Synovial sarcoma in a dog.

A 6.5-year-old, female Saint Bernard had a slowly growing tumor of the right tibiotarsal joint. Radiographically, bone surrounding the tumor was not involved. Subtotal surgical resection was undertaken. The tumor was classified histologically as a synovioma. Within 6 months, the tumor recurred locally and invaded the soft tissue proximal to the tibiotarsal joint. Eighteen months after initial examination, there was widespread right tibial invasion and pulmonary metastasis. The dog was euthanatized. The final histopathologic diagnosis was synovial sarcoma.     

Synovial sarcoma of the tendon and tendon sheath in a dog

A 19.5-year-old male mongrel dog developed a progressive lameness and swelling around the right carpus. A tumor (6 x 3 x 3 cm) was found in the caudal of distal antebrachium of the right forelimb, including tendons of the superficial digital flexor muscle and deep digital flexor muscle. No joint destruction was observed. The tumor consisted of round and spindle cells arranged in a compact sheet. There were occasional slit-like spaces or lumina, and areas rich in collagen fibers giving an appearance of tendon tissues. Neoplastic cells gave a positive immunoreaction to vimentin, but negative reactions to antibodies against S-100 protein, cytokeratin and myoglobin. Based on these findings, this tumor was diagnosed as a synovial sarcoma generating from the tendon and tendon sheath, which is very uncommon in dogs.     

Synovial sarcoma in an Ayrshire heifer

An 8-month-old Ayrshire heifer had a rapidly growing mass in the axillary region of the left thoracic limb. The mass surrounded the distal humerus and entrapped nerves of the brachial plexus, causing an abnormal gait. Histologically, the mass was composed of clusters and cords of round to polygonal cells with scattered, spindle-shaped cells. The neoplastic cells stained positively for vimentin and cytokeratin. No staining was found with S-100 protein, kappa and lambda light chains, or T-cell markers by immunohistochemistry. On electron microscopic evaluation, the cytoplasm of the neoplastic cells contained few organelles, principally rough and smooth endoplasmic reticulum and mitochondria. This synovial sarcoma has histologic and ultrastructural features characteristic of the poorly differentiated subtype of synovial sarcoma in the human classification system.     

Synovial sarcoma in the dog–a review

A series of eight cases of synovial sarcoma in the dog is presented together with a literature review of previously reported cases. It is an uncommon tumour occuring mainly around joints and affects more males than females. It occurs most frequently in medium to large dogs of middle age. Clinical signs may develop over a long period of time and the tumour is locally invasive with an unpredictable capacity to metatasise. Radiographically it appears as a soft tissue mass which invades bone. Histological diagnosis may be difficult because of the heterogenicity of the tumour and suitable biopsy techniques are discussed. On present evidence amputation appears to be the most effective form of treatment in the dog.     

Synovial hemangioma in the stifle joint of a dog

Synovial hemangioma was diagnosed in an 8-year-old castrated male Belgian Sheepdog with lameness of 3 months' duration. Pain, soft-tissue swelling, and hemarthrosis were localized to the left stifle joint. Projections of synovial membrane with reddish-purple nodules, excised via arthrotomy, were composed histologically of variably sized vascular channels that were lined by well-differentiated endothelial cells and separated by fibrous septa. Distension of some channels resulted in endothelial disruption, thrombosis, hemorrhage, necrosis, and focal spindle-cell proliferation. The limb was amputated to remove remaining neoplastic tissue. The hemangioma extended focally into the joint capsule and popliteal soft tissue but did not invade skeletal muscle or bone. The dog was free of detectable neoplasia 6 months after amputation. Synovial hemangioma is a rare benign vascular proliferation in people, most commonly in the knee, and should be included in the differential diagnosis for canine synovial tumors.     

Synovial T-cell lymphoma of the stifle in a dog

A 6-year-old, 43-kg, spayed female rottweiler was presented for a 1-month history of progressive, left hind-limb lameness. Upon physical examination, a cranial drawer sign and joint distention were present in the left stifle. Radiographically, the stifle had evidence of effusion, remodeling of the patella, and an enlarged popliteal lymph node. Marked synovial thickening and an intact cranial cruciate ligament were noted during surgery. Despite finding a nonspecific, mixed inflammatory response on joint fluid cytopathology, histopathology demonstrated T-cell lymphoma of the synovium. Lameness may be the sole presenting clinical sign in canine lymphoma.     

Ureteral sarcoma in a dog

A ureteral sarcoma was diagnosed in a nine-year-old Weimaraner dog with gross haematuria, severe unilateral hydronephrosis, and hydroureter. Treatment consisted of unilateral nephrectomy and ureterectomy. This case was compared with 14 other ureteral tumours reported in the veterinary literature. Only three previous reports concerned a malignant ureteral tumour. Urinary tract neoplasms mainly involve the bladder and the kidney, and more rarely the urethra. The purpose of this paper is to report a rare case of malignant ureteral tumour in a dog.     

