A case of angiokeratoma

Angiokeratoma is described by various authors as a rare variant of the hemangioma in the dog, characterized by a vascular component, like all types of vascular neoplasms, but also by an epithelial component. A case of angiokeratoma is described in a male 8-year-old dog. The tumor was located in heavily pigmented skin on the anterior surface of the front limb and not in the more usual previously described locations, eyelid and conjunctiva. Microscopic examination revealed a well-circumscribed mass with irregular hyperplasia of the epidermis and dilated vascular spaces filled with blood in the superficial dermis.     

Lymphangiosarcoma in the nictitating membrane of a horse

A 15-year-old Haflinger gelding presented with a mass in the left nictitating membrane. Two biopsies and the excised nictitating membrane were taken at different time points as a result of reoccurrence of the mass and submitted for histopathologic evaluation. The horse was euthanized as a result of poor prognosis following the reoccurrence of the mass after surgical removal. Histologically, the mass consisted of dilated, thin-walled vascular clefts and channels, lined by flattened to cuboidal endothelial cells with moderate cellular pleomorphism. There was up to 1 mitotic figure per high power field. The channels were empty or contained few erythrocytes. In the collagen-rich stroma, few lymphocytes, focal follicular lymphoid aggregations, and marked lymphangiectasia were observed. Immunohistochemically, the neoplastic cells stained positive for vimentin and partially positive for factor VIII-related antigen. Ultrastructural analysis revealed discontinuous endothelial lining vascular channels that partially lacked a basal membrane. Based on the histopathologic, immunohistochemical, and ultrastructural features lymphangiosarcoma was diagnosed.     

Spontaneous cholangiofibrosis adjacent to a dilated common bile duct with intestinal metaplasia in a Royal College of Surgeons rat

A 130-week-old male Royal College of Surgeons rat kept as a non-treated animal in a long-term animal study presented with a mass in the hepatic portal region that adhered to a dilated common bile duct and the duodenum. Histopathologically, the solitary mass showed expansive growth with no apparent compression and continued to dilate the common bile duct, which had a hyperplastic epithelium with intestinal metaplasia. The mass mainly consisted of small to large dilated and/or tortuous ducts with abundant dense connective tissue and many inflammatory cells. The single-layer lining epithelium of the duct changed from cuboidal to columnar. Immunohistochemically, the lining cells were positive for cytokeratin 7, cytokeratin 19, and OV-6, which are bile duct markers. Based on the pathological characteristics, the rat was diagnosed as spontaneous cholangiofibrosis adjacent to a dilated common bile duct with intestinal metaplasia.     

Amplification of papillomaviral DNA sequences from a high proportion of feline cutaneous in situ and invasive squamous cell carcinomas using a nested polymerase chain reaction

Squamous cell carcinomas (SCCs) are common skin tumours of cats. Previous studies have suggested that papillomaviral (PV) DNA is detectible within some feline SCCs. A PV DNA sequence has been previously amplified from five feline bowenoid in situ carcinomas (BISCs). Primers specific for this sequence were used in a nested polymerase chain reaction to compare PV detection rates in SCCs to rates within non-SCC skin lesions. Papillomaviral DNA was amplified from 20 of 20 BISC, 17 of 20 invasive SCC and 3 of 17 non-SCC controls. The rate of PV amplification from feline cutaneous SCCs was significantly higher than from non-SCC lesions. These results confirm that feline cutaneous SCCs are associated with PV infection. In humans, there is evidence that PVs promote SCC development within sun-exposed skin. The demonstrated association between PVs and feline cutaneous SCCs suggests, but does not prove, that PVs may also promote feline SCC development. If PVs are oncogenic in cats, prevention of PV infection may reduce feline cutaneous SCC development. To the authors' knowledge, this is the first time that PV DNA has been amplified from a non-SCC sample of feline skin.     

