Injection site sarcomas in cats

Use of Enrofloxacin and Hydrotherapy in the Management of Fibrodysplasia Ossificans Progressiva (FOP) in a Savannah Cat

FOP is a rare genetic condition, described mainly in man and cats, characterized by progressive, painful debilitation and shortened lifespan. A 10-month-old neutered male Savannah cat was referred for progressive gait abnormalities and multifocal firm masses within the soft-tissues that were unresponsive to previous treatment. Diagnosis of FOP was based on histopathological evaluation of intralesional biopsies, which revealed osteo-cartilaginous metaplasia and fibrocellular proliferation with intralesional chondrogenesis and endochondral ossification. The cat was managed with 5 mg/kg BID enrofloxacin and hydrotherapy for 3 years until acute death. During that three-year period, the cat displayed consistent improvement in endurance, quality of life, and range of motion. Postmortem histopathology further confirmed the diagnosis of FOP via identification of intramuscular and intra-fascial ossification with lymphoplasmacytic infiltration, degeneration, and regeneration of adjacent myocytes. To the authors' knowledge, this is the first report of long-term enrofloxacin treatment and hydrotherapy for the management of FOP in a cat, leading to improved mobility and survival time, and the first report of FOP in an exotic breed cat.

First reported case of a histiocytic sarcoma in an Armenian hamster (Cricetulus migratorius)

A 14-month-old male Armenian hamster (Cricetulus migratorius) presented with a spontaneous, subcutaneous, firm mass (4.0 × 2.0 × 1.5 cm) on the ventral neck extending towards the cheek pouch causing multifocal small oral ulcerations. This animal was immunized subcutaneously on the dorsal neck for the development of monoclonal antibodies seven months before presentation. The animal was euthanized and necropsy was performed. Histopathology of the mass showed a well demarcated, multilobulated, unencapsulated, highly cellular, neoplastic mass composed of spindle cells arranged in interlacing streams and bundles, with a moderate amount of fibrovascular stroma. The neoplastic cells exhibited indistinct cell borders and a moderate to large amount of eosinophilic, fibrillar cytoplasm, marked anisocytosis and anisokaryosis, binucleated and multinucleated cells, and high mitotic rate. Based on the histomorphologic features of the mass, and the presence of renal tubular hyaline globules and myeloid hyperplasia in the bone marrow, a diagnosis of histiocytic sarcoma was made. The presumptive diagnosis was confirmed by immunohistochemistry, upon which the neoplastic cells showed strong immunoreactivity for the histiocytic cell markers Iba1 and CD11b. Histiocytic sarcomas have been reported in Syrian (Mesocricetus auratus) and Siberian dwarf (Phodopus sungorus) hamsters but, to our knowledge, the current report represents the first case of histiocytic sarcoma described in an Armenian hamster. It is plausible to consider the animal's experimental immunization history and the development of the histiocytic sarcoma to be related. An association between adjuvanted vaccines and soft-tissue sarcomas has been described in cats and referred to as feline injection-site sarcomas.

Targeting Peritumoral Lesions Identified by Computed Tomography and Magnetic Resonance Imaging in Feline Injection-Site Sarcomas for Microscopic Examination

Peritumoral lesions identified during in vivo imaging of feline injection-site sarcoma (FISS) are frequently interpreted as neoplastic. We recently showed that most peritumoral imaging-identified lesions (PTIILs) in FISS are non-neoplastic. In this article, we describe a protocol to target PTIIL for microscopic examination and report on the protocol's performance. Ten client-owned cats with FISS were prospectively enrolled. A fiducial marker sutured onto the skin, centered on the palpable mass, served as reference point throughout the study. Each FISS and surrounding tissue was imaged in vivo by dual phase computed tomography angiography and multiple magnetic resonance imaging pulse sequences and each PTIIL documented. Subgross measurements obtained during trimming aided localization and identification of PTIIL during microscopy. Histologic findings were categorized by descending clinical relevance: neoplastic, equivocal, non-neoplastic, within normal limits (WNL). Based on in vivo imaging resolution limits, histologic findings were ≥3 mm in at least one dimension and ≥3 mm apart. Surgical margins served as control tissue for PTIILs. Eighty-one of 87 PTIIL were examined histologically; 13 were neoplastic, 16 equivocal, and 28 non-neoplastic; 24 had no identified histologic correlate. Two neoplastic and 10 equivocal findings were located outside of PTIILs but none of them were located in sections of surgical margins. Computation of a simple confusion matrix yielded fair sensitivity (70.4%) and low specificity (59.7%) for prediction of PTIIL by histologic findings. After combining instances of normal microanatomy with non-neoplastic histologic findings, specificity increased (85.1%) and sensitivity decreased (35.8%). The protocol is a blueprint for targeting PTIIL for microscopic examination but may benefit from further refinement.

