JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

September 2025

I-N04B

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

HISTORY: Mass from the toe.

HISTOPATHOLOGIC DESCRIPTION: Digit (per contributor): Arising from the hyperplastic and ulcerated epidermis, extending to deep margins, and infiltrating preexisting bone is a densely cellular, unencapsulated, infiltrative neoplasm composed of anastomosing cords, trabeculae, and islands of polygonal cells supported by a moderate collagenous to desmoplastic stroma. Neoplastic cells have distinct cell borders with prominent intercellular bridges, abundant brightly eosinophilic cytoplasm, and an irregularly round to oval nucleus with finely stippled chromatin and 1-3 prominent magenta nucleoli. Anisokaryosis and anisocytosis are moderate and there are 52 mitotic figures per 2.37mm² with occasional atypical mitotic figures. Neoplastic cells frequently exhibit dyskeratosis characterized by individualized cells within the stratum spinosum with brightly eosinophilic cytoplasm and pyknosis. There are multifocal keratin pearls characterized by brightly eosinophilic central accumulations of compact lamellations of keratin. Within the stroma of the neoplasm, there are low numbers of melanin-laden macrophages, scattered lymphocytes, and plasma cells. Multifocally, neoplastic cells invade and replace preexisting bone in which existing bony trabeculae are lined by increased numbers of osteoclasts in resorption bays (Howship's lacunae) (osteolysis) and multiple foci of woven bone lined by plump osteoblasts (reactive bone formation). There is multifocal ulceration of the overlying epidermis with replacement 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, breed not specified, canine.

Slide B: Signalment (JPC #1619769) 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 a 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 a moderate amount of fibrovascular to often desmoplastic stroma. Neoplastic cells have distinct cell borders with prominent intercellular bridges, abundant amphophilic to eosinophilic cytoplasm, irregularly round to oval nuclei with finely stippled chromatin, and 1 to 4 distinct magenta nucleoli. Anisocytosis and anisokaryosis are moderate and mitotic figures average 48 per 2.37mm² with occasional atypical mitotic figures. Cords and islands often contain central, compact, eosinophilic lamellations of keratin (keratin pearls). Multifocal hair follicles and adnexa are surrounded by numerous lymphocytes, plasma cells, and neutrophils. There is focally extensive epidermal ulceration characterized by epidermal loss and replacement by a serocellular crust composed of fibrin, proteinaceous fluid, and neutrophils subtended by, lymphocytes, plasma cells, histiocytes, neutrophils, small caliber blood vessels and numerous fibroblasts contiguous with haphazardly arranged collagen bundles (granulation tissue). The remaining epithelium is markedly hyperplastic characterized by anastomosing rete ridges, an expanded stratum spinosum (acanthosis), and a stratum corneum markedly thickened by parakeratotic and orthokeratotic hyperkeratosis. Within the subcutis, there is moderate multifocal hemorrhage, fibrin, and increased clear space (edema).

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

Slide C: Signalment (JPC #4090973) 13-year old female domestic European shorthair cat.

HISTORY: Affected skin displayed a plaque-like lesion with irregular edges.

HISTOPATHOLOGIC DESCRIPTION: Haired skin: Approximately 80% of the epidermis is markedly thickened by a poorly demarcated, moderately cellular, unencapsulated, and expansile intraepidermal neoplasm, which extends into the outer root sheath of underlying hair follicles. Within this area, the epidermis is expanded up to 8-10 cell layers thick by a monomorphic population of cells undergoing disorganized maturation and forming broad, nodular rete ridges, which are constrained by a basement membrane. Neoplastic cells have distinct cell borders, an abundant amount of eosinophilic cytoplasm, which occasionally contains granular golden pigment (melanin), irregularly round to oval nuclei with finely stippled chromatin and up to four prominent nucleoli. Anisocytosis and anisocytosis are moderate and mitoses average 12 per 2.37mm². Multiple follicles lined by neoplastic epithelial cells are empty or contain fragmented hair shafts admixed with lamellated keratin admixed with few neutrophils, amorphous karyorrhectic and cellular debris, scant hemorrhage, and fibrin. The neoplastic epithelium is multifocally eroded with a serocellular and hemorrhagic crust, infiltrated by low numbers of neutrophils, and in these areas, neoplastic epithelial cells are markedly expanded by intracellular edema to variable depths. There is similar but less severe cellular atypia at the periphery of the lesion with less prominent rete ridges and re-establishment of normal epithelial maturation. The superficial dermis is markedly expanded by congested vessels, numerous viable and degenerate neutrophils (also in perifollicular and periadnexal locations), cellular debris, and variable amounts of hemorrhage, edema, and fibrin.