Infrequent detection of papillomaviral DNA within canine cutaneous squamous cell carcinomas, haemangiosarcomas and healthy skin on the ventrum of dogs

Background – Canine squamous cell carcinomas (SCCs) most frequently develop on the ventral abdomen and are thought to be caused by ultraviolet (UV) light. Papillomaviruses (PVs) have been associated with cutaneous SCCs in multiple species, including dogs. Hypothesis – That PVs act as cofactors in canine UV‐induced SCCs. Animals – The study was performed on skin from the ventrum of 60 dogs. These samples included 20 SCCs, 20 haemangiosarcomas and 20 samples of clinically normal skin. Two canine viral plaques were included as positive controls for PV. Methods – PCR was used to amplify PV DNA from all samples. Primers used included two sets of consensus primers and two sets of primers that were designed specifically to amplify PV DNA sequences detected in the viral plaques. Results – The MY09/11 consensus primers amplified PV DNA from both viral plaques. One plaque contained a DNA sequence (CfPV‐JM) that had been previously reported from a dog with multiple cutaneous SCCs. The other plaque contained a previously unreported PV DNA sequence. No PV DNA was amplified by either consensus primer from any of the ventrum skin samples. Primers designed specifically to amplify the CfPV‐JM sequence amplified DNA from one SCC, but no other sample. No PV DNA was amplified using the other specific PCR primer set. Conclusions and clinical importance – These results do not support a significant role for PVs in SCC development from the ventrum of dogs. However, they contribute another PV sequence to the list of PVs that have been associated with viral plaque development in dogs.     

Amplification of three different papillomaviral DNA sequences from a cat with viral plaques

A 3‐year‐old cat from New Zealand developed three small raised non‐ulcerated plaques on the face. Serology detected antibodies against feline immunodeficiency virus (FIV). Histology of the plaque revealed epidermal hyperplasia with keratinocytes either distended with large blue‐grey cytoplasmic bodies or with shrunken nuclei surrounded by a clear halo. Papillomavirus (PV) antigen was detected immunohistochemically and feline viral plaque was diagnosed. Swabs were taken of both lesional and non‐lesional skin, and polymerase chain reactions were used to detect PV DNA. Three different PV DNA sequences were amplified, one from a Felis domesticus PV type 1 (FdPV‐1) previously amplified from a feline viral plaque, a second (FdPV‐JM) previously amplified from feline cutaneous squamous cell carcinomas, and a third FdPV‐MY that was not reported previously. All three sequences were amplified from swabs of both lesional and non‐lesional skin. These results extend the geographical range of FdPV‐1 outside North America and also demonstrate the ability of FdPV‐1 to asymptomatically infect feline skin. However, the detection of multiple PV sequences within both lesional and non‐lesional samples makes it difficult to determine whether or not any of the PVs caused feline viral plaque development in this cat. This is the first time PV DNA has been detected in a feline skin swab sample. Additionally, it is the first report of multiple PVs being detected in a single sample from a cat. This may suggest that FIV infection predisposes cats to cutaneous PV infection.     

Detection of novel papillomaviruslike sequences in paraffin-embedded specimens of invasive and in situ squamous cell carcinomas from cats

OBJECTIVE: To detect and partially characterize papillomavirus (PV) DNA in squamous cell carcinoma (SCC) tumor specimens from cats. SAMPLE POPULATION: 54 formalin-fixed paraffinembedded skin biopsy specimens were examined. Specimens originated from Bowenoid in situ SCC (BISC; n = 21), invasive SCC (22), and skin affected by miscellaneous nonneoplastic conditions (11). PROCEDURES: Samples from each tissue block underwent DNA extraction after deparaffinization, and PCR assays were performed. Two sets of primers derived from PV E1 were used. The first set of primers was designed for the narrow-range PCR assay and was able to generate amplification products of feline PV (FePV), canine oral PV, or closely related PVs. The second set of primers was selected for the broad-range PCR assay because of its ability to amplify DNA from 64 human PVs. Sequence analysis of each amplified DNA was performed. RESULTS: 1 of the 21 specimens of BISC was positive for PV DNA on the basis of narrow-range PCR assay results, whereas all the other specimens (BISC, invasive SCC, and controls) had negative results for PV DNA. In contrast, 5 of 21 BISC specimens and 4 of 22 invasive SCC specimens were positive for PV DNA on the basis of broad-range PCR assay results. Sequence analysis revealed that only 1 specimen was infected by a virus closely related to classic FePV. In the 8 other specimens positive for PV DNA, DNA of unknown PVs was uncovered. CONCLUSIONS AND CLINICAL RELEVANCE: Bowenoid in situ SCC and invasive SCC of cats may be associated with PVs of genetic diversity.     