Multiple skeletal metastases of osteogenic sarcoma in a dog.

A 9-year-old male German Shepherd Dog with osteogenic sarcoma involving the right humerus was treated by scapulohumeral disarticulation and adjuvant chemotherapy. Doxorubicin was used, at a dosage of 30 mg/m2 of body surface. Chemotherapy was unsuccessful, and 4 months after surgery, the dog developed multiple metastases of osteogenic sarcoma in the appendicular skeleton, a metastatic pattern rarely observed with primary bone tumors.     

Spindle cell sarcoma in the kidney of a dog

A spindle cell sarcoma involving the left kidney was diagnosed in a 14-year-old male Basenji. Radiography and ultrasonography were used to define the extent and location of the mass. Metastatic disease was not detected. An 8 x 5-cm mass, involving the left kidney, was resected by performing nephroureterectomy. Signs of metastasis were not detected at 3 and 6 months after surgery. Shortly after the 6-month examination, the dog was euthanatized because of perceived signs of pain attributable to cervical disk disease. Postmortem examination was not performed. Histologic examination consisted of use of hematoxylin and eosin, Masson trichrome, and van Gieson stains, and 4 immunoperoxidase techniques. On the basis of the histologic findings, the final diagnosis was spindle cell sarcoma, with the 2 most likely possibilities being leiomyosarcoma and fibrosarcoma.     

Metastatic transmissible venereal sarcoma in a dog

An adult male dog with large penile sheath and serosanguineous exudate from the preputial orifice and a cutaneous fistula in the right inguinal area was examined. Necropsy revealed tumor masses on the penis and prepuce, in superficial inguinal and external iliac lymph nodes, and in the liver. Histopathologic diagnosis of the tumor was confirmed by transplantation studies.     

Ureteral spindle cell sarcoma in a dog

A five-year-old, female spayed Labrador retriever was presented for further investigation of an intra-abdominal mass. Abdominal exploration showed a large mass arising from the right ureter and a ureteronephrectomy was performed. Histopathology of the ureteral mass was consistent with a spindle cell sarcoma. The patient recovered well, but five months later was diagnosed with another tumour, this time in her left abdominal wall. The owners decided not to pursue further treatment and euthanasia was performed a month later.     

Chemotherapy of synovial cell sarcoma in a dog

A synovial cell sarcoma of the tarsus in a 6-year-old dog was treated with doxorubicin HCl and cyclophosphamide. The tumor regressed after treatment. There was no recurrence 3 years after initiation of treatment. Previously, synovial cell sarcoma has not been reported to be responsive to chemotherapeutic agents, and the treatment of choice has been amputation.     

Paraneoplastic pemphigus in a dog with splenic sarcoma

Paraneoplastic pemphigus (PNP) is an autoimmune blistering skin disease of humans that consists of characteristic skin lesions associated with concurrent neoplasia. In this study we provide histologic and serologic evidence to support a diagnosis of PNP in a dog with splenic sarcoma. Skin lesions consisted of widespread erosions involving haired skin, mucocutaneous junctions, and oral mucosa. Microscopic examination of skin and mucosae revealed lesions consistent with both pemphigus vulgaris and erythema multiforme. Immunoprecipitation confirmed that circulating IgG autoantibodies from this patient recognized five distinct antigens, presumed to represent epidermal plakins. Clinical, histopathologic, and immunologic findings in this patient were similar to those observed in human patients with PNP. The splenic neoplasia in this dog was diagnosed as a phenotypically variable spindle cell sarcoma. To date, only one other dog has been reported with PNP. This is the second reported case of canine PNP and the first patient in whom skin lesions were identified in association with splenic neoplasia.     

High-grade myofibroblastic sarcoma of inguinal region in a dog

A subcutaneous tumor in the left inguinal region was present in an 11-year-old female bloodhound. Histopathologically, the tumor showed invasive growth and extensive necroses, and it was composed of spindle-shaped, elongated, and stellate neoplastic cells accompanied by occasional giant cells arranged in fascicular, herringbone, or irregular storiform patterns with abundant production of collagen fibers. The cytoplasm of most tumor cells was positive for vimentin, alpha-smooth muscle actin, and calponin, but was negative for desmin, smoothelin, and S-100. Furthermore, most of the tumor cells were negative for Iba1 while some tumor cells were weakly positive. Thus, this tumor was diagnosed as a high-grade myofibroblastic sarcoma according to the diagnostic criteria for human myofibroblastic sarcomas.