Ameloblastic fibro-odontosarcoma with mandibular bone invasion and regional lymph node metastasis in a cat: case report.

Odontogenic tumours are uncommon neoplasms in domestic animals, mostly solitary and locally infiltrative, but rarely metastatic. We report the case of a 13-year-old neutered male cat presented with a mandibular gingival neoformation. A computed tomography scan revealed an irregular neoformation with marked post-contrast enhancement, associated with lysis of the incisive bone and mandibular symphysis. Histologically, the oral mucosa and mandibular bone were infiltrated by a neoplasm consisting of a mixed population of odontogenic epithelium admixed with bundles of odontogenic ectomesenchyme, multifocally associated with hard tissue deposition. A spindloid cell component had metastasized to the right mandibular lymph node. The epithelial component was immunoreactive for cytokeratins (CK) 5/6, CK 14, pancytokeratin (CK AE1/AE3) and p63; the ectomesenchymal component was vimentin positive. A final diagnosis of ameloblastic fibro-odontosarcoma with bone invasion and lymph node metastasis was made. The findings indicate the metastatic potential of this rare tumour.

Oral fibroepithelial polyps ("chewing granulomas") in 21 dogs: Histomorphology, immunohistochemical characterization, and clinical outcome.

Oral fibroepithelial polyps (FEPs) are common, benign, nonneoplastic lesions in humans that often develop slowly in sites of local irritation or trauma. This study analyzed 23 oral fibroepithelial polypoid lesions retrieved from 21 dogs (2014-2021). All lesions were pedunculated with usually an irregular/cauliflower-like or rarely smooth surface. FEPs most commonly arose under or lateral to the tongue; other sites included the labial and gingival mucosa, soft palate, and hard palate. All the lesions were characterized by a thick fibrovascular stalk consisting of bundles of fibrocytes and fibroblasts embedded in a collagenous matrix rich in blood vessels. The surface squamous epithelium, when evaluable, was hyperplastic (22/22; 100%) with frequent parakeratotic hyperkeratosis (12/22; 54.5%). Ulceration of variable extent was observed in 13/23 cases (56.5%). Inflammation was associated with 18/23 cases (78.3%), and was mostly lymphoplasmacytic. The connective tissue was consistently immunoreactive for vimentin and generally negative for smooth muscle actin and desmin. All FEPs in cases with available clinical outcome data did not recur after surgical excision. The presence of chronic inflammation and ulceration suggests a causative role of chronic irritation in the pathogenesis of canine oral FEPs. FEPs should be included among the differential diagnoses of proliferative lesions of the oral cavity in dogs.

Molecular and Immunohistochemical Expression of LTA4H and FXR1 in Canine Oral Melanoma.

Oral melanoma is a common canine tumor whose prognosis is considered ominous, but poorly predicted by histology alone. In the present study the gene and protein expression of Leukotriene A4 hydrolase (LTA4H) and Fragile-X-mental retardation-related protein1 (FXR1), both reported as related to metastatic potential in different tumors, were investigated in canine oral melanoma. The main aim of the study was to confirm and quantify the presence of LTA4H and FXR1 genes and protein in oral melanomas. A secondary aim was to investigate their association with histologic prognostic criteria (mitotic count, Ki-67 index). Formalin-fixed-paraffin-embedded canine oral melanomas (36) were collected and histopathological evaluation carried out. Immunolabelling for LTA4H and FXR1 and Ki-67 were performed. RT-PCR evaluated LTA4H and FXR1 gene expressions. Histologically, most tumors were epithelioid cell melanomas (19/36) and were amelanotic, mildly or moderately pigmented (5, 12 and 13/36 respectively), only 6 were highly pigmented. Mitotic count ranged 1-106, Ki-67 index ranged 4.5-52.3. Thirty-two (32/32) melanomas immunolabelled for LTA4H and 33/34 for FXR1. RT-PCR values ranged 0.76-5.11 ΔCt for LTA4H and 0.22-6.24 ΔCt for FXR1. Molecular and immunohistochemical expression of both LTA4H and FXR1 did not statically correlate with mitotic count or Ki-67 index. The present study demonstrates LTA4H and FXR1 gene and protein in canine oral melanoma, however their expression is apparently unrelated to histopathologic prognostic criteria. Although LTA4H and FXR1 seem unrelated to tumor behavior, their extensive expression in the present cohort of cases suggest that they may play a role in canine oral melanoma oncogenesis.

Epithelial lacrimal gland tumors in dogs and cats: Is the human WHO classification appropriate for animals?