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

Although papillomaviral (PV) DNA is frequently present in feline cutaneous squamous cell carcinomas (SCCs), a causative association cannot be proven. Oncogenic human PVs cause neoplastic transformation by inhibiting retinoblastoma (pRb) and p53 activity. Therefore, absence of pRb and p53 immunostaining, along with increased p16 immunostaining, indicates a PV cause in some human SCCs. If PVs cause cutaneous feline SCCs, it was hypothesized that a similar immunohistochemistry profile, along with PV DNA, would be detectable. This was investigated using 5 feline viral plaques, 10 Bowenoid in situ carcinomas, 19 SCCs from ultraviolet-exposed (UV-exposed) skin, and 11 SCCs from UV-protected skin. Papillomaviral DNA was amplified by polymerase chain reaction from 30 of 45 lesions. Reduced pRb immunostaining was present in 26 of 45; increased p16 immunostaining was in 30; and p53 immunostaining was in 19. Both reduced pRb immunostaining and increased p16 immunostaining were more frequent in lesions containing PV DNA. In contrast, no association was observed between p53 immunostaining and the presence of PV DNA. SCCs from UV-protected skin more frequently contained PV DNA, reduced pRb, and increased p16 than UV-exposed SCCs. UV exposure was not associated with p53 immunostaining within the SCCs. These results suggest that feline PVs alter cell regulation by degrading pRb. Unlike oncogenic human PVs, there was no evidence that feline PVs degrade p53. These results provide further evidence that PVs may cause feline cutaneous SCCs, especially those in UV-protected skin, and they suggest a possible mechanism of this oncogenic action.     

Detection of papillomavirus-DNA in mesenchymal tumour cells and not in the hyperplastic epithelium of feline sarcoids

Abstract We examined 12 formalin-fixed paraffin-embedded feline skin tumours which had the histopathological features of fibropapillomas for the presence of papillomavirus (PV) DNA using touchdown polymerase chain recation (PCR), DNA sequencing and nonradioactive in situ hybridization. Nine of the tumours contained a 102-bp PCR product demonstrated using consensus PV primers that amplify a portion of the L1 gene. The nucleotide sequences are closely related, but not identical to that of ovine PV type 2, rabbit oral PV and reindeer PV. The deduced amino acid sequences had strong homologies with the major capsid protein L1 of deer PV, bovine papillomavirus (BPV) 1 and BPV 2, and European elk PV. Although PV antigens were not detected in any of the tumours by immunohistochemistry, PV DNA was demonstrated in individual mesenchymal cells or cell nests of 4/12 tumours by in situ hybridization. A nonproductive infection of mesenchymal fibroblast-like tumour cells with a papillomavirus would explain the lack of PV antigen expression and the absence of PV DNA in the hyperplastic epithelium. Because these tumours and their pathogenesis are similar to equine sarcoids, we suggest that they should be reclassified as 'feline sarcoids' instead of fibropapillomas.     

Multiple feather follicle cysts in a Moroseta hen (Gallus gallus)

An 8-month-old white feathered, black skinned Moroseta hen was presented for examination because of numerous 2 mm- to 30 mm-diameter irregularly shaped, hard nodules in the skin of the head, wings, back, and abdomen. The nodules were confined to the skin and did not involve subcutaneous tissues. Nodules consisted of dilated feather follicles packed with a caseous tan-to-pale-yellow material admixed with feather remnants. Histologically, affected feather follicles were markedly dilated and filled with laminated keratin debris. Necrosis of the epidermis and perifollicular lymphocyte infiltration was also present. Bacteriologic investigation of internal organs was negative, while secondary bacteria, Proteus spp. and Bacillus spp., were isolated from skin nodules. A concomitant lice infestation of Menopon spp., as well as leg mange caused by Cnemidocoptes spp., were also present. These bacterial isolates and parasites were not related to the disease condition. The condition observed was differentiated from benign feather follicle tumors, and a diagnosis of multiple feather follicle cysts was made. In addition, a breed predisposition was hypothesized.     