MORPHOLOGIC DIAGNOSIS: Haired skin: Bowenoid in situ carcinoma, domestic European shorthair cat, feline.

GENERAL DISCUSSION:

• Squamous cell carcinoma (SCC) is the most common malignant skin neoplasm in cats; second most common in dogs, following mast cell tumor
• SCC is the second most common oral tumor in dogs
• Invasive squamous cell carcinomas (ISCC) are the most common malignant cutaneous neoplasms of cats
• Arises from keratinocytes and commonly occurs in sun-damaged skin
• Solar induced SCC is usually preceded by actinic keratosis; other factors that can influence its occurrence include carcinogens, genetic factors, papillomaviruses, and epidermal trauma (e.g. ear notching, branding, burns and chronic inflammation)
• Predisposing factors include chronic UV exposure, lack of pigment, and thin haircoat in affected areas; most common in middle aged to older animals
• Highest incidence among short haired breeds with little skin pigmentation in both dogs and cats (predisposed dog breeds include Dalmatians, pit bull terriers, harlequin great Danes, and beagles); SCC in pigmented areas more often are associated with papillomavirus
• Claw bed (subungual): Most common neoplasm of the digit in dogs and cats; often more aggressive with multiple digits affected and usually associated with large breed, black-coated dogs (especially Labrador retriever, standard poodles, giant schnauzers, dachshunds, Briards, Beaucerons and Bouvier de Flanders); case report of pigmented subungual SCC in a dog (Yang et al., 2022)
  • Multicentric squamous cell carcinoma in situ (bowenoid in situ carcinoma [BISC]):
  • refers to a malignant tumor of cells with squamous differentiation that is confined by the basement membrane
  • Middle aged to older mixed-breed cats
  • Found in haired-pigmented skin and is unrelated to sunlight exposure; has been predominantly by Felis catus papillomavirus 2 (FcaPV-2)
• Papillomaviruses induce and/or are associated with several types of cutaneous lesions, including squamous papilloma, inverted papilloma, feline viral plaques, canine pigmented viral plaques, bowenoid in situ carcinoma (BISC), invasive squamous cell carcinoma (ISCC)
• The potential for transformation to bowenoid in situ carcinoma (BISC), and ISCC has been reported in lesions infected with CPV-3

PATHOGENESIS:

• Ultraviolet (UVB) radiation is the most important carcinogenic stimulus for cutaneous SCC
  • UV light > formation of pyrimidine dimers (cytosine, uracil, thymine) in DNA > nucleotide repair pathway is overwhelmed > some DNA damage remains unrepaired > transcriptional errors > neoplasia
  • UV light > tumor suppressor gene mutations, particularly P53
  • UV light suppresses neoplasia suppressing immune-responses
• Other associated carcinogens include tobacco, coal tar, soot, arsenic, and smegma
• Structural antigens from papillomavirus have been found in SCC of multiple species suggesting a possible etiologic role
  • Proposed pathogenesis: UV light damage to DNA of a papillomavirus-infected epithelial cell > viral inhibition of p53 prevents DNA repair and apoptosis > viral-induced epithelial proliferation > increased replication of neoplasia-prone cells
• Usually a progression, over months to years, from epidermal plaques, solar keratosis, and papillomas > carcinoma in situ > SCC

