Vertebral telangiectatic osteosarcoma in a dog

Telangiectatic osteosarcoma (TOS) affecting the seventh cervical vertebra (C7) was diagnosed in a 4-year-old male dog with signs of locomotor dysfunction. Bone lysis and an extradural-extramedullary mass were observed in radiographs and occipital myelograms. The diagnosis was confirmed by histopathologic and immunohistochemical examination of the mass. The tumor was composed of large blood-filled cavities lined by anaplastic stromal cells (malignant osteoblasts). Around the cavities were characteristic tumor giant cells ("bizarre cells"). Immunohistochemically the tumor cells were positive for proliferating cell nuclear antigen. The lining cells of the cysts were negative for von Willebrand factor. The histologic findings in this case of TOS involving C7 were similar to those seen in other cases of TOS in dogs and in people. Immunohistochemistry was a useful tool for assessing malignancy and for ruling out other differential diagnoses.     

Right ventricular rupture after lateral thoracotomy for removal of rib-associated telangiectatic osteosarcoma in a dog

Objective – To describe a case of a focal right ventricular rupture following removal of a rib-associated telangiectatic osteosarcoma (TOS) in a dog.
Case Summary – A 2-year-old spayed female mixed-breed dog, weighing 20 kg, was presented in compensated hypovolemic shock due to active bleeding into the thoracic cavity. The dog was stabilized with appropriate fluid administration. Subsequent computed tomographic examination revealed a large mineralized mass originating from the body of a rib and displacing the heart. Two days after surgical removal of this mass, focal right ventricular rupture occurred and the dog died. The mass was later identified as a TOS.
New or Unique Information Provided – Although hemothorax secondary to TOS has been described previously, this report describes for the first time, spontaneous focal right ventricular rupture as a rare complication of thoracotomy and rib resection for the removal of a rib-associated, intrathoracic TOS.     

Primary jejunal osteosarcoma associated with a surgical sponge in a dog

Primary jejunal osteosarcoma was diagnosed in association with a surgical sponge in a dog. The tumor was biologically aggressive, resulting in widespread metastasis throughout the abdomen within 2 months of surgical resection. Microscopic examination of the resected osteosarcoma revealed strands of gauze material throughout the tumor mass. It was theorized that the presence of a sponge foreign body may have resulted in malignant transformation of adjacent tissues similar to what has been reported to occur after internal fixation of some long-bone fractures.     

Extraskeletal osteosarcoma associated with retained surgical sponge in a dog.

Retained surgical sponges are usually discovered in the abdominal cavity, sometimes years after the surgical procedure, and the typical reaction is formation of a foreign-body granuloma, often called gossypiboma or textiloma. In this instance, an extraskeletal osteosarcoma, associated with the granulomatous reaction to a retained surgical sponge adjacent to the stifle, was diagnosed in an 11-year-old Labrador Retriever 9 years after repair of a ruptured cranial cruciate ligament. Radiographic detection of linear foreign material in the soft tissue mass was the basis for a diagnosis of gossypiboma. The mass was surgically excised. Histologically, fibers consistent with those of cotton gauze were associated with the granulomatous inflammation and the osteosarcoma. Amputation or radiation therapy was declined; the dog was treated conservatively with doxycycline and deracoxib. Three months after surgical excision, the dog was euthanized because of local recurrence of the mass along with lameness and decreased appetite.     

Renal osteosarcoma in a dog

A seven-and-a-half-year-old dog presented with anorexia, lethargy and haematurla. A 1.8 kg abdominal mass was excised and determined to be a primary renal osteosarcoma. Haematuria was observed five months after surgery and the tumour was radiographically determined to have recurred locally. The dog was euthanased 12 days later due to refractory pain and anorexia. Although osteosarcomas are expected to develop distant metastases, this dog was euthanased due to clinical evidence of local tumour recurrence. Haematuria was an indication both of initial tumour development and later recurrence.     