Upregulation of c-Myc may contribute to the pathogenesis of canine pemphigus vulgaris

The pathomechanism in human pemphigus vulgaris (PV) has recently been described to rely on generalized c-Myc upregulation in skin and oral mucosa followed by hyperproliferation. Here we assessed whether dogs suffering from PV present the same pathological changes as described for human patients with PV. Using immunofluorescence analysis on patients' biopsy samples, we observed marked nuclear c-Myc accumulation in all layers of the epidermis and oral mucosa in all (3/3) dogs analysed. In addition, c-Myc upregulation was accompanied by an increased number of proliferating Ki67-positive cells. These molecular changes were further paralleled by deregulated expression of wound healing and terminal differentiation markers as observed in human PV. Together these findings suggest a common pathomechanism for both species which is of particular relevance in the light of the recently discussed novel therapeutic strategies aiming at targeting PV antibody-induced signalling cascades.     

Amplification of feline sarcoid‐associated papillomavirus DNA sequences from bovine skin

Feline sarcoids are uncommon dermal neoplasms that are thought to be caused by papillomaviral (PV) infection. Feline sarcoid‐associated PV (FeSarPV) has been consistently detected in sarcoids from North American and New Zealand cats but has not been detected within any other feline sample. This suggests that feline sarcoids may develop due to cross‐species infection by a PV from an unidentified reservoir host. While there is some epidemiological evidence to suggest that cattle are the reservoir host of FeSarPV, this PV has never been identified within any bovine sample. In this study both consensus PCR primers and primers specific to FeSarPV were used to investigate the presence of PV DNA within five fibropapillomas and 18 samples of inflammatory skin disease from cattle. Consensus primers amplified bovine PV‐2 DNA from four fibropapillomas, but none of the dermatitis samples. However, specific primers amplified FeSarPV DNA from four fibropapillomas and five inflammatory skin lesions. To the best of our knowledge this is the first time that FeSarPV has been detected within any sample other than a feline sarcoid. The ability of FeSarPV to asymptomatically infect bovine skin suggests that cattle are the reservoir host of this PV and feline sarcoids could be the result of cross‐species infection of a dead‐end host by a bovine PV.     

Detection of novel papillomaviruses in canine mucosal, cutaneous and in situ squamous cell carcinomas

Papillomavirus (PV) DNA is frequently uncovered in samples of human skin squamous cell carcinomas (SCC). However, the role of these viruses in the development of such cancers in canine species remains controversial. While approximately 100 human PVs are known, only one single canine oral PV (COPV) has been identified and studied extensively. Therefore, we applied a narrow-range polymerase chain reaction (PCR) suitable for the detection of classical canine and feline PVs, as well as a broad-range PCR, which has been used for the detection of various novel PVs in humans, in order to analyse 42 paraffin-embedded samples, representing three different forms of canine SCCs. Ten samples of skin tissues with various non-neoplastic conditions served as controls. While none of the negative controls reacted positively, PV DNA was discovered in 21% of the tested SCC samples. Interestingly, the classical COPV was amplified from only one sample, while the other positive cases were associated with a variety of thus far unknown PVs. This study suggests that a fraction of canine SCC is infected with PVs and that a genetic variety of canine PVs exists. Therefore, these results will facilitate the future study of the role of PVs in the development of canine skin cancers.     

Two rare cutaneous neoplasms in horses: apocrine gland adenocarcinoma and carcinosarcoma

Two rare equine cutaneous neoplasms, an apocrine gland adenocarcinoma and a carcinosarcoma were diagnosed in a 17-year-old pony and a 14-year-old mare, respectively. The apocrine gland adenocarcinoma was present on the prepuce. Histologically, papillary projections of low cuboidal to columnar epithelial cells were generally well differentiated, and surrounded dilated acini. Stromal invasion was present, but vascular and lymphatic invasion was not seen. The carcinosarcoma was present in the right flank of the mare. Two discrete cell populations were characterized histologically. One portion of the mass was composed of elongated, loosely arranged mesenchymatous cells; the second population consisted of dense sheets of pleomorphic, basophilic cells forming irregular acini.     