TYPICAL CLINICAL FINDINGS:

• Solar induced SCC often arises in hypopigmented and/or sparsely haired regions:
  • Dogs: Ventral trunk, limbs, digits, scrotum, and lips; nasal planum rarely affected, usually associated with depigmentation if affected (e.g. discoid lupus erythematosus)
  • Cats: Nasal planum, pinnae, and eyelid
• Locally invasive and destructive; solar induced tend to be slow to metastasize (usually restricted to local lymph nodes); however, canine digital SCCs are more prone to metastasis but are also typically amenable to cure with excision
• May metastasize to the lungs and regional lymph nodes

TYPICAL GROSS FINDINGS:

• Variably sized; poorly demarcated; firm; white; nodular, papillary, alopecic, plaque-like, or crateriform masses that are often ulcerated and erythematous
• Cutaneous horns may arise from viral papillomas and squamous cell carcinoma (bowenoid in situ or invasive)
  • Cutaneous horns are rare exophytic cylindrical formations of compact keratin a few millimeters in diameter and 1-2 cm in length, formed by an underlying markedly hyperplastic epithelium.
    • Orthokeratotic hyperkeratosis predominates
• BISC: multiple crusting, hyperpigmented, roughly circular plaques

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Tumor cells breach the basement membrane to form islands, cords, and trabeculae within the dermis that are usually contiguous with the overlying epidermis; there is often formation of keratin pearls (concentric lamellae of keratin) and prominent intercellular bridges; poorly differentiated tumors may only exhibit keratinization of individual cells (dyskeratosis)
• Vesicular nuclei with one or multiple very prominent nucleoli; cytoplasm is typically abundant and eosinophilic
• Invasion is usually associated with marked desmoplasia; mitotic figures are often numerous and proportional to degree of anaplasia
• Spindle cell SCC:
  • Uncommon variant: Large, pleomorphic, fusiform to polygonal epithelial cells are difficult to differentiate from stromal cells but are often positive for cytokeratin; recent report (Guisado et al., 2021) identified predilection for occurrence on the face (pinna>periorbital>dorsal muzzle) and often positive for p63, CK5/6, and AE1/AE3, and negative for CK8/18; also identified association with solar exposure due to presence actinic keratosis
• Bowenoid in situ carcinoma:
  • Malignant change confined to the epidermis without breaching the basement membrane
  • Abrupt hyperplasia and dysplasia of the epidermis and follicular outer root sheath that remain confined to the basement membrane
    • Keratin pearl formation may be present
    • Large hyperchromatic nuclei and may have vacuolated cytoplasm, cytoplasmic pallor, or occasionally are multinucleated
    • Dysplastic cells have elongated nuclei that tend to orient in one direction (“wind-blown”) appearance

ADDITIONAL DIAGNOSTIC TESTS:

• Cytology:
  • Immature or dysplastic squamous epithelial cells accompanied by purulent inflammation; emperipolesis associated with well-differentiated SCC
  • “Tadpole” shaped epithelial cells with blue-green hyalinized cytoplasm; may be arranged individually or in sheets; moderate to well-differentiated neoplastic cells may have perinuclear vacuolization (colorless keratohyalin granules)
  • Well-differentiated tumors typically have highly keratinized, nucleated, and angular epithelial cells vs. moderately-differentiated SCCs with >50% round or oval dysplastic cells vs. poorly-differentiated SCCs with predominately round individualized cells with high N:C; lack of marked atypia does not exclude malignancy
• Immunohistochemistry:
  • Most carcinomas are positive for cytokeratin which may be helpful in differentiating SCC from other anaplastic neoplasms
  • SCCs in dogs are positive for cytokeratin 6 and 10, which can be helpful in distinguishing them from some basosquamous variants
• In cats, membrane expression of E-cadherin and b-catenin is reduced in most feline cutaneous SCCs, suggesting that epidermal cells decrease the expression of these adhesion proteins during neoplastic transformation (Sanz et al. 2023)

