Fantastic Case #1
Pigmented epidermal plaques in dogs
As you can see in the gross photo, there are several, raised dark plaques and these correlate with the changes seen in the adjacent photomicrograph that has a section of superficial skin with thickened epidermis that has irregular scalloping (papilliform hyperplasia), orthokeratotic hyperkeratosis, hyperpigmentation and melanophage accumulation in the dermis. There is increased prominence of keratohyalin (superficial epidermal, dark blue) granules, but not distinct koilocytes (no pale, vacuolated epithelial cells in the epidermis).
These are histologic and clinical features of pigmented epidermal viral plaques. An association with papillomavirus has been identified in these lesions. Pugs and Miniature Schnauzers are predisposed and there may also be hereditary factors. Boston Terriers and
French Bulldogs also have an increased incidence of these lesions. Lesions are often multiple and, uncommonly, there is progression to squamous carcinoma in situ or more invasive squamous carcinoma (see Fantastic Case #2).
References: Christian E Langem et al. A case of a canine pigmented plaque associated with the presence of a
Chi-papillomavirus. Vet Dermatol. February 2012;23(1):76-80, e18-9.
Tobler K et al. Detection of a novel papillomavirus in pigmented plaques of four Pugs. Vet Derm 19:21-25, 2008.
Pigmented epidermal plaques in dogs
As you can see in the gross photo, there are several, raised dark plaques and these correlate with the changes seen in the adjacent photomicrograph that has a section of superficial skin with thickened epidermis that has irregular scalloping (papilliform hyperplasia), orthokeratotic hyperkeratosis, hyperpigmentation and melanophage accumulation in the dermis. There is increased prominence of keratohyalin (superficial epidermal, dark blue) granules, but not distinct koilocytes (no pale, vacuolated epithelial cells in the epidermis).
These are histologic and clinical features of pigmented epidermal viral plaques. An association with papillomavirus has been identified in these lesions. Pugs and Miniature Schnauzers are predisposed and there may also be hereditary factors. Boston Terriers and
French Bulldogs also have an increased incidence of these lesions. Lesions are often multiple and, uncommonly, there is progression to squamous carcinoma in situ or more invasive squamous carcinoma (see Fantastic Case #2).
References: Christian E Langem et al. A case of a canine pigmented plaque associated with the presence of a
Chi-papillomavirus. Vet Dermatol. February 2012;23(1):76-80, e18-9.
Tobler K et al. Detection of a novel papillomavirus in pigmented plaques of four Pugs. Vet Derm 19:21-25, 2008.