Meningeal osteosarcoma in a dog

A meningeal osteosarcoma was diagnosed in a dog displaying neurologic signs compatible with a space-occupying cerebellar lesion. Gross lesions, restricted to the brain, consisted of a solitary, compressive mass attached to the dura mater overlying the left cerebellum. The mass was composed of single and multinucleated, atypical polygonal cells that lined or rested within lacuna surrounded by eosinophilic, mineralized matrix. The matrical component stained dark green-yellow to blue with Movat's pentachrome stain, deep blue to red with Heidenhain aniline blue stain, and brown-black with Von Kossa stain. Results of these stains were interpreted as tumor osteoid. Foci of dural mineralization and osseous metaplasia were present at the point of tumor attachment. The microscopic observations were interpreted as an osteosarcoma of extraskeletal origin. To our knowledge, these findings represent the first documented case of a meningeal osteosarcoma in a domestic animal species.     

Intraocular osteosarcoma in a dog

A 10-year-old German shepherd dog was presented with unilateral uveitis and hyphaema. Treatment was unsuccessful and the eye was enucleated. Intraocular osteosarcoma was diagnosed by histological examination.     

High-grade surface osteosarcoma in a dog

A case of a high-grade surface osteosarcoma in the thoracic limb of a dog is reported. Radiographically, there was no bone involvement but there was increased soft tissue opacity. An aggressive osteosarcoma was diagnosed on the basis of early metastatic disease and histopathological examination. Previously reported surface osteosarcomas in the dog have been periosteal and parosteal osteosarcomas which are generally considered to have a low to intermediate biological activity. The tumour described here had radiographical, gross pathological, histopathological and biological features consistent with human high-grade surface osteosarcoma. The characteristics of surface osteosarcomas are briefly reviewed.     

Primary ocular osteosarcoma in a dog

An adult male Rottweiler presented to the veterinary medical teaching hospital at Purdue University with a 1-month history of hyphema. On physical examination conjunctivitis, episcleral hyperemia, corneal edema, hyphema, mild glaucoma and loss of vision were observed in the left eye. No other abnormalities were found. The left globe was surgically removed because of the high likelihood of neoplasia and it was fixed in 10% buffered formalin and submitted for pathology. A histologic diagnosis of primary osteosarcoma of the eye was made. Radiographic evaluation did not reveal any evidence of other tumors or pulmonary metastasis. This is the fourth canine case of primary intraocular osteosarcoma to be documented.     

Primary pulmonary osteosarcoma in a dog

An 11-year-old mixed breed dog was referred because of coughing and painful swelling of the distal extremities which had not resolved with antibiotic treatment. A consolidated left cranial lung lobe and hypertrophic osteopathy were identified by radiographs. A unique feature of this report is the marked, rapid reduction in pain and lameness associated with hypertrophic osteopathy after treatment with corticosteroids. Histological examination of an 8 cm diameter, spherical mass found in the excised cranial lung lobe revealed osteosarcoma. No evidence of local or distant metastases was present. The dog survived one year after diagnosis.     

Primary mesenteric root osteosarcoma in a dog

Abstract: A 10‐year‐old spayed female Boxer‐mix was presented with a history of several weeks of soft stools, straining to defecate, inappetance, and lethargy and several days of hematochezia, melena, and dyschezia. Physical examination findings included mild tachycardia and tense cranial abdomen. CBC results indicated moderate mature neutrophilia. Ultrasonographic examination of the abdomen revealed a large mass with complex echogenicity in the cranial abdomen, likely associated with the intestines. Cytologic examination of a fine‐needle aspirate revealed a population of round, stellate, and spindle‐shaped cells arranged individually and in aggregates with occasional cells embedded in an eosinophilic extracellular matrix. The cytologic interpretation was malignant mesenchymal neoplasm with osteosarcoma being the primary differential. Surgical exploration of the abdomen revealed a 10‐cm‐diameter mass located at the intestinal mesenteric root. The mass occluded blood flow to portions of the gastrointestinal tract. The dog was euthanized due to the nonresectable nature of the tumor. Histopathologic examination revealed an expansile poorly demarcated mesenchymal neoplasm composed predominantly of spindloid and pyriform cells, occasionally embedded in a matrix compatible with osteoid. The diagnosis was extraskeletal osteosarcoma of the intestinal mesenteric root, only rarely reported in dogs.     

