Web Chapter 35 Canine oral papilloma (COP) is a self-limited infectious disease that is normally confined to mucosal tissue of the oral cavity or lips in young dogs, but it also can produce papillomas on the conjunctiva and external nares. The lesions begin as white, flat, smooth, shiny papules and plaques and progress to whitish-gray, pedunculated or cauliflower-like hyperkeratotic masses. Light microscopy reveals papillomatous proliferations of thick squamous epithelium in which some cells are swollen with vesicular cytoplasm. Canine oral PV (COPV)–induced generalized papillomas occasionally may be the presenting sign in immunocompromised and cyclosporine-administered dogs (Favrot et al, 2005). The lesions regress spontaneously in most cases, although malignant transformation into carcinomas has been reported. Cutaneous inverted papilloma (CIP) was described as single or several nonpigmented, raised, firm masses covered by skin with a central pore opening to the surface (Stokking et al, 2004). It is usually seen in dogs less than 3 years of age and occurs commonly on the ventral abdomen including the inguinal region. Lesions are less than 2 cm. Light microscopy shows an inverted flasklike structure with marked papillary projections from the wall into a keratin core. A possible subtype of CIP may exist, reported in middle-aged dogs as multiple whitish papules up to 4 mm at the neck and thorax that spontaneously regressed (Shimada et al, 1993; Lange et al, 2009). It also shows an inverted flasklike structure, but less papillary projections centripetally. PV-associated canine pigmented plaques (CPPL) occur in some pugs and miniature schnauzers during young adulthood (Le Net et al, 1997). Boston terriers, French bulldogs, and shar-peis, as well as immunocompromised individuals, are also suspected of having an increased incidence of this wart (Stokking et al, 2004). Lesions are multiple, scaly, deeply pigmented macules, plaques, and sometime papules commonly seen on the ventral neck, ventral trunk, and extremities. Histopathologically, it is characterized as demarcated, irregularly digitated acanthosis with marked hyperkeratosis and hyperpigmentation. In general, CPPL develop progressively over time and do not regress. The potential for transformation to squamous cell carcinoma (SCC) has also been reported. The presumed familial nature of CPPL suggests that it might be equivalent to epidermodysplasia verruciformis (EV) in humans. EV is considered genetically determined and is caused by unusual susceptibility to EV-specific human PV infection. PV-associated canine pigmented papules (CPPA) have been reported to occur in a boxer under long-term corticosteroid therapy (Le Net et al, 1997). Multiple black, rounded papules up to 2 mm were recognized on the ventral skin. A single lesion was also reported at the concaved aspect of pinna of a Rhodesian ridgeback (Lange et al, 2009). Light microscopy showed well-demarcated foci of epidermal endophytic hyperplasia and a markedly thickened, abnormally cornified layer. Viral cytopathic effect was characterized by enlarged cells in the epidermis. Spontaneous regression occurred within 3 weeks after cessation of corticosteroids.
Canine Papillomaviruses
Clinical Features
Canine Oral Papilloma
Cutaneous Inverted Papilloma
Canine Pigmented Plaques
Canine Pigmented Papules
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