The potential of the combined use of targeted type I interferon pathway inhibitors and oncolytic viruses to treat sarcomas

Replicating oncolytic viruses (OVs) are appealing, new, FDA-approved, therapeutic options for humans with head and neck cancers and melanomas. These treatments are not yet available for veterinary patients, but recent clinical trials have shown several OVs to be safe in dogs and cats. Specific viruses being used to treat sarcomas in dogs include modified canine adenovirus 2, myxoma virus, vesicular stomatitis virus and reovirus. In cats with vaccine-associated sarcomas, poxviruses have been injected postoperatively and a reduced rate of tumour recurrence was documented. To date, the response rates of canine and feline patients to OV therapy have been variable (as they are in people). Optimal methods of OV administration and dosing schedules continue to be evaluated. One way to improve outcomes of OV therapy in veterinary patients may be to use OVs in combination with other immunomodulatory therapies. This review discusses the potential utility of concurrent therapy with an OV and an inhibitor of the type I interferon pathway.

Curative-intent radical en bloc resection using a minimum of a 3 cm margin in feline injection-site sarcomas: a retrospective analysis of 131 cases

Objectives Owing to its highly infiltrative growth, feline injection-site sarcoma (FISS) carries a significant risk of local tumour recurrence. Parameters of possible prognostic significance (eg, tumour size and location, resection of de novo vs recurrent tumours, and achievement of tumour-free surgical margins) were examined with regard to their influence on recurrence rate (RR), disease-free interval (DFI) and survival time (ST). Methods This was a retrospective analysis of cats with FISSs located on the chest or abdominal wall or the interscapular region treated in a single institution using a standardised radical resection technique with 3 cm lateral margins and full-thickness body wall resection (tumours over chest/abdominal wall) or a minimum of two fascial planes (interscapular tumours). Results Median postoperative DFI and ST of 131 cats with FISSs was 21 and 24 months, respectively. Patients operated on for recurrent tumours were significantly more likely to die from tumour-related reasons compared with patients with de novo tumours ( P <0.001). RR and DFI in the different tumour locations were comparable ( P = 0.544 and P = 0.17, respectively). Local tumour recurrence occurred in 38.1% of the cats. Cats operated on for tumour recurrences had a significantly higher chance of another recurrence (RR 55.5% vs 33.3%; P = 0.005). Completeness of excision was determined by taking tumour bed biopsies. Tumour bed biopsies that did not contain tumour cells were associated with a significantly lower RR compared with those with tumour cells (30.5% vs 76.2%). Conclusions and relevance Depending on prognostic factors such as surgery for primary vs recurrent tumour, tumour-free resection margins and tumour location, the RR in FISS ranges from 33-55%, despite curative intent radical surgery. This study may help in identifying patients at risk for recurrence.

Evaluation of adjuvant chemotherapy in feline injection site-associated sarcoma

ABSTRACT Feline Injection Site-Associated Sarcoma (FISS) is a neoplasm that implies in reduction of quality of life and overall survival in feline patients. A retrospective study of 13 cases of FISS was conducted to evaluate the efficacy of surgical treatment associated to chemotherapy with doxorubicin or carboplatin. Local recurrence occurred in all patients. Patients treated with surgery and chemotherapy presented a longer overall survival and disease-free interval when compared to those that solely received surgical treatment, although no statistical significance was observed (p= 0.3360 and 0.7506, respectively). Surgery remains as the main option for FISS treatment. Further prospective studies with larger samples are warranted to investigate the benefit of chemotherapy for this neoplasm.

Orbital rhabdomyosarcoma and traumatic neuroma following enucleation for a uveal schwannoma in a dog: a case report

A 4‐year‐old, female spayed Siberian husky with history of a uveal schwannoma presented for orbital swelling 9 months after enucleation. A second, malignant tumor developed in the same orbit. Therefore, uveal schwannomas may warrant early surgical intervention in the dog.