Lacrimal gland tumors (LGTs) in dogs and cats are rare neoplasms that can affect either the nictitans (NLG) or the main lacrimal gland (MLG). A consistent classification scheme for canine and feline LGTs is lacking; however, the importance of a classification scheme for LGTs has been emphasized in the human literature, and an update to the World Health Organization (WHO) classification has recently been published. The aim of this study was to investigate the occurrence of different subtypes of canine and feline LGTs in accordance with the human WHO classification system. Epithelial LGTs (n = 46 tumors; 38 dogs, 8 cats) were reviewed and immunophenotyping for p63, CK14, SMA, calponin, CKAE1/AE3, and CK19 was performed. Consistent with previous literature reports, lacrimal carcinomas outnumbered adenomas in dogs and cats. Based on the WHO classification of human LGTs, the most common subtypes identified in dogs were pleomorphic, ductal, adenoid cystic, and epithelial-myoepithelial carcinoma. In cats, a lower number of subtypes was observed, and adenocarcinoma "not otherwise specified" (NOS) was the most frequent diagnosis. An uncommon case of feline epithelial-myoepithelial carcinoma was also observed. The application of the human WHO-LGT classification scheme to canine and feline tumors increased the diversity of diagnoses and allowed for the identification of numerous subtypes. Further studies to identify possible correlations between pathological subtypes and prognosis are warranted.

Immunohistochemical Expression of FXR1 in Canine Normal Tissues and Melanomas.

Fragile X mental retardation-related protein 1 (FXR1) is a cytoplasmic RNA-binding protein highly conserved among vertebrates. It has been studied for its role in muscle development, inflammation, and tumorigenesis, being related, for example, to metastasizing behavior in human and canine uveal melanoma. Anti-FXR1 antibodies have never been validated in the canine species. To investigate FXR1 expression in canine melanocytic tumors, the present study tested two commercially available polyclonal anti-human FXR1 antibodies, raised in goat and rabbit, respectively. The cross-reactivity of the anti-FXR1 antibodies was assessed by Western blot analysis, and the protein was localized by IHC in a set of normal canine tissues and in canine melanocytic tumors (10 uveal and 10 oral). Western blot results demonstrated that the antibody raised in rabbit specifically recognized the canine FXR1, while the antibody raised in goat did not cross-react with this canine protein. FXR1 protein was immunodetected using rabbit anti-FXR1 antibody, in canine normal tissues with different levels of intensity and distribution. It was also detected in 10/10 uveal and 9/10 oral melanocytic tumors. The present study validated for the first time the use of anti-FXR1 antibody in dogs and highlighted different FXR1 protein expression in canine melanocytic tumors, the significance of which is undergoing further investigations.

Fibrosarcoma of the eyelid in two sibling Czech wolfdogs.

Most canine tumors of the eyelid are tumors generally encountered in the skin. They are most commonly of epithelial origin and benign. In this report, we describe the cases of two sibling Czech wolfdogs presented, one year apart, with a subcutaneous mass involving the left eyelid. Both lesions were histologically consistent with a diagnosis of subcutaneous fibrosarcoma. Immunohistochemical analyses of the tumors revealed a mild positivity for vimentin and negativity for GFAP, desmin, αSMA, myoglobin, S100, PNL2 and calponin, excluding all differential diagnosis (i.e. peripheral nerve sheath tumor, melanoma, perivascular sarcoma, myofibroblastic sarcoma, rhabdomyosarcoma). To the best of authors' knowledge, this is the first report of canine eyelid fibrosarcoma. Since this rare tumor has been observed in two full siblings, we could speculate the existence of some genetic predisposition to sarcoma, however the present data did not allow any definite conclusion on the etiopathogenesis or genetic basis of these tumors.

Squamous Cell Carcinoma of the Oropharynx and Esophagus with Pulmonary Metastasis in a Backyard Laying Hen.

A backyard laying hen exhibiting muscular atrophy, dyspnea, and absence of egg production was analyzed for diagnostic insights. Gross findings revealed the presence of a large ulcerated mass with irregular edges involving the caudal part of the oropharynx and the cranial part of the esophagus, occluding the lumen of the esophagus and compressing the trachea. Small nodular lesions were detected also in the lungs. Histologically, both esophageal and pulmonary masses were characterized by nests of pleomorphic epithelial cells with squamous differentiation. The diagnosis was of squamous cell carcinoma of the esophagus with the uncommon feature of pulmonary metastasis.