DEFINITION/OVERVIEW
- Cats: often confusing term for three distinct syndromes—eosinophilic plaque, eosinophilic granuloma, and indolent ulcer.
- Grouped primarily according to their clinical similarities, their frequent concurrent (and recurrent) development, and their positive response to corticosteroids
- Oral lesions seen most commonly in indolent ulcers and eosinophilic granulomas
- Grouped primarily according to their clinical similarities, their frequent concurrent (and recurrent) development, and their positive response to corticosteroids
- Dogs: eosinophilic granulomas in dogs (EGD) rare
- Not part of a disease complex
- Specific differences from cats are listed separately
- Not part of a disease complex
ETIOLOGY/PATHOPHYSIOLOGY
- Eosinophil: major infiltrative cell for eosinophilic granuloma, eosinophilic plaque, and allergic miliary dermatitis, but not indolent ulcer; leukocyte located in greatest numbers in epithelial tissues; most often associated with allergic or parasitic conditions, but has a more general role in the inflammatory reaction
- Genetic: several reports of related affected individuals and a study of disease development in a colony of specific pathogen-free cats indicate that, in at least some individuals, genetic predisposition (perhaps resulting in a heritable dysfunction of eosinophilic regulation) is a significant component for development of eosinophilic granuloma and indolent ulcer
- Lesions of all four syndromes may develop spontaneously and acutely
- Development of eosinophilic plaques can be preceded by periods of lethargy
- A seasonal incidence is common and may indicate insect or environmental allergen exposure
- Waxing and waning of clinical signs is common in all four syndromes
- Development of eosinophilic plaques can be preceded by periods of lethargy
- Eosinophilic plaque: hypersensitivity reaction, most often to insects (fleas, mosquitoes); less often to food or environmental allergens; exacerbated by mechanical trauma
- Eosinophilic granuloma: multiple causes, including genetic predisposition and, possibly, hypersensitivity
- Indolent ulcer: may have both hypersensitivity and genetic causes
- Allergic miliary dermatitis: very common hypersensitivity reaction, most often to fleas
- EGD: may have both a genetic predisposition and a hypersensitivity cause (especially in nongenetically susceptible breeds)
- Skin/exocrine: the integument is most often affected
- Oral cavity
- Eosinophilic granuloma can affect the tongue, palatine arches, and palate
- EGD: most often affects the tongue and palatine arches; reported cutaneous lesions on the prepuce and flanks
- Eosinophilic granuloma can affect the tongue, palatine arches, and palate
SIGNALMENT/HISTORY
- The true complex restricted to cats
- Indolent ulcer: no age predisposition reported
- Cats: predilection for females has been reported only for indolent ulcer
- Genetically initiated eosinophilic granuloma: <2 years of age
- Allergic disorder: >2 years of age
- Eosinophilic plaque: 2–6 years of age
- Indolent ulcer: no age predisposition reported
- Eosinophilic granulomas (EGD) occur in dogs and other species, but are not considered part of this disease complex
- Siberian huskies (76% of cases), Cavalier King Charles spaniel, possibly German Shepherd
- Usually <3 years of age
- Males (72% of cases)
- Siberian huskies (76% of cases), Cavalier King Charles spaniel, possibly German Shepherd
CLINICAL FEATURES
- Distinguishing among the syndromes depends on both clinical signs and histopathologic findings
- Lesions of more than one syndrome may occur simultaneously
- Eosinophilic granulomas: occasionally overlapping presentations
- Distinctly linear orientation (linear granuloma) on the caudal thigh
- Individual or coalescing plaques located anywhere on the body; ulcerated with a “cobblestone” or coarse pattern, white or yellow, possibly representing collagen degeneration
- Lip margin and chin swelling (“pouting”)
- Footpad swelling, pain, and lameness (most common in cats under 2 years of age)
- Oral cavity ulcerations (especially on the tongue, palate, and palatine arches) (Fig. 59-1)
- Cats with oral lesions may be dysphagic, have halitosis, and may drool
- Distinctly linear orientation (linear granuloma) on the caudal thigh
- Eosinophilic plaques
- Alopecic, erythematous, erosive patches, and plaques or well-demarcated, steep-walled plaques
- Usually occur in the inguinal, perineal, lateral thigh, and axillary regions
- Frequently moist or glistening
- Regional lymphadenopathy common
- Alopecic, erythematous, erosive patches, and plaques or well-demarcated, steep-walled plaques
- Lesion development may stop spontaneously in some cats, especially with the heritable form of eosinophilic plaque
- Indolent ulcers
- Classically concave and indurated ulcerations with a granular, orange-yellow color, confined to the upper lips adjacent to the philtrum (Fig. 59-2)
- EGD: ulcerated plaques and masses; dark or orange color
- Most often affects the tongue and palatine arches
- Reported cutaneous lesions on the prepuce and flanks
- Most often affects the tongue and palatine arches
- Allergic miliary dermatitis: multiple brown/black crusted and erythematous paupules; lesions more often palpated than visualized; may be associated with alopecia; usually associated with pruritis; frequently affects the dorsum
