JPC SYSTEMIC PATHOLOGY
Signalment (D95-9535A): A horse
HISTORY: This horse had epistaxis; rhinoscopy revealed a mass in the left nostril and, a large reddish brown mass that appeared to compress the nasopharyngeal area was seen in the right nostril.
HISTOPATHOLOGIC DESCRIPTION: Respiratory epithelium and submucosa: The submucosa is expanded and mucosa is elevated by a polypoid mass composed of numerous macrophages and multinucleated giant cells (both foreign-body and Langhan's type), moderate numbers of lymphocytes and plasma cells, admixed with hemorrhage, fibrin, and ectatic lymphatics (edema), and multifocal increased numbers of small to medium caliber vessels (neovascularization). Many giant cells and macrophages contain abundant golden-yellow granular pigment (hemosiderin/hemotoidin) and there are large, extracellular globular aggregates of yellow hematoidin pigment (ceroid sequins). There are multifocal small aggregates of deeply basophilic, finely granular pigment (mineralization). There is a focally extensive area (5 x 0.5 mm) within the submucosa composed of thin trabeculae of woven bone oriented perpendicular to the mucosal surface (periosteal proliferation of a turbinate) surrounded by numerous osteoblasts and separated by loose fibrous connective tissue. Multifocally, the overlying respiratory epithelium is ulcerated or mildly thickened (hyperplasia).
MORPHOLOGIC DIAGNOSIS: Nasal mucosa: Polyp, fibrovascular, with hemorrhage, hemosiderosis, hematoidin (‘ceroid sequins’) and granulomatous inflammation (ethmoid hematoma), breed not specified, equine.
CONDITION: Ethmoid hematoma
SYNONYMS: Progressive hematoma; progressive ethmoid hematoma (PEH); hemorrhagic nasal polyp
- Occurs in horses > 8 years of age; thoroughbreds, Arabians and warmbloods most commonly affected
- Recurrence following surgical excision is common
- Although the pathogenesis of nasal polyps is unknown, they are assumed to represent an aberrant vasoproliferative response to submucosal hemorrhage
- Originate near or within the ethmoid labyrinth or from paranasal sinuses (sphenopalatine, frontal or caudal maxillary)
- Suggested to arise from a protuberant submucosal hematoma produced by hemorrhage from the vascular bed of the ethmoid labyrinth
TYPICAL CLINICAL FINDINGS:
- Slight epistaxis/nasal discharge at the affected nostril for weeks to years before presentation is the most commonly reported clinical sign
- Abnormal inspiratory and expiratory noise at exercise; coughing; episodes of choking; hypersalivation; slight bulging of facial bones over the paranasal sinuses; malodorous breath; head shyness; head shaking
TYPICAL GROSS FINDINGS:
- Usually smooth-surfaced and soft; range in color from off-white to pink, red, brown, green, or purple
- As mass grows, it often protrudes into surrounding paranasal sinuses and may extend rostrally into the nasal cavity towards the nostrils and caudally into the nasopharynx
- May cause distortion and necrosis of turbinates
- Capsule may be ulcerated or inflamed from secondary bacterial infection
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Hemorrhagic stromal tissue with hemosiderin-laden macrophages, multinucleate giant cells, and plasma cells
- Yellow to golden round globules of hematoidin (ceroid sequins)
- Epithelium may be ulcerated with a submucosal capsule of fibrous tissue
- Occasional mineralization of connective tissue
Diseases that can cause blood-stained nasal discharge:
- Guttural pouch mycosis (Aspergillus nidulans)
- In severe cases this can result in thrombosis, aneurysm formation, and rupture of the internal carotid artery
- Tends to be isolated episodes of profuse epistaxis if the first episode is not fatal
- Fungal granulomas
- Nasal amyloidosis
- Neoplasia of paranasal sinuses or nasal passages; endoscopy or biopsy to diagnose
- Paranasal sinusitis
- Facial bone fractures
- Nasal polyps in cats are common in kittens and young adults and commonly arise from the middle ear or auditory tube
- Nasal polyps in other domestic species are uncommon
- Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. Philadelphia, PA: Elsevier; 2016:477.
- Lopez A, Martinson SA. Respiratory system. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Mosby; 2016:495-496.
- Pascoe JR. Ethmoid hematoma. In: Smith BP, ed. Large Animal Internal Medicine. 5th ed. St. Louis, MO: Mosby; 2015:561-562.
- Wilson DW. Tumors of the respiratory tract. In: Meuten DJ, ed. Tumors in Domestic Animals. 5th ed. Ames, IA: Iowa State Press; 2017:474.