Restrictive orbital myofibroblastic sarcoma in a cat--cross-sectional imaging (MRI & CT) appearance, treatment, and outcome.

A 16-year-old spayed female cat was evaluated for lagophthalmos and chronic exposure keratitis in both eyes. Ophthalmic examination revealed upper and lower eyelid entropion of the left eye (OS) and markedly decreased retropulsion, restricted eye movement, marked episcleral congestion, and severe keratitis of both eyes (OU). Magnetic resonance imaging of both orbits revealed extensive, irregular, contrast-enhancing tissue without evidence of osteolysis considered compatible with diffuse inflammatory tissue. Feline herpesvirus DNA was not detected in conjunctival samples. Partial temporary tarsorrhaphies were placed OU, and the cat was treated with topically administered erythromycin ointment OU, orally administered famciclovir and prednisolone, and sublingually administered buprenorphine. Little improvement was noted after 2 weeks. Six weeks after initial presentation, a left exenteration was performed and histopathology was consistent with idiopathic sclerosing orbital pseudotumor (ISOP). Ten weeks after initial presentation, the patient represented for weight loss and jaw pain. Computed tomography demonstrated disease progression in the right orbit and the patient was euthanized. Histopathology of the decalcified skull revealed an aggressive and highly infiltrative mass involving the right orbit with extension to the maxilla, hard palate, nasal cavity and gingiva most consistent with feline restrictive orbital myofibroblastic sarcoma (FROMS). Clinical data from this patient support the reclassification of ISOP as FROMS. MRI and CT may provide supportive evidence for FROMS, but histopathology is necessary for definitive diagnosis. Aggressive and early surgical treatment, including bilateral exenteration, with adjunctive radiotherapy and/or chemotherapy should be considered for patients with FROMS.

The effect of size on the acoustic response of polymer-shelled contrast agents.

In this technical note, we study three polymer-shelled microbubble contrast agents manufactured by POINT Biomedical Corporation that have identical shell composition and mean volumetric diameters of 0.74 microm, 0.91 microm and 1.33 microm. We investigate the effect of agent size on the amplitude, frequency and probability of acoustic echoes received in response to five-cycle, 2.25-MHz pulses of varying pressure. We find that the amplitude and frequency response from the three agents is not significantly different. However, significant differences among the agents do exist in the probability of response to acoustic interrogation: at a pressure of 1.06 MPa, an echo from the 1.33 microm agent is 5 times as likely as an echo from the 0.91 microm agent and 18 times as likely as an echo from the 0.74 microm agent. We hypothesize that there exists an effective pressure-dependent threshold diameter above which single polymer-shelled agents respond to acoustic interrogation.

Use of ethylene-vinyl alcohol copolymer as a liquid embolic agent to treat a peripheral arteriovenous malformation in a dog.

CASE DESCRIPTION: An 11-year-old castrated male Tibetan Mastiff was evaluated because of a visibly enlarged blood vessel and progressively worsening swelling of the right hind limb. CLINICAL FINDINGS: On physical examination, the right hind limb was markedly larger than the left hind limb and the dog was minimally weight bearing on the affected limb. A bruit was auscultated over the affected region. Ultrasonography of the tarsal region of the right hind limb revealed an artery with turbulent flow that communicated with venous drainage. A CT scan confirmed the presence of an arteriovenous malformation (AVM). TREATMENT AND OUTCOME: Embolization of the AVM with a liquid embolic agent (ethylene-vinyl alcohol copolymer dissolved in dimethyl sulfoxide) was elected. An arteriogram was performed prior to treatment and delineated the vessels that were targeted for embolization. The embolic agent was infused into the AVM, and a postinjection arteriogram confirmed complete occlusion of the AVM nidus and normal arterial flow to the paw with subsequent normal venous drainage. The circumference of the abnormal paw was 51 cm before the procedure and 22.9 cm at 4 weeks after the procedure. Additionally, the gait of the dog dramatically improved. No complications associated with the procedure developed. CLINICAL RELEVANCE: Peripheral AVMs in dogs are uncommon, and described treatment options are limited and generally associated with serious morbidity. A liquid embolic agent, ethylene-vinyl alcohol copolymer dissolved in dimethyl sulfoxide, was successfully administered in this case, and no morbidity was observed secondary to the procedure. Clinical success was characterized by substantial improvement in limb swelling and marked improvement in the gait of the dog.