This condition was first described by Cook and Littlewort [1974] as an encapsulated expansile mass growing from the ethmoidal recess. In fact, although the predeliction site remains the ethmoidal region and sphenoplatatine sinus, the condition has subsequently been reported as developing from the mucosa of any of the paranasal sinuses.The typical lesion is that of a haematoma contained within a fibrous capsule and covered by respiratory epithelium. Histologically there is no evidence of neoplasia; the tissue consists of organising haematoma with many multinucleate cells containing haemosiderin. The clinical signs are variable but unilateral [or bilateral if the lesion is bilateral] epistaxis and nasal discharge are common. Secondary sinus empyema can be present if the sinus drainage becomes obstructed. The haemorrhage is usually scanty and originates from an area of ulceration on the mass.The clinical progression is very variable; some horses may have small lesions for years and remain asymptomatic or with only an occasional nasal bleed. In others the lesion is rapidly expansile filling the paranasal sinus, nasal cavity or the nasopharynxand may then cause respiratory obstruction.
展开▼