Post-traumatic peripheral arteriovenous fistula manifesting as digital haemorrhages in a cat: diagnosis with contrast-enhanced 3D CT imaging

Arteriovenous fistulae (AVF) are defined as congenital or acquired abnormal direct communications between an artery and a vein leading to abnormal blood circulation. This report describes an unusual manifestation of acquired peripheral AVF in a cat for which the diagnosis was confirmed by computed tomographic (CT) imaging and three-dimensional (3D) reconstruction. A 10-year-old female spayed domestic shorthaired cat was presented with a 2-month history of nonhealing, crusting, erosive and ulcerative skin lesions on the dorsal right forepaw. Severe chewing and biting, but not lameness, had been reported. Systemic abnormalities were not noted. Histopathology revealed increased numbers of thin-walled and slightly grouped vascular profiles in the superficial and mid-dermis, which were often markedly dilated and partially obscured by prominent hyaline deposits. There were a few pyknotic nuclear fragments and haemorrhages in vascular walls as well as multifocal luminal thrombosis with or without recanalization. Differential diagnoses included progressive angiomatosis with trauma or AVF with secondary regional venous hypertension. Computed tomographic images were acquired using a 16-slice Siemens Somotom Sensation CT scanner, and 3D images were created using the Voxar 3D software. Image reconstruction revealed tortuous aberrant vasculature on the medial aspect of the radius and around the carpus compared to normal vascularization on the contralateral limb. These changes were suggestive of the diagnosis of acquired peripheral AVF. The differential diagnosis for localized, nonhealing, haemorrhagic, crusted, erosive or ulcerative distal extremity skin lesions in cats should include acquired AVF, and diagnosis may be confirmed with contrast-enhanced CT imaging.     

Papillomaviral DNA and increased p16CDKN2A protein are frequently present within feline cutaneous squamous cell carcinomas in ultraviolet-protected skin

Squamous cell carcinomas (SCCs) are common feline skin tumours. While exposure to ultraviolet (UV) light causes some SCCs, a subset develop in UV-protected skin. In cats, papillomaviruses (PVs) cause viral plaques and Bowenoid in situ carcinomas (BISCs). As both may progress to SCC, it was hypothesized that SCCs in UV-protected skin may represent neoplastic transformation of a PV-induced lesion. To investigate this hypothesis, PCR was used to amplify PV DNA from 25 UV-protected and 45 UV-exposed SCCs. Oncogenic human PVs cause neoplasia by mechanisms that also increase p16(CDKN2A) protein (p16). As increased p16 is present in feline viral plaques and BISCs, immunohistochemistry was used to detect p16 within the SCCs. Papillomaviral DNA was amplified from 76% of UV-protected SCCs, but only 42% of UV-exposed SCCs. Increased p16 was present in 84% of UV-protected SCCs, but only 40% of UV-exposed SCCs. The more frequent detection of PV DNA and increased p16 within UV-protected SCCs supports the hypothesis that some develop from a PV-induced plaque or BISC. Felis domesticus PV-2 is thought to cause viral plaques and BISCs. This PV was detected most frequently within the UV-protected SCCs, supporting development from a PV-induced lesion. Increased p16 and PV DNA were less frequent within UV-exposed SCCs, presumably because these developed from actinic keratosis rather than a PV-induced lesion. The results support the hypothesis that some feline cutaneous SCCs are caused by PV infection and suggest that PVs may cause neoplasia by mechanisms that also increase p16.     

IgG autoantibodies directed against desmoglein 3 cause dissociation of keratinocytes in canine pemphigus vulgaris and paraneoplastic pemphigus

