JPC SYSTEMIC PATHOLOGY
Signalment (JPC #1818935): White-tailed deer (Odocoileus virginianus)
HISTORY: Proliferative dermal mass
HISTOPATHOLOGIC DESCRIPTION: Haired skin: Expanding the dermis, elevating the overlying mildly hyperplastic epidermis and extending to cut borders is a moderately cellular neoplasm composed of spindle cells arranged in long interlacing streams and bundles on a moderate collagenous matrix. Neoplastic cells have indistinct cell borders, scant amount of pale eosinophilic, fibrillar cytoplasm, one oval to fusiform, vesiculate nucleus with finely stippled chromatin, and one variably distinct nucleolus. There is mild anisocytosis and anisokaryosis. The mitotic rate is 1 per 10 hpf. There is mild epidermal acanthosis with rete ridge formation and orthokeratosis. There are multiple macrophages which contain intracytoplasmic melanin (pigmentary incontinence) in the superficial dermis.
MORPHOLOGIC DIAGNOSIS: Haired skin: Fibropapilloma, White-tailed deer (Odocoileus virginianus), cervid.
ETIOLOGY: Deer papillomavirus (DPV)
ETIOLOGIC DIAGNOSIS: Cutaneous cervid papillomaviral fibropapillomatosis
- Cutaneous fibroma or fibropapilloma is one of the most commonly reported tumors of white-tailed deer
- Occurs most frequently in adult deer less than 2.5 years of age
- Greater prevalence in males; likely associated with injuries due to fighting
- Papillomaviruses are generally species specific
- In cervids there are six different viruses identified with five of those characterized that include deer papillomavirus, European elk papillomavirus, reindeer papillomavirus, and novel roe deer papillomavirus
- Papillomavirus is a 50-55 nm diameter, non-enveloped, double stranded DNA virus and most are species specific (see exception below)
- Other cervids as well as moose and caribou are also affected
- Usually an incidental finding
- Papillomavirus genera:
- Alpha papillomaviruses include oncogenic mucosal types
- Beta papillomaviruses includes lesions that may be associated with immunosuppression
- Delta papillomaviruses is associated with benign fibropapillomas in cats and ungulates (these have the unique ability to infect multiple species)
- Direct contact with contaminated surfaces or materials that might abrade the skin (e.g. scratching posts, sparring)
- Lesions begin to develop 30 days after inoculation
- Papillomavirus induces both lytic and proliferative changes in host keratinocytes
- Regression may confer immunity
TYPICAL CLINICAL FINDINGS:
- Large lesions may interfere with vision, respiration, food intake, or locomotion
- Often spontaneous regression within two months
TYPICAL GROSS FINDINGS:
- Raised, firm, warty, or smooth; nodules or plaques
- Solitary or multiple
- Up to 20 cm in diameter
- Usually found on the face, neck, shoulders, and legs
- On cut surface, there is a dense, white, fibrotic core with a rim of variably thick epidermis; hyperpigmentation (+/-)
- Large lesions may be pedunculated, with central necrosis, surface ulceration or opportunistic bacterial infections
- Deeper tissues are rarely invaded
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Predominance of dermal proliferation with the presence of acanthosis and hyperkeratosis with down growth of rete ridges in the epidermis (i.e. proliferating epidermal and dermal components)
- Stellate or spindle shaped hypertrophied fibroblasts in dermis separated by thick haphazard whorls and fascicles of dense collagenous connective tissue (contrast with granulation tissue)
- Epidermis is variably hyperplastic, hyperkeratotic, and hyperpigmented
- Mitoses are rare
- Sparse vasculature at center of tumor
- Larger masses may have necrohemorrhagic degeneration and cutaneous ulceration
- In long-standing tumors, cells have smaller, denser nuclei, and palisade perpendicular to the skin
- Icosahedral, 50-55 nm diameter, non-enveloped virions are present in nuclei of keratinocytes
ADDITIONAL DIAGNOSTIC TESTS:
- Viral antigen can be demonstrated by immunofluorescence or immunohistochemistry, in fresh and formalin fixed tissues, respectively
- in situ DNA hybridization and PCR
- Squamous cell carcinoma
- Papillomavirus-induced tumors:
- Classic examples of fibropapillomas in other species include bovine fibropapilloma, equine sarcoid and feline sarcoid / fibropapilloma
- Cattle: BPV-1, 2, 5 (cutaneous fibropapilloma); BPV-3, 6 (cutaneous papilloma); BPV-4 (papilloma of the alimentary tract and urinary bladder)
- Rabbit: Rabbit fibroma virus (Shope fibroma); papovavirus (Shope papilloma); rabbit oral papillomavirus (oral papilloma)
- Sheep: OPV-1 (fibropapilloma)
- Canine: COPV (cutaneous and oral papilloma)
- Equine: BPV-1, 2 (equine sarcoid)
- Feline: Unclassified papilloma virus most similar to bovine papillomavirus (feline fibropapilloma)
- Cheville NF, Lehmkuhl, H. Cytopathology of viral diseases. In: Cheville, NF, ed. Ultrastructural Pathology: The Comparative Cellular Basis of Disease. 2nd ed. Danvers, MA: Wiley-Blackwell; 2009:343-347.
- Cosgrove GE, Satterfield LC, Nettles VF. Neoplasia. In: Davidson, WR, ed. Diseases and Parasites of White‑tailed Deer. 1st ed. Athens, GA: University of GA Press; 1981:62-71.
- Erdélyi K, Dencső L, Lehoczki R, et. al. Endemic papillomavirus infection of roe deer (Capreolus capreolus). Vet Microbiol. 2009;138(1-2):20-26.
- Mauldin EA, 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: Saunders Elsevier; 2016: 706-707.
- Sundberg JP, van Ranst M, Jenson AB. Papillomavirus infections. In: Williams ES, Barker IK, eds. Infectious Diseases of Wild Mammals. 3rd ed. Ames, IA: Iowa State University Press; 2001:223-231.
- Teifke JP, Kidney BA, Löhr CV, et. al. Detection of papillomavirus-DNA in mesenchymal tumour cells and not in the hyperplastic epithelium of feline sarcoids. Vet Dermatol. 2003;14(1):47-56.
- von Bomhard W, Goldschmidt MH, Shofer FS, et. al. Cutaneous neoplasms in pet rabbits: A retrospective study. Vet Pathol. 2007;44(5):579-588.