Neoplasia, Nasal and Paranasal
Basic Information
Epidemiology
Associated Conditions and Disorders
• Secondary paranasal sinusitis is common with primary neoplasia of the sinuses because of disruption of normal sinus drainage mechanisms and the presence of necrotic tissue and secondary bacterial infection.
• Paranasal sinus cysts commonly present with similar clinical signs of nasal discharge and external facial swelling.
Clinical Presentation
History, Chief Complaint
• Most sinonasal tumors are slowly growing with an insidious onset of clinical signs. Horses typically have a history of developing nasal discharge (mucoid to purulent; maybe bloody) that persists and perhaps has a foul odor.
• The presence of an expanding external facial swelling is also a common presenting complaint.
• An increased respiratory noise and reduced nasal airflow may be reported.
• Some horses may be presented for head shaking.
• Clinical signs may advance over weeks to months before veterinary attention is sought.
Etiology and Pathophysiology
• SCC and bone tumors are more common in the maxillary sinus. Glandular epithelial tumors (eg, adenocarcinoma) are more likely to arise from the frontal and ethmoidal sinuses.
• The frontal and ethmoidal sinuses have a greater density of mucosal glands, which may account for the increased incidence of glandular epithelial tumors in these locations compared with other sinus regions.
• Distant metastasis is rare; in addition to locally invasive and destructive growth, carcinomas frequently spread to other sites in the head (nasopharynx, oropharynx, periorbital, cranium, guttural pouch), resulting in diverse clinical signs.
• Osteomas are benign, generally well-circumscribed masses and are not infiltrative.
Diagnosis
Differential Diagnosis
• Paranasal sinus cyst, possibly extending into nasal passage
• Fungal rhinitis or sinusitis
• Nasal epidermal inclusion cyst (atheroma)
• Infection with Halicephalobus gingivalis (a saprophytic nematode)