DIFFERENTIAL DIAGNOSIS:

• Histologic differential diagnosis:
  • Cutaneous:
    • Squamous cell carcinoma in situ: Confined by the basement membrane
    • Basosquamous carcinoma: Low-grade malignant tumor comprised primarily of dermal lobules of basaloid cells with centralized foci of atypical abruptly keratinized cells; +/- CK16 immunoreactivity
    • Papilloma (I-V01): Well-circumscribed, noninvasive
    • Infundibular keratinizing acanthoma (I-N01A): Well-circumscribed, noninvasive
    • Actinic keratosis (solar keratosis): Mildly elevated plaques in areas vulnerable to solar exposure comprised of thickened epidermis (predominantly deeper layers) with angular disorganize rete ridges +/- disorganization and crowding of stratum basale with loss of polarity; may exhibit dyskeratosis and solar elastosis; confined by the basement membrane and lacks cytopathic change; not always possible to differentiate from BISC in cats without IHCs
  • Subungual:
    • Keratoacanthoma (I-N31): Benign neoplasm of nailbed epithelium; lack of neoplastic cell invasion

COMPARATIVE PATHOLOGY:

• Cattle:
  • SCC: Common on the limbus, third eyelid, eyelids, conjunctiva pinna, back, distal limbs, and vulva; Herefords and Ayrshires are at increased risk
  • Ocular SCC is the most economically significant neoplasm of domestic animals
  • Carcinoma of the horn of cattle: Uncommon; almost exclusive to castrated male adult cattle in India and neighboring countries; infiltrates and destroys the horn core and may invade adjacent sinuses and cranial bone.
• Horses: Commonly affected locations include the penis, prepuce, periocular, and perianal regions
• Appaloosa, American paint horse, quarter horse, and males are predisposed
  • SCC is also found in the non-glandular stomach (this is the most common gastric neoplasm in horses, D-N08); rarely reported to arise in guttural pouch
• Sheep: Muzzle, lips, eyelids, perineum, vulva (in recently sheared sheep), pinnae; Merinos may be at increased risk
• Goats:
  • Predisposed sites include udder, perianal, horn base, pinnae, eyelid, vulva
  • Angoras and Boers potentially at increased risk
• Rabbits: 75% of Oryctolagus rabbits inoculated with cottontail rabbit papillomavirus (CRPV) (Shope papilloma virus), develop papillomas and often progress to SCC; Sylvilagus rabbits may also undergo malignant transformation, but to lesser degree; mechanical viral spread by insect vectors
• Captive reptiles: cutaneous SCC of serpents most commonly reported in cloacal region; digital SCC reported in estuarine crocodile
• Free-ranging reptiles: Case report of Emydoidea herpesvirus 2 (EBHV-2) associated mandibular SCC in a free-ranging Blanding’s turtle (Andersson et al. 2021)
• NHPs: Most common oral and esophageal tumor; Oral cavity > skin; perineum and sex skin are predisposed; SCC reported as the most common penile neoplasm of macaques in recent study (Kirejczyk et al. 2021); papillomavirus DNA similar to HPV-16 detected in a case of penile squamous cell carcinoma
• Cervids: Oral SCC reported in free ranging red-deer
• Camelids: Cutaneous SCC (and gastrointestinal SCC) reported in llamas and alpacas
• Non-domestic felids: Captive snow leopards overrepresented and associated with papillomavirus; oral > cutaneous SCC; most common cutaneous locations include face, forelimbs and feet are often immunopositive for PuPV-2; oral SCC may be induced by PuPV-1
• Bandicoots: Bandicoot papillomatosis and carcinomatosis viruses 1 and 2 associated with induction of premalignant changes and progression to invasive SCC; viruses are genetic intermediate between Papillomaviridae and Polyomaviridae; western barred and southern brown bandicoot affected by BPCV-1 and -2, respectively
• Bats: Multiple cutaneous papillomas and basosquamous/squamous cell carcinomas reported in a 5-year old captive Rousettus aegyptiacus with positive immunoreactivity for bovine papillomavirus
• Rodents: Associated with aricular chondritis in mice; one of the two most common cutaneous tumors of gerbils (with melanoma)
• Anurans: Most commonly reported in Northern leopard frogs
• Fish: Similar to mammalian SCC but lack keratin pearl formation

