Signalment (JPC #1869901) Slide A:  Age and breed unspecified dog

HISTORY:  Mass from the toe

HISTOPATHOLOGIC DESCRIPTION:  Digit (per contributor):  Arising from the hyperplastic and ulcerated epidermis and extending to deep dermal borders and infiltrating preexisting bone is an unencapsulated, infiltrative neoplasm composed of anastomosing cords, trabeculae, and nests of polygonal cells supported by a moderate collagenous stroma.  Neoplastic cells have distinct cell borders with prominent intercellular bridges, abundant brightly eosinophilic fibrillar cytoplasm, an irregularly round to oval nucleus with finely stippled chromatin and 1-3 magenta nucleoli.  There is moderate anisokaryosis and anisocytosis.  The mitotic rate averages 2 per HPF with occasional bizarre mitotic figures.  Frequent neoplastic cells exhibit dyskeratosis with brightly eosinophilic cytoplasm and pyknosis.  There are multifocal keratin pearls, characterized by brightly eosinophilic central accumulations of compact lamellations of keratin.  Nests of neoplastic cells are often surrounded by desmoplasia, with fibrous connective tissue and reactive fibroblasts.  Within the stroma of the neoplasm, there are low numbers of melanomacrophages, scattered lymphocytes, and plasma cells.  Multifocally, neoplastic cell invade and replace preexisting bone with existing bony trabeculae lined by increased numbers of osteoclasts in Howship's lacunae (osteolysis) and multiple foci of woven bone lined by plump osteoblasts (reactive bone).  Extensively the ulcerated epidermis is replaced by a serocellular crust composed of cellular debris, high numbers of neutrophils, hemorrhage, proteinaceous fluid, and fibrin.

MORPHOLOGIC DIAGNOSIS:  Digit (per contributor):  Squamous cell carcinoma, subungual, with osteolysis and reactive bone, breed not specified, canine.

Signalment (JPC #1619769), Slide B:  Seven-year-old beagle

HISTORY:  Abdominal skin from a beagle that was one of a large colony housed in outdoor kennels in Colorado

HISTOPATHOLOGIC DESCRIPTION:  Haired skin, abdomen (per contributor):  Arising from the hyperplastic and ulcerated epidermis and extending to the deep dermis is a poorly circumscribed, unencapsulated, infiltrative neoplasm composed of polygonal cells arranged in cords, trabeculae, and islands, with occasional individualized cells supported by moderate amounts of fibrovascular stroma. Neoplastic cells have variably distinct cell borders with abundant amphophilic to eosinophilic cytoplasm and prominent intercellular bridges.  Nuclei are irregularly round to oval with finely stippled chromatin and 1-4 distinct magenta nucleoli.  The mitotic rate averages 3 per HPF with occasional bizarre mitotic figures.  There is moderate anisokaryosis and anisocytosis.  Cords and islands often contain keratin pearls with central, compact eosinophilic lamellations of keratin.  There is frequent desmoplasia.  Multifocally surrounding follicles and adnexa are many lymphocytes, plasma cells and neutrophils.  The epidermis is focally extensively ulcerated and replaced by a serocellular crust composed of fibrin, proteinaceous fluid, and neutrophils subtended by reactive fibroblasts, lymphocytes, plasma cells, histiocytes and neutrophils.  There is moderate parakeratotic and orthokeratotic hyperkeratosis. Within the subcutis, there is moderate multifocal hemorrhage, fibrin, and increased clear space (edema).

MORPHOLOGIC DIAGNOSIS:  1.  Haired skin, abdomen (per contributor):  Squamous cell carcinoma, beagle, canine.










Papilloma viruses associated with pre-neoplastic and neoplastic skin lesions in animals (adapted from Munday and Kiupel):

Animal species

Skin lesion



Feline viral plaque progressing to BISC

FdPV-1, -2





Canine pigmented viral plaque progressing to ISC and SCC

CfPV-3, -4


Endophytic papilloma and SCC in immunosuppressed dogs



Vaccine-induced cutaneous SCC



Equine sarcoid

BPV-1, -2


Equine papillomas, ISC and SCC



Cutaneous SCC


Western barred Bandicoot

Cutaneous SCC


Egyptian fruit bat

Basosquamous carcinoma


Natal multimammate mouse

Keratoacanthoma and SCC


European harvest mouse

Sebaceous carcinoma



FdPV, Felis domesticus papillomavirus; CfPV, Canis familiaris papillomavirus; COPV, canine oral papillomavirus; BPV, bovine papillomavirus; CRPV, cotton-tail rabbit papillomavirus; RaPV, rousettus aegyptiacus papillomavirus type I; MnPV, Mastomys natalensis papillomavirus; EcPV2, equine papillomavirus type 2



