Retrobulbar Rhabdomyosarcoma in a Hovawart

Abstract

Neaas A. , P. Rau‰er , F. Tich , P. Kohout , H. Kecova : Retrobulbar Rhabdomyosarcoma in a Hovawart. Acta Vet. Brno 2003, 72: 399-404. This clinical case study describes a three-year-old female Hovawart dog presented due to a unilateral exophtalmos and diagnosed with a retrobulbar tumour arising from m. rectus ventralis using ultrasound and computer tomography. The tumour was cytologically classified to be of a malignant mesenchymal kind. Modification of lateral orbitotomy with canthotomy was performed and the circumscribed tumour resected in its entirety. After healing, the eye was like the healthy contralateral one. Three months later, however, there was a relapse of the same extent and the patient was euthanised on the owner s request. Rhabdomyosarcoma was confirmed by repeated histological examinations. Tumour, dog, orbitotomy Retrobulbar processes belong to relatively frequent ophthalmological problems of dogs and cats. Apart from inflammatory lesions (abscesses, cellulitis), there are frequently processes of neoplastic origin such as primary or metastatic tumours (Spiess and Wall inHakanson 1999). Kern (1985) mentioned up to 74% of retrobulbar tumours to be of metastatic origin. Cases of retrobulbar tumours are very often malignant. Manson et al. (2001), Kern (1985), and Hendrix and Gelat t (2000) report 42%, 91%, and even up to 95% of malignant tumours, respectively. A total of 21 different retrobulbar neoplasia was described with osteosarcomas, fibrosarcomas and nasal adenocarcinomas (cf. Table) being the most frequent ones. There is one reported case of a retrobulbar rhabdomyosarcoma (Hendrix and Gelat t 2000). No age and breed predisposition of the occurrence of retrobulbar tumours was found (Attal i-Soussay et al. 2001). The mean age, however, is relatively high; i.e., 8.4 and 10.7 years reported by Hendrix and Gelat t (2000) and Attal iSoussay et al. (2001), respectively. Kern (1985) mentions purebred dogs, mostly females of middle age, to be typically affected. Prognosis of cases of retrobulbar neoplasia is generally poor with low survival of patients. Attal i-Soussay et al. (2001) mention that dogs survive for up to 10 months. According to Hendrix and Gelat t (2000) 86% and 19% of dogs live longer than 6 and 12 months, respectively. Radical treatment accompanied by a partial or total orbitectomy decreases the relapse of tumours to 36.7%. More than 70% of patients then survive for a period longer than one year (O Brien et al. 1996). According to At ta l i -Soussay et al. (2001) clinical signs often encountered include exophthalmos (84%), conjunctival hyperaemia (40%), third eyelid prolapse (28%), exposure keratitis (20%) and anomalies of the fundus (20%). Barnet and Grimmes (1972) mention the occurrence of retinal detachment. When the tumour affects the nerve tissue, there may be progressive neurological signs (Andrew 1999). Radiographs often show osteolysis (Mason et al. 2001). Retrobulbar tumours may form metastases, for ACTA VET. BRNO 2003, 72: 399–404 Address for correspondence: Doc. MVDr. Alois Neaas, Ph.D Department of Surgery and Orthopaedics University of Veterinary and Pharmaceutical Sciences Palackeho 1-3, 612 42 Brno, Czech Republic Phone: +420 602 742 484 Fax: +420 541 562 344 E-mail: necas@eurosat.cz http://www.vfu.cz/acta-vet/actavet.htm example, to the lung tissue with subsequent relevant clinical problems (Mart in et al. 2000). Resection of tumours is the treatment of choice. There is a better prognosis when the resection is accompanied by a partial or total orbitectomy (O Brien et al. 1996). For the proper resection of retrobulbar tumours a lateral (Spiess and Wall in-Hakanson 1999) or modified orbitotomy (Gilger et al. 1994) is often necessary.