Histology and Clinical Outcome of Benign and Malignant Vascular Lesions Primary to Feline Cervical Lymph Nodes

A novel form of primary feline hemangiosarcoma and additional cases of plexiform vascularization in the cervical lymph nodes are reported. Sixteen cases of feline lymphadenopathy attributed to abnormal vascular proliferation were identified and evaluated. Most of these lesions were diagnosed histologically as hemangiosarcoma. However, lesions of plexiform vascularization, with and without areas of putative malignant transformation, were also identified. Mean age of the cats was 11 years (range, 3–16 years) with most being domestic shorthair and medium hair (13). Two domestic long hair and 1 Maine Coon were identified. Excisional nodal biopsy was performed in 15 cases and incisional biopsy in 1 case. Six cats were euthanized due to their disease. Survival times ranged from ≤1 month to ≥30 months. We provide a new clinical differential for cervical lymphadenopathy in cats that is not widely recognized. Proper identification of primary nodal vascular lesions in cats will enable further characterization of clinical features and biologic behavior to determine specific therapy.

Radical excision with five-centimeter margins for treatment of feline injection-site sarcomas: 91 cases (1998-2002)

OBJECTIVE

To evaluate outcomes of radical excision of feline injection-site sarcomas (ISS) via assessment of local recurrence and metastasis rates, survival times, and complications associated with surgery.

DESIGN

Retrospective case series.

ANIMALS

91 cats with ISS.

PROCEDURES

Medical records of cats that had radical excision of ISS without adjunctive treatment were reviewed. Information extracted included sex, type of surgical procedure, histologic tumor grade, tumor diameter, time from tumor detection to definitive surgery, complications associated with surgery, whether tumors recurred locally or metastasized, and survival times. Diagnosis of ISS was histologically confirmed, and additional follow-up was performed.

RESULTS

Overall median survival time was 901 days. Thirteen of 91 (14%) cats had local tumor recurrence; 18 (20%) cats had evidence of metastasis after surgery. Median survival time of cats with and without recurrence was 499 and 1,461 days, respectively. Median survival time of cats with and without metastasis was 388 and 1,528 days, respectively. Tumor recurrence and metastasis were significantly associated with survival time, whereas other examined variables were not. Major complications occurred in 10 cats, including 7 with incisional dehiscence.

CONCLUSIONS AND CLINICAL RELEVANCE

Radical excision of ISS resulted in a metastasis rate similar to rates reported previously; the local recurrence rate appeared to be substantially less than rates reported after less aggressive surgeries, with or without adjuvant treatment. Major complication rates were similar to rates reported previously after aggressive surgical resection of ISS. Radical excision may be a valuable means of attaining an improved outcome in the treatment of feline ISS.

Safety of a non-adjuvanted therapeutic vaccine for the treatment of feline dermatophytosis

The safety of a non-adjuvanted inactivated fungal vaccine for the treatment of dermatophytosis in cats was investigated in two studies: a controlled laboratory study, and a placebo-controlled double-blind field study with a cross-over design in Europe. In the laboratory study, two groups of 10 cats each were administered an intramuscular twofold overdose, followed by five single 1 ml doses, of either vaccine or control product at 14-day intervals. In the field study, cats were treated with three intramuscular injections of 1 ml vaccine administered at 14-day intervals, as recommended by the manufacturer. A total of 89 cats were enrolled in the field study and divided into two groups to receive either vaccine or placebo for the first three treatments, followed by the opposite product for the final three treatments. The cats enrolled in the two studies were 12 weeks of age or older, as recommended by the manufacturer. All the cats were monitored closely for possible injection site reactions, systemic reactions (including changes in rectal body temperature) and adverse events. The results from both studies showed no significant differences between the vaccinated cats and the control or placebo-treated cats with regard to local or systemic reactions. A few mild to moderate local reactions were noted, but these were evenly distributed between the vaccinated and placebo-treated cats and resolved within a few days. No severe or serious adverse events related to the vaccinations were observed.

Orbital extraskeletal osteosarcoma following enucleation in a cat: a case report

OBJECTIVE

We present a unique case of a feline orbital extraskeletal osteosarcoma that developed 5 years post-enucleation.