REFERENCES:

1. Andersson KE, Adamovicz L, Mumm LE, et al. Detection of a novel herpesvirus associated with squamous cell carcinoma in a free-ranging Blanding's turtle. J Vet Diagn Invest. 2021;33(2):348-351.
2. Agnew D. Camelidae. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:193.
3. Bacci B, Martinoli G, Gallina L, et al. Immune cell analysis in equine penile papilloma, in situ squamous cell carcinoma and invasive squamous cell carcinoma: FoxP3+ T regulatory lymphocytes differ according to equine papillomavirus 2 status. Vet Pathol. 2025.
4. Barthold SW, Griffey SM, Percy, DH. Pathology of Laboratory Rodents and Rabbits. Ames, IA. Wiley Blackwell; 2016:210, 260.
5. Barrantes Murillo DF, Berrocal A, Stranahan LW, Brinker EJ, Craig LE, Negrão Watanabe TT. Beak neoplasia in avian species: description of nine cases. J Comp Pathol. 2025;221:35-39.
6. Brady AG, Carville AAL. Digestive system disease of nonhuman primates. In: Abee CR, Mansfield K, Tardif S, et al. Nonhuman primates in biomedical research: Diseases. Vol 2. San Diego, CA: Academic Press; 2012:593-4.
7. Brito Junior JRC, Soares YGS, Soares LA, et al. Primary intracranial squamous cell carcinoma in a mule. J Comp Pathol. 2025;218:37-40.
8. Conley KJ, Shilton CM. Crocodilia. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:859.
9. Farina LL, Lankton JS. Chiroptera. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:615.
10. Fisher DJ. Cutaneous and subcutaneous lesions. In: Valenciano AC, Cowell RL, eds. Diagnostic Cytology and hematology of the dog and cat. 5th ed. St. Louis, MO: Elsevier; 2020:92-3.
11. Frasca S, Wolf JC, Kinsel MJ, Camus AC, Lombardini ED. Osteichthyes. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:959.
12. Higgins D, Rose K, Spratt D. Monotremes and marsupials. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:466.
13. Howerth EW, Nemeth NM, Ryser-Degiorgis MP. Cervidae. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:156.
14. Kirejczyk S, Pinelli C, Gonzalez O, Kumar S, Dick E Jr, Gumber S. Urogenital Lesions in Nonhuman Primates at 2 National Primate Research Centers. Vet Pathol. 2021;58(1):147-160.
15. Kramer JA, Bielitzki J. Integumentary system diseases of nonhuman primates. In: Abee CR, Mansfield K, Tardif S, et al. Nonhuman primates in biomedical research: Diseases. Vol 2. San Diego, CA: Academic Press; 2012:580.
16. Labelle P. The Eye. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2017: 1409-1410.
17. Luff J, Weingart S, May S, Murphy B. A subset of equine oral squamous cell carcinomas is associated with Equus caballus papillomavirus 2 infection. J Comp Pathol. 2023;205:1-6.
18. 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. St. Louis, MO: Elsevier; 2016:706-714.
19. Mignacca SA, Agnello S, Castiglione S, Guercio A, Purpari G, Capucchio MT. Malignant skin neoplasms in goats in Sicily, Italy: clinical, virological and pathological investigations. J Comp Pathol. 2024;213:28-36. 
20. Miller AD. Neoplasia and proliferative disorders of nonhuman primates. In: Abee CR, Mansfield K, Tardif S, et al. Nonhuman primates in biomedical research: Diseases. Vol 2. San Diego, CA: Academic Press; 2012:330.
21. Munday JS, Bell CM, Gulliver EL. Feline oral in situ carcinoma associated with papillomavirus infection: A case series of 7 cats. Vet Pathol. 2025. 