  1. Bardagi M, Fondevila D, Ferrer L. Immunohistochemical detection of COX-2 in feline and canine actinic keratoses and cutaneous squamous cell carcinoma. J Comp Pathol. 2012;146:11-17.
  2. Belluco S, Brisebard E, et al. Digital squamous cell carcinoma in dogs: epidemiological, histological, and immunohistochemical study. Vet Pathol. 2013;50(6):1078-82.
  3. Bomhard W, Goldschmidt MH, Shofer FS, Perl L, Rosenthal KL, Mauldin EA. Cutaneous neoplasms in pet rabbits: A retrospective study. Vet Pathol. 2007;44:579-588.
  4. Favrot C, Welle M, Heimann M, Godson DL, Guscetti F. Clinical, histologic, and immunohistochemical analyses of feline squamous cell carcinoma in situ. Vet Pathol. 2009;46:25-33.
  5. Goldschmidt MH, Dunstan RW, Stannard AA, von Tscharner C, Walder EJ, Yager JA: Histological classification of epithelial and melanocytic tumors of the skin of domestic animals. In:  Schulman FY, ed. Armed Forces Institute of Pathology, American Registry of Pathology, and The World Health Organization Collaborating Center, Washington, D.C.;1998:20-21.
  6. Gross TL, Ihrke PJ, Walder EJ, Affolter VK: Epithelial neoplasms and other tumors. In: Skin Diseases of the Dog and Cat. 2nd ed. Ames, IA: Blackwell Science; 2005:581-589.
  7. Hargis AM, Ginn PE. The integument. In: McGavin MD, Zachary JF, ed. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, Missouri: Mosby; 2012: 1013-1014,1078-1084.
  8. Klobukowska HJ, Munday JS. High numbers of stromal cancer-associated fibroblasts are associated with a shorter survival time in cats with oral squamous cell carcinoma.  Vet Pathol.  2016 Mar 3. pii: 0300985816629713. [Epub ahead of print]
  9. Lange CE, Tobler A, Lehner P, et al. EcPV2 DNA in equine papillomas and in situ and invasive squamous cell carcinomas supports papillomavirus etiology. Vet Pathol. 2013;50:686-694.
  10. Lohr CV. One hundred two tumors in 100 goats (1987-2011). Vet Pathol. 2013;50:668-675.
  11. Martin CK, Tannehill-Gregg SH, Wolfe TD, Rosol TJ. Bone-invasive oral squamous cell carcinoma in cats: Pathology and expression of parathyroid hormone-related protein. Vet Pathol. 2011;48:302-313.
  12. Mauldin EA and Peters-Kennedy J. Integumentary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. Philadelphia, Pennsylvania: Elsevier; 2015:711-714.
  13. Mestrinho LA, et al. p63 and E-cadherin expression in canine oral squamous cell carcinoma.  Vet Pathol. 2015;52(4):614-20.
  14. Millanta F, Andreani G, et al. Correlation between cyclo-oxygenase-2 and vascular endothelial growth factor expression in canine and feline squamous cell carcinomas.  J Comp Path. 2016;154:297-303.
  15. Munday JS, Aberdein D. Loss of retinoblastoma protein, but not p53, is associated with the presence of papillomaviral DNA in feline viral plaques, bowenoid in situ carcinomas, and squamous cell carcinomas. Vet Pathol. 2012;49:538-546.
  16. Munday JS, Benfell MW, et al. Bowenoid in situ carcinomas in two Devon Rex cats: Evidence of unusually aggressive neoplasm behaviour in this breed and detection of papillomaviral gene expression in primary and metastatic lesions. Vet Dermatol. 2016;27(3):215-e55.
  17. Munday JS, Fairley R, Atkinson K. The detection of Felis catus papillomavirus 3 DNA in a feline bowenoid in situ carcinoma with novel histologic features and benign clinical behavior.  J Vet Diagn Invest. 2016;28(5):612-5.
  18. Munday JS, French AF, Peters-Kennedy J, Orbell GB, Gwynne K. Increased p16 protein within feline cutaneous viral plaques, bowenoid in situ carcinomas, and a subset of invasive squamous cell carcinomas. Vet Pathol. 2011;48:460-465
  19. Munday JS, Kiupel M. Papillomavirus-associated cutaneous neoplasia in mammals. Vet Pathol. 2010;47:254-264
  20. Nemec A, Murphy BG, et al. Oral papillary squamous cell carcinoma in twelve dogs.  J Comp Pathol. 2014 Feb-Apr;150(2-3):155-61.
  21. Zhu KW, Affolter VK, et al. Equine genital squamous cell carcinoma: In situ hybridization identifies a distinct subset containing Equus caballus papillomavirus 2. Vet Pathol. 2015;52(6):1067-1072.

Click the slide to view.

Click on image for diagnostic series.

Back | Home | Contact Us | Links | Help |