A 16-year-old female dog, suffering from a massive paraspinal mass on her left lower back for the past 6 months, was presented to the hospital. Upon physical examination, the mass appeared firm and seemed to adhere to the lumbar spine. A fine needle biopsy with cytological analysis revealed a malignant mesenchymal neoplasia suggestive of sarcoma. Her clinical evaluation showed a good general condition except for moderate heart disease. An abdominal ultrasound and a chest X-ray showed no signs of metastases. Initially, she was referred for palliative treatment, as the mass was considered nonresectable due to its size and location. A CT examination with contrast was performed to assess the extent of the mass, as well as its relationship to the surrounding tissues and the lumbar spine.
CT images showed a massive retroperitoneal soft tissue mass, measuring 5.9 x 4.1 x 9.5 cm in size, on the left side of the lumbar spine, extending from the level of the left kidney lower pole to behind the upper iliac crest. The mass showed heterogeneous density without enhancement. It suppressed the paravertebral muscles with well-defined borders and did not infiltrate into the surrounding soft tissues. Signs of osteoarticular degeneration in the spine, pelvis and bilateral hips were seen with no destruction. No metastases were visualized. Based on CT findings, the treatment plan was changed from palliative to surgical. She was referred to cardiology service for treatment, and after being released, underwent surgical intervention with complete removal of the mass. Electrochemotherapy was performed in the surgical bed without intercurrences. The histopathology analysis of the resected mass revealed a moderately differentiated dermal hemangiosarcoma (HSA). Chemotherapy began 20 days after the surgery. In the 6-month follow up, there was neither local recurrence nor metastases found. She recovered well and was disease-free.
Fig. 1: Two transversal images from the native (Fig. 1a) and contrast scan (Fig. 1b), along with two images in dorsal (Fig. 1c) and median planes (Fig.1d), show a massive retroperitoneal soft tissue mass on the left side of the lumbar spine, extending from the level of the left kidney lower pole to behind the upper iliac crest. The mass shows heterogeneous density without enhancement. It suppresses the paravertebral muscles with well-defined border and does not infiltrate into the surrounding soft tissues.
Fig. 2: cVRT images with different presets show the posterior view of the paraspinal mass (Figs. 2a & 2b) and multiple osteoarticular degeneration, without destruction, in the spine, pelvis and bilateral hips (Fig. 2c).
HSA is an aggressive, malignant neoplasm of vascular endothelial origin and can potentially affect any vascularized anatomical site in the body.  The most affected organ is the spleen, followed by the lungs, liver, peritoneum, kidneys, brain, pleura and heart.  HSA is characterized by aggressive biological behavior, is highly invasive and metastatic, and leads to a poor prognosis. It is one of the deadliest forms of cancer encountered in veterinary oncology and dogs are the most frequently affected species.  The diagnosis is made by means of histopathology and immunohistochemistry. A total surgical resection of the primary tumor remains the therapy of choice, aiming at a higher cure rate. Generally, surgery is combined with chemotherapy and adjuvant immunotherapy, considering the rapid development of metastases.  Prior to treatment, a complete clinical workup as well as an imaging evaluation are necessary. Over the past two decades, CT has been recognized as a great technological advancement in veterinary medicine, increasingly performed and gaining more space. Compared to conventional radiography, CT presents superior sensitivity and greater efficiency in the visualization of soft tissues with the ability to determine the origin, extensions, conformations and involvement of the tumor as well as metastases. The images can be reconstructed and viewed in transversal, dorsal and median planes with no overlapping of different anatomical structures. Advanced technology in three-dimensional visualization, such as cinematic volume rendering technique (cVRT), is also available for a lifelike demonstration. All contribute to an optimal therapeutic planning and a positive clinical outcome, bringing greater benefits to the patient.   In this case, the treatment plan was changed from palliative to surgical based upon the CT findings, resulting in an improved quality of life and a greater life expectancy.
16 x 0.7 mm