Multipotential osteosarcoma with various mesenchymal differentiations in a young dog

Apparently synchronous, aggressive, mixed mesenchymal tumors in the right tibia, right femur, left femur, and rib cage produced multiple microscopic metastases in the lungs and macroscopic metastases in the liver, kidney, and spleen in a 1.5-year-old, neutered male, mixed-breed dog. No primary soft tissue tumor mass was present. Microscopically, the neoplasm exhibited osteosarcomatous, chondrosarcomatous, liposarcomatous, leiomyosarcomatous, fibrosarcomatous, angiosarcomatous, and leukocytic differentiation and was diagnosed as a multipotential osteosarcoma with various mesenchymal differentiation. Immunohistochemically, the neoplasm was cytoplasmically immunoreactive for vimentin, osteonectin, osteocalcin, CD 18, CD 31, desmin, and muscle-specific actin. Oil Red O staining was positive within liposarcomatous areas. Skeletal metastases from a primary bone tumor are exceedingly rare in human and veterinary medicine. However, the history, clinical signs, location, microscopic and immunohistochemical features were similar to those described in aggressive, poorly differentiated osteosarcomas of children. In addition, the wide range of mesenchymal tissue differentiation of this neoplasm was unusual, and to the authors' knowledge, an osteosarcoma with this degree of multiple differentiation has not been previously reported in the dog.     

Extraskeletal osteosarcoma of the liver in a dog

An extraskeletal osteosarcoma of the liver is reported in a 14-year-old male Fox Terrier. Ante- and post-mortem radiographs showed calcified nodules in the liver and non-involvement of the skeletal system. The liver was diffusely involved with greyish, mostly mineralized nodules, and metastatic lesions were seen in the diaphragm, omentum, mesentery, and the sternal lymph nodes. Besides the osteosarcoma, a melanoma with metastasis to the regional lymph node was seen in the left hock region.     

Limb-sparing surgery in a dog with osteosarcoma of the proximal femur

OBJECTIVE: To report successful limb-sparing surgery in a dog with a proximal femoral osteosarcoma (OSA) using a composite allograft-prosthetic technique. STUDY DESIGN: Case report. ANIMAL: Client-owned dog. METHODS: A stage IIB OSA of the proximal aspect of the femur was resected in accordance with oncologic and limb-sparing principles. The osseous defect was reconstructed with a proximal femoral allograft and cemented, long-stemmed femoral prosthesis. Soft tissue reconstruction was achieved by suturing host tendons to their respective allogeneic tendons on the allograft. Coxofemoral joint function was preserved using standard total hip arthroplasty techniques. RESULTS: Limb-sparing surgery of the proximal aspect of the femur using a composite allograft-prosthetic technique resulted in excellent limb function. Postoperative complications included aseptic loosening of the femoral composite graft and allograft nonunion, which required revision, traumatic implant luxation, and local tumor recurrence. Limb function was excellent after surgical stabilization of the allograft nonunion but deteriorated after implant luxation 270 days postlimb-sparing surgery. Pulmonary and skeletal metastases were diagnosed and local tumor recurrence suspected 596 and 650 days postoperatively, respectively. The dog was euthanatized 688 days after limb-sparing surgery as a result of progressive local and metastatic disease. CONCLUSIONS AND CLINICAL RELEVANCE: Limb-sparing surgery for dogs with primary bone tumors of the proximal aspect of the femur is feasible with good functional results.