Retroperitoneal lymphatic malformation in a dog

Abstract

Background: Lymphatic vascular malformations are rare findings in canine patients with six reports available in veterinary literature. Retroperitoneal cystic lymphatic malformations have not been described previously in canine patients and neither has the use of immunohistochemistry to determine their origin, i.e. vascular versus lymphatic. Case presentation: An 8-year-old neutered female Cocker spaniel was referred for pollakiuria, dysuria and a painful abdomen. Computed tomography scanning of the abdomen showed a fluid filled structure adjacent to the urinary bladder. During surgical exploration, a thin walled cystic structure with sero-haemorrhagic fluid was found, extending from the retroperitoneal space into the abdomen. The mass was excised and submitted for histopathology, revealing a cystic mass lined by a fibrovascular capsule within the retroperitoneal/mesenteric adipose tissue. The inner surface of the cyst was lined by a single layer of bland, flattened spindle cells. Intramural blood vessels were well differentiated, with perivascular haemorrhage. On recurrence 11 months later, the mass was excised for the second time and a PleuralPort (Norfolk Animal products) was placed. Fifteen months after initial presentation, progression occurred with haemorrhagic fluid in the cystic space, pleural-and abdominal cavities and the owners opted for euthanasia. Histopathology and positive immunohistochemistry for lymphatic markers lymphatic vessel endothelial hyaluronic acid receptor-1 (LYVE-1) and prospero homeobox protein-1 (PROX-1) confirmed a lymphatic vascular origin of the cystic structure. Conclusions: To our experience, a definitive diagnosis of retroperitoneal cystic malformation of lymphatic origin could be done only by combining the clinical presentation, advanced imaging, histopathology and LYVE-1 and PROX-1 immunohistochemistry. This is the first report of a vascular malformation in a dog where immunohistochemistry was used to make a final diagnosis. A lymphatic malformation, even if rare, should be added on the list of the differential diagnosis in a patient with a retroperitoneal cystic structure containing serohaemorrhagic fluid. Results of this case report can aid in diagnosis of future cases, however, further studies on therapy and management are needed to provide additional information about optimal treatment of these patients.

Novel treatment of recurrent abdominal lymphatic malformations in a dog

“…Many of these had local recurrence several weeks to months later and were treated with a surgery a second time successfully. 6,7,10 An additional case report described the use of cobalt radiation therapy (48 Gy over 12 fractions) in a 5-year-old spayed female Airedale Terrier with recurrent lymphangioma of the caudal crus of the left hind limb. The dog was disease-free 24 months after treatment.…”

“…In two single reports and a case series describing lymphatic malformations/lymphangiomas in dogs, locations included the caudal inguinal region, retroperitoneum (2), left medial thigh, nasopharynx and left axilla. Many of these had local recurrence several weeks to months later and were treated with a surgery a second time successfully 6,7,10 . An additional case report described the use of cobalt radiation therapy (48 Gy over 12 fractions) in a 5‐year‐old spayed female Airedale Terrier with recurrent lymphangioma of the caudal crus of the left hind limb.…”

“…However, this term is misleading as the abnormality is the result of a disorder of morphogenesis rather than a neoplastic process. 6 In fact, human medicine has attempted to rename lymphangiomas to lymphatic malformations, but both terms are still used in the literature. 1 A review of the veterinary literature revealed only nine reports of confirmed or suspected lymphatic malformation/ lymphangioma in 12 dogs.…”

“…In veterinary medicine, lymphangioma has been specifically used to refer to congenital malformations with a lymphatic origin. However, this term is misleading as the abnormality is the result of a disorder of morphogenesis rather than a neoplastic process 6 . In fact, human medicine has attempted to rename lymphangiomas to lymphatic malformations, but both terms are still used in the literature 1 …”

“…1 A review of the veterinary literature revealed only nine reports of confirmed or suspected lymphatic malformation/ lymphangioma in 12 dogs. [6][7][8][9][10][11][12][13][14] Of these dogs, the lymphatic malformations/lymphangiomas were in the retroperitoneum (2), nasopharynx, axilla, medial aspect of the pelvic limb (3), metacarpal pad, caudal crus, inguinal region and ventral abdomen (2). A case report describing peritoneal lymphatic malformations in a dog, as in this case, could not be found.…”