22. Munday JS, Hardcastle M, Dally N. In situ squamous cell carcinoma of the gingiva and nictitating membrane associated with Felis catus papillomavirus type 3 in a cat. Vet Pathol. 2022;59(3):463-466.
23. Njaa BL. The Ear. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2017:1363.
24. Orlandi M, Mazzei M, Albanese F, et al. Clinical, histopathological, and molecular characterization of canine pigmented viral plaques. Vet Pathol. 2023;60(6):857-864.
25. Ossiboff RJ. Serpentes. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:907.
26. Pessier AP. Amphibia. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:932.
27. Raskin RE, Conrado FO. Integumentary system. In: Raskin RE, Meyer DJ, Boes KM, eds. Canine and Feline Cytopathology: A Color Atlas and Interpretation Guide. 4th ed. St. Louis, MO: Elsevier; 2023:67-9.
28. Rodríguez Guisado F, Suárez-Bonnet A, Ramírez GA. Cutaneous Spindle Cell Squamous Cell Carcinoma in Cats: Clinical, Histological, and Immunohistochemical Study. Vet Pathol. 2021;58(3):503-507.
29. Sanz Ressel BL, Gomez Castro G, Massone AR, Barbeito CG. Altered E-cadherin/β-catenin expression in feline cutaneous squamous cell carcinomas. J Comp Pathol. 2023;207:21-24.
30. Schmidt RE, Reavill DR, Phalen DN. Pathology of Pet and Aviary Birds. Ames, IA: John Wiley & Sons, Inc; 2015:28, 58, 63, 68, 254-5, 268, 274.
31. Steenkamp G, Tordiffe ASW, Suleman E, Oosthuizen A, Brettschneider H, Boy SC. Sublingual papillomas of cheetahs in southern Africa. Vet Pathol. 2022;59(6):997-1002.
32. Stidworthy MF, Denk D. Sphenisciformes, gaviiformes, podicipediformes, procellariiformes, pelecaniformes. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:662.
33. St. Leger J, Raverty S, Mena A. Cetacea. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018: 549-552.
34. Terio KA, McAloose D, Mitchell (nee Lane) E. Felidae. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:269, 272.
35. Trupkiewicz, Garner MM, Juan-Salles C. Passeriformes, Caprimulgiformes, Coraciiformes, Piciformes, Bucerotiformes, and Apodiformes. In: Terio K, McAloose D, Leger J, eds. Pathology of Wildlife and Zoo Animals, San Diego, CA: Elsevier 2018:804.
36. Wachtman L, Mansfield K. Viral diseases of nonhuman primates. In: Abee CR, Mansfield K, Tardif S, et al. Nonhuman primates in biomedical research: Diseases. Vol 2. San Diego, CA: Academic Press; 2012:34.
37. Welle MM, Linder KE. The integument. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2017: 1156, 1163-5, 1209.e1.
38. Womble M, Weingart S, May S, Garner M, Luff J. A putatively novel papillomavirus associated with cutaneous plaques and squamous cell carcinoma in captive North American snow leopards (Panthera uncia). Vet Pathol. 2024;61(6):973-977.
39. Yang Y, Go DM, Jung JH, et al. Subungual Pigmented Squamous Cell Carcinoma in a Dog. J Comp Pathol. 2022;194:50-53.
40. Wilcock BP, Njaa BL. Integumentary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. St. Louis, MO: Elsevier; 2016:500.
41. Womble M, Weingart S, May S, Garner M, Luff J. A putatively novel papillomavirus associated with cutaneous plaques and squamous cell carcinoma in captive North American snow leopards (Panthera uncia). Vet Pathol. 2024;61(6):973-977.

Click the slide to view.

---