tissue, thigh and inguinal region bilaterally. Although an infrequent disease process, practitioners should include lymphangioma in their list of differential diagnoses in cases of congenital swelling in the aforementioned regions. Lymphangiomas at the neck could have a better prognosis than those in other locations.