Canine primary ureteral leiomyosarcoma treated with unilateral left ureteronephrectomy

Abstract

Background: Primary ureteral neoplasms are extremely rare in dogs, and ureteral involvement usually occurs owing to the invasion of renal and bladder tumors.

Case description: This case report describes a 12-year-old intact male mixed-breed dog referred to a private clinic with a six-month history of abdominal distention. A physical examination revealed mild abdominal pain. Hematological tests detected normocytic-normochromic anemia (hematocrit 33.6% [reference interval-RI: 37%-55%], red blood cells 4.93 M/µl [RI: 5.5-8.5 M/µl], and hemoglobin 12.4 g/dl [RI: 12-18.0 g/dl]). The results from the leukogram, thrombogram, renal, and hepatic panels were within the reference intervals for dogs. Abdominal ultrasonography revealed a cavitary mass measuring approximately 12 cm in diameter as the largest tumor in the left abdominal region over the left hepatic lobe or mesenteric site. Chest radiography did not reveal any metastasis. Therefore, the patient underwent exploratory laparotomy, during which the left ureter was found to be affected by a 12-cm mass that adhered to the left kidney. A unilateral left ureteronephrectomy was performed, and histology and immunohistochemistry (IHC) confirmed well-differentiated primary ureteral leiomyosarcoma. The patient survived for 130 days but died of lung metastasis.

Conclusion: Ureteral leiomyosarcoma should be investigated and included in the list of differential diagnoses for primary ureteral neoplasms. Regardless of the therapeutic modality, the prognosis of ureteral leiomyosarcoma may be unfavorable, as shown in this report.

Keywords: Dogs; Leiomyosarcoma; Ureteral neoplasm; Ureteronephrectomy.

Fig. 1.. Exploratory laparotomy in a mixed-breed dog showing a large mass measuring approximately 12 cm in the largest tumor diameter in the left abdominal region over the left hepatic lobe or mesenteric site.

Fig. 2.. Photomicrographs of a canine ureteral leiomyosarcoma hematoxylin and eosin stanning. (A) Lower magnification of neoplastic cells showing a mesenchymal cell proliferation, with areas of necrosis. HE, 10x. (B) Higher magnification of a malignant diffuse mesenchymal neoplastic cell proliferation, arranged in dense bundles, separated by stroma. Cells present a moderate anisocariosis, with evident nucleoli. HE, 40x. (C) Cells presenting eosinophilic cytoplasm, poorly delimited, sometimes vacuolized, round to oval nucleus with loose chromatin and small evident nucleolus. Examination reveals a blood vessel (asterisk) with mesenchymal malignancy and the cells invading the stroma in the direction of the blood vessel (arrow).HE, 40x. (D) Higher magnification of neoplastic cells invading tissue stroma (arrows) in the direction of blood vessels (asterisk) 40x.

Fig. 3.. Photomicrographs of a canine ureteral leiomyosarcoma. (A) Positive staining for GATA3 in normal urothelial mucosa in the ureter, 20x. (B) Staining for UPIII in normal urothelial mucosa in the ureter, 20x. (C) Positive staining for alpha-smooth muscle actin (1A4) in neoplastic cells, 10x. (D) Positive staining for muscle-specific actin, 10x. (E) Positive staining for smooth muscle myosin heavy chain, 40x. (F) Scatted positive staining for desmin, 10x. IHC, Harris hematoxylin counterstaining.

Fig. 4.. Radiographic two-view projections of a canine diagnosed with ureteral well-differentiated leiomyosarcoma. (A) Latero-lateral projection showing diffuse multiple nodules in the lungs. (B) Ventrodorsal projection with diffuse multiple nodules suggestive of pulmonary metastasis.

Fig. 5.. Photomicrographs of a canine ureteral leiomyosarcoma. (A) Positive staining for pancytokeratin (AE1AE3) in normal urothelial mucosa in the ureter with negative staining of mesenchymal cell proliferation below, 10x.