Pemphigus is a group of autoimmune blistering diseases of the skin and mucous membranes. In human patients with pemphigus vulgaris (PV) and paraneoplastic pemphigus (PNP), IgG autoantibodies against desmoglein (Dsg) 3 and Dsg1 play pathogenic roles in blister formation. In contrast, the target for IgG autoantibodies that induce keratinocyte dissociation has not been elucidated in canine pemphigus. The aim of the present study was to determine whether anti-Dsg IgG autoantibodies are present and disrupt the cell-cell adhesion of keratinocytes in canine PV and PNP. The extracellular domains of canine Dsg3 were recognized by IgG in 3/5 (60%) canine PV sera tested. IgG against the extracellular domains of canine Dsg1 was detected exclusively in two dogs that had PV with the mucocutaneous phenotype. In addition, anti-Dsg3 IgG was identified in canine PNP serum. Furthermore, incubation of normal human keratinocytes (NHK) with mucocutaneous canine PV serum and canine PNP serum resulted in dissociation of the NHK sheets, whereas the removal of anti-Dsg3 IgG from these canine sera blocked this dissociation. The present study indicates for the first time that circulating anti-Dsg3 IgG antibodies capable of dissociating keratinocytes are present in dogs with PV and PNP.     

Novel betapapillomavirus associated with hand and foot papillomas in a cynomolgus macaque

Betapapillomavirus is a genus of papillomaviruses (PVs) commonly found in human skin and associated with both benign and malignant skin lesions. Only 2 previous beta-PVs have been fully characterized in nonhuman species. This report describes a novel beta-PV, named Macaca fascicularis PV type 2 (MfPV2), isolated from exophytic skin papillomas on the hands and feet of a 2-year-old male cynomolgus monkey (M. fascicularis). On histology the papillomas were composed of diffusely thickened epidermis with superficial foci of cytomegaly, cytoplasmic pallor, marginalized chromatin, and rare eosinophilic intranuclear inclusion bodies. Positive immunostaining for p16 and the proliferation marker Ki67 was present multifocally within affected epidermis, most prominently within basal-type cells. Complete sequence identity (100%) was noted between PV genomes fully sequenced from hand and foot lesions. The MfPV2 genome was 7632 base pairs in length and included putative open reading frames (ORFs) for E1, E2, E4, E6, E7, L1, and L2 genes, similar to other PVs. The closest relatives to MfPV2 based on the L1 ORF sequence were all beta-PVs. These included human PV (HPV) 9, HPV115, HPV76, HPV75, and MfPV1 (60-70% pairwise identity for all), the latter of which was also isolated from hand and foot papillomas in a cynomolgus macaque. Phylogenetic analysis placed MfPV2 in a new species group (beta-6), distinct from HPVs (beta-1 to beta-5) and MfPV1 (beta-1). These findings characterize a new nonhuman beta-PV and provide additional support for the idea that tissue tropism among ancestral primate PVs developed prior to divergence of certain Old World primate lineages.     

Oesophageal impaction in a Canada goose (Branta canadensis)

An oesophageal impaction, consisting of plant material and nylon fishing line, and alimentary parasitism were diagnosed and treated in a Canada goose. At presentation the bird was non-ambulatory with flaccid neck muscles, lethargic, emaciated, dehydrated and had watery brown to green faeces. Palpation of the neck revealed a solid tubular mass ventrally in the mid-cervical region with gritty material cranial to it. Radiographs disclosed an oesophageal mass containing seed or grit-like radio-opaque material, and dilated cranial oesophagus containing radio-opaque material. Laboratory investigations revealed non-regenerative anaemia, heterophilia, lymphopenia, hypoproteinaemia, and many strongyle eggs in faeces. Treatment included supportive therapy, oesophageal gavage, oesophagotomy and drug therapy. The bird recovered and was released 27 days after initial presentation.     

Cutaneous vascular malformation in a guinea pig (Cavia porcellus)

Abstract   A skin lesion classified as a vascular malformation is reported in a young-adult, female guinea pig. The physical examination revealed a 3 × 2-cm irregularly shaped violaceous plaque located on the left caudal flank. The surface of the plaque was ulcerated and bled intermittently, resulting in fatal blood loss. On histology the mass consisted of variably sized vascular spaces filled with red blood cells and variable amounts of extramedullary haematopoietic cells, lined by well-differentiated endothelial cells often surrounded by one layer of spindle-shaped cells. Based on immunohistochemistry, the spindle cell population was confirmed to be smooth muscle cells and no proliferation of endothelial cells was found with the Ki67 proliferation marker. Histological and immunohistochemical findings were consistent with a vascular malformation. Classification of vascular malformations and potential treatments are discussed. To the authors' knowledge, this is the first reported case of a cutaneous vascular lesion in a guinea pig.