Concomitant melanoma and keratoma affecting the equine digit: clinical, pathological, and long-term follow-up findings.

BACKGROUND: This case report details a long-term follow-up of a hoof melanoma with dermo-epidermal activity (resembling Spreading Superficial Melanoma (SSM)) in a bay horse with a history of a right front hoof keratoma. Melanomas involving the horse's foot are seldom reported and usually diagnosed as anaplastic melanomas based on signalment and post-mortem examination. The clinical-pathological characteristics of the foot melanoma in this bay horse are consistent with SSM-like described in humans, which is considered an intermediate malignant tumour attending their biological behaviour. However, a definitive diagnosis is limited by the single case and the lack of references in horses. CASE PRESENTATION: A 12-year-old bay Andalusian gelding underwent keratoma removal on the lateral aspect of the hoof wall. A partial resection of the hoof wall was performed for this purpose. Additionally, a plaque-like, hyperkeratotic pigmented lesion, 2 × 2X0,4 cm in size, was observed at the lateral aspect of the coronary band and was also resected for histopathological examination. Microscopically, a melanocytic tumour, characterised by small nests of large polygonal or epithelioid cells infiltrating the basal and suprabasal epidermis, the dermo - epidermal junction, and the superficial dermis, was observed. The neoplastic cells exhibited large euchromatic nuclei, prominent nucleoli, moderate pleomorphism and 4 mitotic figures per 2,37mm2; variable amounts of dark granules (melanin) were present in the cytoplasm, as well as in numerous peritumoral macrophages. The immunophenotype of the tumour cells was PNL2 + + + , S100 + + , AE1/AE3-. A diagnosis of melanoma with dermo-epidermal junction and marked intraepidermal activity (consistent with superficial spreading melanoma) was made. A magnetic resonance imaging (MRI) performed, revealed no further invasion into surrounding structures. Treatment was based on surgical resection and multiple local chemotherapy sessions with cisplatin were applied. The biopsies obtained after treatment showed partial regression of the tumour and different stages of healing. After 26 months of follow-up, there was no signs of malignant spreading into surrounding structures including the pedal bone and distal metastasis but a dark - coloured area persists over the lateral aspect of the coronary band. CONCLUSIONS: This case presents a concomitant keratoma and melanoma with dermo - epidermal activity, resembling a spreading superficial melanoma. After a follow - up of 26 months the horse remains healthy and sound providing new information for clinicians and pathologists. Despite the poor prognosis associated with foot malignant melanocytic tumours, it is important that an early and accurate diagnosis is reached through different diagnostic modalities such as advanced imaging techniques and histopathology. Additionally, these findings demonstrate that the current classification and prognosis for equine foot melanomas are insufficient.

Equine intraocular melanocytic neoplasia.

Objective: To describe the clinical appearance, histopathology, and treatment of equine intraocular melanocytic neoplasia in adult horses. Animals and procedure: A retrospective review of medical records was conducted. Data recorded included signalment, ocular examination findings, physical examination findings, therapeutic interventions, and case outcomes. Histopathologic characteristics of enucleated globes were evaluated. A Student's t-test was used to evaluate differences in the interval from diagnosis to last known outcome between horses receiving therapeutic interventions and horses undergoing monitoring alone. Results: Of the 55 horses included, Arabian was the most common breed (15/55, 27%). Gray was the most common coat color (85%). Physical examination was completed for 75% of horses at time of diagnosis, and of those, 67% had cutaneous melanoma. The interval from diagnosis to last known outcome was not different (P = 0.312) between horses that underwent monitoring alone (median: 2.0 y) and those that received treatment (mean: 2.25 y). Conclusion: Equine intraocular melanocytic neoplasms are highly associated with cutaneous melanoma and gray coat color, and they are more prevalent than previously published reports suggest. Clinical relevance: A complete ophthalmic examination is indicated for all horses with cutaneous melanoma. Additional research into the timing and rationale for treatment of intraocular melanocytic neoplasia is necessary.