HISTORY

In 2002, an ophthalmologist enucleated the left eye of a 2-year-old neutered male DSH and submitted it to the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). COPLOW diagnosed the left eye with feline diffuse iris melanoma. In June 2007, the cat presented to another veterinarian for moderate swelling of the enucleation site. Palpation suggested a firm mass along the lateral orbital rim and an exploratory orbitotomy revealed a cyst with a mass adhered to it and the ventrolateral orbital rim. The cyst and mass were excised by the veterinarian and submitted to COPLOW. COPLOW diagnosed the tissue as an orbital conjunctival inclusion cyst and an acquired orbital osteosarcoma.

CONCLUSIONS

Following the enucleation, retained conjunctival epithelium became embedded in the connective tissue of the orbit and caused a cyst to develop. The cyst wall consisted of a myofibroblastic collagen-rich matrix and acted as a nidus of chronic irritation and tumor growth. This orbital osteosarcoma resembles feline vaccine-associated sarcomas (VAS), feline post-traumatic ocular sarcomas, and microchip-associated sarcomas in terms of it histopathology and its hypothesized pathogenesis related to exposure to antigenic material such as implanted epithelium, lens protein, vaccine components, and microchips as foreign bodies.

Temporal changes in characteristics of injection-site sarcomas in cats: 392 cases (1990-2006)

OBJECTIVE

To evaluate changes in characteristics of feline injection-site sarcomas (ISSs) from 1990 through 2006.

DESIGN

Retrospective case series.

ANIMALS

392 cats with a histologic diagnosis of soft tissue sarcoma, osteosarcoma, or chondrosarcoma at potential injection sites.

PROCEDURES

Classification and anatomic location of tumors and signalment of affected cats were compared between ISSs diagnosed before and after publication of the Vaccine Associated Feline Sarcoma Task Force vaccination recommendations in 1996.

RESULTS

From before to after publication of the vaccination recommendations, proportions of ISSs significantly decreased in the interscapular (53.4% to 39.5%) and right and left thoracic (10.2% to 3.6% and 9.1% to 1.3%, respectively) regions. On the other hand, proportions of ISSs significantly increased in the right thoracic limb (1.1% to 9.5%) and the combined regions of the right pelvic limb with right lateral aspect of the abdomen (12.5% to 25.0%) and the left pelvic limb with left lateral aspect of the abdomen (11.4% to 13.8%). Patterns of tumor classification and signalment did not change.

CONCLUSIONS AND CLINICAL RELEVANCE

Despite publication of the vaccination recommendations, a high proportion of tumors still developed in the interscapular region. There was also an increase in lateral abdominal ISSs, which are more difficult to treat and are likely attributable to aberrant placement of injections intended for the pelvic limbs. Veterinarians are complying with vaccination recommendations to some extent, but they need to focus on administering vaccines as distally as possible on a limb to allow for complete surgical margins if amputation of a limb is required.

Spirocercosis-associated esophageal sarcomas in dogs

Seventeen client-owned dogs diagnosed with spirocercosis-associated esophageal sarcomas were retrospectively reviewed. The most common clinical signs noticed were vomiting and/or regurgitation (94%), lethargy and depression (59%), pyrexia and anorexia (41% each). Leukocytosis (82%) and microcytic hypochromic anemia (30%) were the most common hematological abnormalities. Caudal thoracic masses were demonstrated on survey radiographs of 13/15 of the dogs and thoracic spondylitis was detected in 12/15 dogs. Spirocerca lupi eggs were detected in 2/8 patients and worms were demonstrated on 1/11 at necropsy. Ten cases underwent surgical attempt to remove the tumors. In six of them partial esophagectomy (PE) was performed and all of them survived the immediate postoperative hospitalization. Five of the cases that underwent PE also received chemotherapy after surgery (doxorubicin (Adriamycin, Upjohn)) with an average survival time of 267 days. The histopathological results of the esophageal tumors were osteosarcoma (9), fibrosarcoma (5) and undifferentiated sarcoma (1). In areas endemic to spirocercosis, regurgitation or vomiting in dogs and microcytic hypochromic anemia and neutrophilia warrant ruling out esophageal sarcomas. Proper surgical treatment could prolong the dogs' lifespan for months, and improve their quality of life.