Diagnostic Features of Feline Restrictive Orbital Myofibroblastic Sarcoma

Abstract

A progressive debilitating disease of the orbit and adjacent connective tissues of cats has historically been called feline orbital pseudotumor. The authors reviewed clinical, histopathologic, and diagnostic imaging features of this disease in 12 cases from the Comparative Ocular Pathology Laboratory of Wisconsin. The cats' ages ranged from 7 to 16 years (mean, 10.8 years). All cats had a history of severely restricted mobility of the globe and eyelids with secondary corneal disease. Eleven cats (92%) had concurrent involvement of the contralateral eye and/or the oral cavity. Diffuse scleral or episcleral thickening was seen with computed tomography in all clinically affected eyes. Histologically, an insidious infiltration of neoplastic spindle cells in the orbit, eyelids, and periorbital skin and soft tissues, with collagen deposition and a few perivascular lymphocytes, led to entrapment and restricted mobility of the eyelids and orbital tissues. The tumor failed to form a discrete mass, and it spread along fascial planes to the contralateral orbit and eyelids and/or the lips and oral cavity. In all tested cases (n ¼ 10), neoplastic cells were immunohistochemically positive for vimentin, S100 protein, and smooth muscle actin. The authors adopted the term feline restrictive orbital myofibroblastic sarcoma to reflect the restricted mobility of the eyelids and globe and the imaging and histologic features of an invasive yet low-grade myofibroblastic sarcoma.

Restrictive orbital myofibroblastic sarcoma in a cat – Cross‐sectional imaging (MRI&CT) appearance, treatment, and outcome

“…No cells were labeled with Melan A or CD18. The pathologic diagnosis was feline restrictive orbital myofibroblastic sarcoma (FROMS) . Within the superficial aspect of the left orbit, an extensive spindle cell‐rich granulation tissue, elements of suture material, lymphoplasmacytic inflammation, and small areas of granulomatous inflammatory infiltrate were noted.…”

Idiopathic sclerosing orbital inflammation mimicking a malignant spindle cell tumor in a dog

“…Descriptions of orbital pseudotumor in the veterinary literature, however, include only one prosimian primate and a lacrimal pseudotumor in a bull terrier 26, 27. Feline lesions originally recorded as orbital pseudotumor have since been reclassified as feline restrictive orbital myofibroblastic sarcoma (FROMS) owing to their highly aggressive nature, resulting in bilateral exenteration and/or euthanasia in all reported cases 1, 3, 28, 29. However, a few early reports in this species did describe a relatively extended survival time alongside immunosuppressive treatment 13, suggesting one or more of the following: (1) that a less aggressive subtype exists, (2) that patient‐derived factors modify disease progression and/or therapeutic response, or (3) that FROMS and feline IOI are two separate disease entities.…”

“…Feline restrictive orbital myofibroblastic sarcoma displays a mixed inflammatory response with perivascular cellular infiltrate and fibrous tissue spreading along fascial planes 1. Mild fibroblastic pleomorphism without mitotic figures and positive immunohistochemistry for S100, smooth muscle actin and vimentin (with or without glial fibrillary acidic protein) are additional characteristic features not seen in the canine mass 1, 28.…”

“…Whilst IOI is rare beyond human medicine, our findings highlight the need to consider this diagnosis in dogs presenting with recalcitrant ophthalmic signs associated with a retrobulbar mass. Given their proximity to the brain, and propensity for local invasion and contralateral emergence, early referral for these lesions is warranted, even though a standard‐of‐care therapy is not clear 1, 28, 29. Advanced imaging instituted promptly may capture early changes in the contralateral orbit (for bilateral presentations) before clinical signs emerge, and immunomodulatory therapy (with or without surgery) may improve patient welfare.…”

High-Grade Myofibroblastic Sarcoma of Inguinal Region in a Dog

“…Of these subtypes, high-grade myofibroblastic sarcoma is characterized by proliferation of elongated spindle-shaped tumor cells with fascicular or herringbone growth patterns that show numerous mitoses and abundant collagen production [22]. In domestic and companion animals, there are several reports of inflammatory myofibroblastic tumors in dogs [2, 13, 17] and domestic animals [19], cardiac myofibroblastic tumor in a dog [14] and low-grade myofibroblastic sarcomas in cats [1]. In addition, we have recently reported a case of low-grade myofibroblastic sarcoma in a dog [28].…”