Néoplasie mélanocytaire intraoculaire équine. Objectif: Décrire l'aspect clinique, l'histopathologie et le traitement de la néoplasie mélanocytaire intraoculaire équine chez le cheval adulte. Animaux et procédure: Une étude rétrospective des dossiers médicaux a été réalisée. Les données enregistrées comprenaient le signalement, les résultats de l'examen oculaire, les résultats de l'examen physique, les interventions thérapeutiques et les résultats des cas. Les caractéristiques histopathologiques des globes énucléés ont été évaluées. Un test t de Student a été utilisé pour évaluer les différences dans l'intervalle entre le diagnostic et le dernier résultat connu entre les chevaux recevant des interventions thérapeutiques et les chevaux soumis à une surveillance seule. Résultats: Sur les 55 chevaux inclus, l'Arabe était la race la plus répandue (15/55, 27 %). Le gris était la couleur de robe la plus courante (85 %). L'examen physique a été réalisé pour 75 % des chevaux au moment du diagnostic, et parmi eux, 67 % présentaient un mélanome cutané. L'intervalle entre le diagnostic et le dernier résultat connu n'était pas différent (P = 0,312) entre les chevaux ayant subi une surveillance seule (médiane : 2,0 ans) et ceux ayant reçu un traitement (moyenne : 2,25 ans). Conclusion: Les néoplasmes mélanocytaires intraoculaires équins sont fortement associés au mélanome cutané et à la couleur du pelage gris, et ils sont plus fréquents que ne le suggèrent les rapports publiés précédemment. Pertinence clinique: Un examen ophtalmologique complet est indiqué pour tous les chevaux atteints de mélanome cutané. Des recherches supplémentaires sur la planification et la justification du traitement de la néoplasie mélanocytaire intraoculaire sont nécessaires.(Traduit par Dr Serge Messier).

Identification of mutations in canine oral mucosal melanomas by exome sequencing and comparison with human melanomas.

Oral mucosal melanomas (OMMs) are aggressive neoplasms commonly found in dogs but rare in humans. Utilizing whole exome sequencing (WES), which focuses on protein-coding regions to reveal mutation profiles, we conducted a comparative analysis of canine OMM and human melanomas. This study involved DNA extraction, exome enrichment, and sequencing from three canine OMM cell lines (CMGD-2, CMGD-5, TLM-1), five canine OMM frozen samples, a human OMM cell line (MEMO), and a human commercial skin melanoma cell line (SK-MEL-28). The sequencing and subsequent analysis of FASTQ files yielded final variant files, leading to the identification of mutations. Our findings revealed a total of 500 mutated genes in canine OMM, including significant ones such as EP300, FAT4, JAK3, LRP1B, NCOR1, and NOTCH1. Notably, 82 shared mutations were identified between human melanomas and canine OMM genomes. These mutations were categorized based on the gene functions. The identification of these mutations provides critical insights that can pave the way for the development of novel therapeutic strategies for both canine and human OMM, offering hope for more effective treatments in the future.

Clinicopathologic description of a cutaneous melanocytic tumor in a 1-year-old cat.

A feline cutaneous melanocytic tumor in a 1-year-old cat is reported. The cytologic, histologic, and immunohistochemical characteristics of the pediatric feline cutaneous melanocytoma are included. A solitary, black-colored nodule on the head was histologically diagnosed as the epithelioid type of melanocytoma. Immunohistochemically, the neoplastic melanocytes demonstrated immunoreactivity to the S100 and MelanA antibodies but not to the PNL2 antibody. Despite high mitotic counts (17/10HPFs) and a Ki67 index (33%) suggesting malignant melanoma, the patient exhibited a favorable 5-month outcome. The mitotic activity of the neoplastic cells may not provide a reliable prediction for feline melanocytic tumors.

Equine Melanoma Updates.

Melanomas are very common in older gray horses, with 80% of gray horses having at least 1 melanoma by 15 years of age. Historically considered a benign disease, it is now known that up to 66% of lesions will eventually metastasize. Melanomas may also cause local problems due to abscessation, ulceration, and interference with function of the affected areas. Treatment can be limited by size and location, but surgical resection, where possible, is likely to be the treatment of choice.

