Three cases of osteoma and an osseous fibroma of the paranasal sinuses of horses in South Africa : clinical communication

I Cilliers,A Carstens,N.M Duncan,J Williams

doi:10.4102/jsava.v79i4.271

Abstract

Four horses were presented to the Onderstepoort Veterinary Academic Hospital with histories of facial asymmetry, nasal discharge or obstruction of normal nasal passage airflow. Radiographic examination of the maxillary sinuses of 2 cases revealed well circumscribed, unilateral, mineralised masses; the other 2 cases showed less mineralisation. The masses were accessed for further investigation by surgically created frontonasal bone flaps or trephination of the maxillary sinuses. Diagnosis of osteoma was confirmed histopathologically in 3 of the cases and of ossifying fibroma in the 4th. Two horses were euthanased directly after surgical intervention due to poor prognosis. Osteomas are by nature expansile tumours and follow the complex communication of the sinuses, and therefore are not all amenable to surgical removal. Osseous fibromas are large, solitary, expansile lesions that are rare in all species but reported most frequently in horses. They have an apparent predilection for the rostral mandible of the horse.

Highlights

Neoplasia of the paranasal sinuses in horses is uncommon[4,26,28]
Clinical signs of most paranasal sinus neoplasms are generally related to their size, location and pattern of growth
Diagnosis and extent of masses are usually established on interpretation of radiographs, excisional biopsy, histopathology and aDepartment of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa. bDepartment of Pathology, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa

Summary

INTRODUCTION

Neoplasia of the paranasal sinuses in horses is uncommon[4,26,28]. Tumours reported to develop within the sinuses include squamous cell carcinoma, adenocarcinoma, fibrosarcoma, haemangiosarcoma, osteoma, ossifying fibroma and ameloblastic odontoma[6]. Six weeks post-surgery follow-up radiographs revealed no mass in the right maxillary sinus, which was gas-filled, with increased soft tissue opacity in the rostro-ventral region. Case 3 A 14-year-old Historical Boerperd mare with suspected unilateral squamous cell carcinoma of the right 3rd eyelid and possible metastasis to the caudal maxillary sinus region was referred to OVAH for further diagnostics and therapy. Radiographs of the paranasal sinuses including oblique views of the orbits revealed an oval soft tissue opacity (7 × 9 cm) in the ventro-medial region of the right maxillary sinus. Radiographic examination of the paranasal sinuses using routine views including views of the pharyngeal region revealed a 14 × 15 × 8 cm soft tissue opacity within the right nasal passage area extending from the right ethmoid area and causing marked left displacement of the nasal septum and obliteration of the right common nasal meatus (Figs 7a and 7b). Bone and soft tissue 3-D reconstructions of the affected area were made showing a non-homogenous soft tissue density (Hounsfield units of 47–79) within the right maxillary sinus extending into the frontal sinus and the right ventral conchal sinus causing various degrees of bony destruction of the frontal bone, cribiform plate and hard palate and displacing and exerting pressure on maxillary premolars (Fig. 10 a,b,c)

Findings

DISCUSSION

CONCLUSION