Papillomatosis
Issues
Papillomatosis
OVERVIEW
Cutaneous mucous membrane lesions of dogs and cats caused by various papilloma viruses.
Dogs: oral papillomatosis, venereal papillomatosis, exophytic cutaneous papillomas, cutaneous inverted papillomas, multiple papillomas of the footpad, canine pigmented viral plaques.
Cats: feline cutaneous papillomas, feline cutaneous fibropapillomas (feline sarcoids), feline viral plaques.
Viral plaques may progress to BISC, SCC or invasive carcinoma.
SIGNALMENT
Dogs
Puppies and young adult dogs—oral papillomatosis, venereal papillomatosis, multiple papillomas of the footpad, cutaneous inverted papillomas, canine pigmented viral plaques (breed predisposition).
Older dogs—exophytic cutaneous papillomas, cutaneous inverted papillomas.
Miniature schnauzers and pugs—pigmented viral plaques; associated with immunosuppression in other breeds.
Cats
More common in older cats; associated with immunocompromise (e.g., FIV).
Feline sarcoids: younger cats, especially those with outdoor exposure.
SIGNS
Dogs
Cutaneous papillomas—pedunculated, fronds of epithelium, up to 1 cm in diameter located anywhere.
Canine papillomavirus—most often oral mucosa, hard palate, epiglottis; may interfere with prehension, swallowing; trauma results in halitosis and ptyalism; may be confined to genital or eyelid regions.
Cutaneous inverted papillomas—less common, multiple lesions often found with a central pore; on ventral abdomen; caused by distinctly different papilloma virus from COPV.
Multiple papillomas affecting footpads in younger dogs—firm, hyperkeratotic lesions causing discomfort and lameness.
Canine pigmented viral plaques—miniature schnauzers, pugs; Boston terriers, French bulldogs; rarely transform to SCC; ventral abdomen and inner thigh region.
Cats
Feline cutaneous papillomas—rare.
Feline viral plaques—more common; may progress to BISC or invasive carcinoma.
Feline sarcoid lesions—uncommon.
Cats 10 years or older; other systemic disease causing immunosuppression (e.g., FIV).
CAUSES & RISK FACTORS
Oral papillomas affecting naive dogs and recovered animals develop lifelong immunity.
Dogs—cutaneous papillomas thought to involve cell-mediated immunologic defects.
Older, immunosuppressed cats develop plaques and BISC.
Canine pigmented viral plaques—strong breed predisposition.
DIAGNOSIS
DIFFERENTIAL DIAGNOSIS
Dogs
Oral cavity, oropharynx—fibromatous epulis, transmissible venereal tumor, SCC.
Cutaneous—sebaceous hyperplasia, acrochordon.
Pigmented plaque—melanocytoma.
Inverted—infundibular keratinizing acanthoma.
Cats
Eosinophilic granuloma, complex, actinic keratoses, cutaneous lesions of FeLV, multicentric SCC in situ, SCC.
CBC/BIOCHEMISTRY/URINALYSIS
Normal
OTHER LABORATORY TESTS
Cats: FeLV, FIV
IMAGING
N/A
DIAGNOSTIC PROCEDURES
Gross lesions have a typical appearance.
Biopsy for histopathology; immunohistochemistry demonstrates viral antigens within lesions; PCR not definitive.
PATHOLOGIC FINDINGS
Dependent upon syndrome; all lesions share cytopathic effects of papillomavirus infection: hyperkeratosis, acanthosis, koilocytes in stratum spinosum, abnormal, large keratohyalin granules in statum granulosum.
Viral pigmented plaques may lack koilocytes and viral inclusion bodies.
TREATMENT
Most lesions regress spontaneously (especially oral forms).
Surgery if needed (excision, cryosurgery, or electrosurgery).
Persistent disease (dogs)—COPV vaccine reported to induce epithelial tumors and SCC at vaccination sites; latency period 11–34 months; autogenous vaccination: treatment controversial.
Cats—diagnosis for visceral diseases or causes of immunosuppression.
MEDICATIONS
DRUG(S)
α-Interferon—30 units/cat PO q24h.
Imiquimod—applied to individual lesions three times/week for 4 weeks.
CONTRAINDICATIONS/POSSIBLE INTERACTIONS
Imiquimod—potential for human exposure when applying to patient; causes severe localized reaction; use with caution at mucocutaneous junctions.
FOLLOW-UP
PATIENT MONITORING
Monitor for signs of malignant transformation to SCC.
PREVENTION/AVOIDANCE
Separate dogs with oral papillomas from susceptible animals.
Commercial kennels—may consider autogenous vaccination.
EXPECTED COURSE AND PROGNOSIS
Dogs—prognosis good; incubation period 1–8 weeks; regression usually 1–5 months; lesions persist 24 months or more.
Cats—long-term prognosis for plaques and BISC depends on concurrent diseases.
MISCELLANEOUS
AGE-RELATED FACTORS
Dependent upon viral strain
ZOONOTIC POTENTIAL
Papillomaviruses: species specific
PREGNANCY/FERTILITY/BREEDING
Venereal lesions may preclude breeding.
Transmission of viral infection likely; especially when active lesions present.
ABBREVIATIONS
BISC = bowenoid in situ carcinoma
COPV = canine oral papillomavirus
FeLV = feline leukemia virus
FIV = feline immunodeficiency virus
PCR = polymerase chain reaction
PV = papilloma virus
SCC = squamous cell carcinoma
Visit your veterinarian as early recognition, diagnosis, and treatment are essential.
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