Dermal melanoma with plasmacytoid differentiation in a dog.

A 10-y-old spayed female Staffordshire Terrier dog was evaluated because of a cutaneous left ear base mass. Cytology revealed sheets of cells with anisocytosis and anisokaryosis, round-to-oval or plasmacytoid cytoplasm, and round, central, or eccentric nuclei; binucleate cells were present. Cytologic findings were consistent with a round cell tumor (plasmacytoma or agranular mast cell tumor), amelanotic melanoma, or anaplastic carcinoma. Histologically, neoplastic cells were polygonal to elongate, with round-to-oval nuclei and prominent nucleoli and arranged in sheets and nests on a fibrovascular stroma. Neoplastic cells with plasmacytoid morphology (round, glassy, eosinophilic cytoplasm with eccentric nuclei) were present in ~30% of the neoplasm. There were 18 mitoses in 2.37 mm2 (10 FN22/40× fields). Neoplastic cells had cytoplasmic immunolabeling for melan A and PNL2 and no immunolabeling for AE3/1 and MUM1, consistent with a dermal melanoma with plasmacytoid differentiation. The patient was re-evaluated ~1 mo after the first biopsy because of local recurrence of the original mass and new masses on the interscapular area and right elbow; these neoplasms were histologically identical to the original submission, plus scattered neoplastic cells in the new masses contained brown cytoplasmic pigment. The dog was euthanized because of swelling and hemorrhage of the tumors and right pelvic limb lameness. Our findings were consistent with a dermal melanoma with plasmacytoid features that were similar to human plasmacytoid melanoma, a rare variant of human melanoma that is diagnostically challenging as it may mimic a plasmacytoma.

An intronic copy number variation in Syntaxin 17 determines speed of greying and melanoma incidence in Grey horses.

The Greying with age phenotype in horses involves loss of hair pigmentation whereas skin pigmentation is not reduced, and a predisposition to melanoma. The causal mutation was initially reported as a duplication of a 4.6 kb intronic sequence in Syntaxin 17. The speed of greying varies considerably among Grey horses. Here we demonstrate the presence of two different Grey alleles, G2 carrying two tandem copies of the duplicated sequence and G3 carrying three. The latter is by far the most common allele, probably due to strong selection for the striking white phenotype. Our results reveal a remarkable dosage effect where the G3 allele is associated with fast greying and high incidence of melanoma whereas G2 is associated with slow greying and low incidence of melanoma. The copy number expansion transforms a weak enhancer to a strong melanocyte-specific enhancer that underlies hair greying (G2 and G3) and a drastically elevated risk of melanoma (G3 only). Our direct pedigree-based observation of the origin of a G2 allele from a G3 allele by copy number contraction demonstrates the dynamic evolution of this locus and provides the ultimate evidence for causality of the copy number variation of the 4.6 kb intronic sequence.

A Whole-Transcriptomic Analysis of Canine Oral Melanoma: A Chance to Disclose the Radiotherapy Effect and Outcome-Associated Gene Signature.

Oral melanoma (OM) is the most common malignant oral tumour among dogs and shares similarities with human mucosal melanoma (HMM), validating the role of canine species as an immunocompetent model for cancer research. In both humans and dogs, the prognosis is poor and radiotherapy (RT) represents a cornerstone in the management of this tumour, either as an adjuvant or a palliative treatment. In this study, by means of RNA-seq, the effect of RT weekly fractionated in 9 Gray (Gy), up to a total dose of 36 Gy (4 weeks), was evaluated in eight dogs affected by OM. Furthermore, possible transcriptomic differences in blood and biopsies that might be associated with a longer overall survival (OS) were investigated. The immune response, glycosylation, cell adhesion, and cell cycle were the most affected pathways by RT, while tumour microenvironment (TME) composition and canonical and non-canonical WNT pathways appeared to be modulated in association with OS. Taking these results as a whole, this study improved our understanding of the local and systemic effect of RT, reinforcing the pivotal role of anti-tumour immunity in the control of canine oral melanoma (COM).

Malignant skin neoplasms in goats in Sicily, Italy: clinical, virological and pathological investigations.

Neoplasms in small ruminants are considered uncommon and their reported incidence is variable. The aims of this investigation were to characterize malignant skin neoplasms in adult goats reared in Sicily, Italy, and to evaluate potential correlations between gross and histopathology features of the tumours and signalment, tumour location and/or viral infections. A total of 75 malignant skin masses were examined. In selected animals with perineal masses (n = 28) virological and serological investigations on tissues and blood were also conducted. According to the histological features, the lesions were classified as 67 squamous cell carcinomas (SCCs) (of which 65 were located in the perineum), six melanomas and two fibrosarcomas. In three cases, neoplasms at the base of the horn were associated with nasal polyps. Among the selected perineal SCCs, papillomaviruses (PVs), caprine herpesvirus 1 and parapoxvirus were not detected on polymerase chain reaction or on serological examination. However, further investigation on a larger sample size is required to evaluate the potential role of PVs in the pathogenesis of skin tumours in goats.

Pilot study to evaluate isolation by size of circulating tumour cells in canine oral melanoma.

Liquid biopsy for circulating tumour cell (CTC) detection is generally unexplored in veterinary medicine. Dogs with highly aggressive and heterogeneous tumours, such as oral malignant melanoma (OMM), could benefit from studies involving size-based isolation methods for CTCs, as they do not depend on specific antibodies. This pilot study aimed to detect CTCs from canine OMM using Isolation by Size of Epithelial Tumor Cells (ISET), a microfiltration methodology, followed by immunocytochemistry (ICC) with Melan-A, PNL2, and S100 antibodies. Ten canine patients diagnosed by histopathology and confirmed as OMM by immunohistochemistry were enrolled, their prognostic data was assessed, and blood samples were collected for CTC analysis. Results have shown the detection of intact cells in 9/10 patients. ICC has shown 3/9 Melan-A-positive, 3/9 PNL2-positive, and 8/9 S100-positive patients, confirming the importance of opting for a multimarker assay. A significant number of negative-stained CTCs were found, suggesting their high heterogeneity in circulation. Microemboli stained with either PNL2 or S100 were found in a patient with a high isolated cell count and advanced clinical stage. Preliminary statistical analysis shows a significant difference in CTC count between patients with and without lymph node metastasis (p < .05), which may correlate with tumour metastatic potential. However, we recommend further studies with more extensive sampling to confirm this result. This pilot study is the first report of intact CTC detection in canine OMM and the first application of ISET in veterinary medicine, opening new possibilities for liquid biopsy studies in canine OMM and other tumours.

Establishment of Canine Oral Mucosal Melanoma Cell Lines and Their Xenogeneic Animal Models.

Canine oral melanoma is the most prevalent malignant tumor in dogs and has a poor prognosis due to its high aggressiveness and high metastasis and recurrence rates. More research is needed into its treatment and to understand its pathogenic factors. In this study, we isolated a canine oral mucosal melanoma (COMM) cell line designated as COMM6605, which has now been stably passaged for more than 100 generations, with a successful monoclonal assay and a cell multiplication time of 22.2 h. G-banded karyotype analysis of the COMM6605 cell line revealed an abnormal chromosome count ranging from 45 to 74, with the identification of a double-armed chromosome as the characteristic marker chromosome of this cell line. The oral intralingual and dorsal subcutaneous implantation models of BALB/c-nu mice were successfully established; Melan-A (MLANA), S100 beta protein (S100ß), PNL2, tyrosinase-related protein 1 (TRP1), and tyrosinase-related protein 2 (TRP2) were stably expressed positively in the canine oral tumor sections, tumor cell lines, and tumor sections of tumor-bearing mice. Sublines COMM6605-Luc-EGFP and COMM6605-Cherry were established through lentiviral transfection, with COMM6605-Luc-EGFP co-expressing firefly luciferase (Luc) and enhanced green fluorescent protein (EGFP) and COMM6605-Cherry expressing the Cherry fluorescent protein gene. The COMM6605-Luc-EGFP fluorescent cell subline was injected via the tail vein and caused lung and lymph node metastasis, as detected by mouse live imaging, which can be used as an animal model to simulate the latter steps of hematogenous spread during tumor metastasis. The canine oral melanoma cell line COMM6605 and two sublines isolated and characterized in this study can offer a valuable model for studying mucosal melanoma.

Immunohistochemical and transcriptomic characterization of T and myeloid cell infiltrates in canine malignant melanoma.

Immune checkpoint inhibitor therapy can provide significant clinical benefit in patients with certain cancer types including melanoma; however, objective responses are only observed for a subset of patients. Mucosal melanoma is a rare melanoma subtype associated with a poor prognosis and, compared with cutaneous melanoma, is significantly less responsive to immune checkpoint inhibitors. Spontaneous canine tumours have emerged as valuable models to inform human cancer studies. In contrast to human melanoma, most canine melanomas are mucosal-an incidence that may be leveraged to better understand the subtype in humans. However, a more comprehensive understanding of the immune landscape of the canine disease is required. Here, we quantify tumour infiltrative T and myeloid cells in canine mucosal (n = 13) and cutaneous (n = 5) melanomas using immunohistochemical analysis of CD3 and MAC387 expression, respectively. Gene expression analysis using the Canine IO NanoString panel was also performed to identify genes and pathways associated with immune cell infiltration. T and myeloid cell densities were variable with geometric means of 158.7 cells/mm2 and 166.7 cells/mm2, respectively. Elevated T cell infiltration was associated with increased expression of cytolytic genes as well as genes encoding the coinhibitory checkpoint molecules PD-1, CTLA-4, TIM-3 and TIGIT; whereas increased myeloid cell infiltration was associated with elevated expression of protumourigenic cytokines. These data provide a basic characterization of the tumour microenvironment of canine malignant melanoma and suggest that, like human melanoma, inherent variability in anti-tumour T cell responses exists and that a subset of canine melanomas may respond better to immunomodulation.

Identification of hypoxia-induced metabolism-associated genes in canine tumours.

Canine tumours including urothelial carcinoma, lung adenocarcinoma, mammary gland tumour, squamous cell carcinoma, and melanoma have been identified as causes of death, but effective therapies are limited due to insufficient knowledge of the molecular mechanisms involved. Within the tumour microenvironment, hypoxia activates hypoxia-inducible factor 1α (HIF1α) in tumour cells. High HIF1α expression correlates with enhanced glycolysis and poorer outcomes in human cancers. However, the molecular mechanisms underlying hypoxic tumour cells remain elusive in dogs. In our study, we investigated upregulated genes in a canine malignant melanoma cell line during hypoxia using RNA-sequencing analysis. Glycolysis and HIF1 signalling pathways were upregulated in hypoxic melanoma cells. HIF1α knockout melanoma cells revealed that the glycolysis marker MCT4 is regulated by HIF1α activation. Hypoxia induces high lactate secretion due to enhanced glycolysis in canine melanoma cells. Furthermore, we examined monocarboxylate transporter 4 (MCT4) expression in malignant melanoma and eight other types of canine tumour tissues using immunohistochemistry (IHC). Membrane-localized MCT4 protein was mostly detected in urothelial carcinoma and lung adenocarcinoma rather than malignant melanoma. We conclude that canine MCT4 protein plays a role in lactic acid efflux from glycolytic cells and may serve as a marker for hypoxia and glycolysis in canine tumours. These findings could inform future therapeutic strategies targeting MCT4.

[Successful surgical excision of a melanoma and a rare peripheral nerve sheath tumor in 2 cattle]. / Erfolgreiche chirurgische Exzision eines Melanoms und eines seltenen peripheren Nervenscheidentumors bei 2 Rindern.

A heifer and a dairy cow were presented to our practice with cutaneous masses on the left side of their necks. Each mass had a diameter of approximately 20 cm. Both tumors had increased in size in recent weeks and were now prone to injuries from the stable equipment. Both animal owners agreed to surgical removal, which was performed under sedation and local anesthesia on a bovine treatment crush. The subsequent histopathological examinations of the extirpates revealed a melanocytoma in the young heifer and a cutaneous peripheral nerve sheath tumor (PNST) in the dairy cow. Both cases were benign tumors. The postoperative course was without complications and no recurrences were observed even more than a year later. No comparable tumors were found in related animals or in the offspring.

Extensive intraocular melanoma with secondary glaucoma in a 15-month-old Thoroughbred filly.

A 15-month-old, grey, Thoroughbred filly presented for investigation of a 6-week history of corneal oedema and blepharospasm on the right eye (OD). The filly was otherwise healthy. Following ophthalmic examination, glaucoma on the OD was diagnosed. A space occupying mass within the anterior chamber was documented on transpalpebral ultrasonographic examination. This mass obliterated most of the anterior intraocular structures on the peripheral nasal side (corneal endothelium and drainage angle), leading to secondary glaucoma. After systemic and topical treatment addressing secondary glaucoma, the corneal oedema reduced. The mass was visualised as an irregularly rounded brown structure associated with the iris on the peripheral nasal side of the anterior chamber. Given the filly's signalment, location and appearance of the mass, a tentative diagnosis of intraocular melanoma was made and enucleation was performed. Histopathological evaluation of the globe revealed solid sheets of heavily pigmented melanocytic cells, disrupting the normal ciliary body architecture and extending into the iris and subretinal. The cells were pleomorphic, polyhedral to round with occasional spindle-shaped cells, and contained moderate to large amounts of granular black-brown pigment (melanin). The iridal component expanded into the anterior chamber, with cells directly opposed to Descemet's membrane, with loss of the endothelium and expanding and occluding the filtration angle in this area. The lesion infiltrated locally into the edge of the sclera, but did not extend through the sclera, though occasional perivascular clusters of melanophages were observed within the scleral stroma adjacent to the optic nerve. Diagnosis of a uveal melanocytic neoplasm was confirmed, with characteristics similar to only one reported case . This is a unique case of a rapidly growing, invasive, uveal melanoma in a young horse. Intraocular melanoma should be considered as a differential diagnoses for glaucoma in grey horses, regardless of the age and absence of melanocytic skin lesions.

Potent drug delivery enhancement of betulinic acid and NVX-207 into equine skin in vitro - a comparison between a novel oxygen flow-assisted transdermal application device and microemulsion gels.

BACKGROUND: Gray horses are predisposed to equine malignant melanoma (EMM) with advancing age. Depending on the tumor's location and size, they can cause severe problems (e.g., defaecation, urination, feeding). A feasible therapy for EMM has not yet been established and surgical excision can be difficult depending on the location of the melanoma. Thus, an effective and safe therapy is needed. Naturally occurring betulinic acid (BA), a pentacyclic triterpene and its synthetic derivate, NVX-207 (3-acetyl-betulinic acid-2-amino-3-hydroxy-2-hydroxymethyl-propanoate) are known for their cytotoxic properties against melanomas and other tumors and have already shown good safety and tolerability in vivo. In this study, BA and NVX-207 were tested for their permeation potential into equine skin in vitro in Franz-type diffusion cell (FDC) experiments after incubation of 5 min, 30 min and 24 h, aiming to use these formulations for prospective in vivo studies as a treatment for early melanoma stages. Potent permeation was defined as reaching or exceeding the half maximal inhibitory concentrations (IC50) of BA or NVX-207 for equine melanoma cells in equine skin samples. The active ingredients were either dissolved in a microemulsion (ME) or in a microemulsion gel (MEG). All of the formulations were transdermally applied but the oil-in-water microemulsion was administered with a novel oxygen flow-assisted (OFA) applicator (DERMADROP TDA). RESULTS: All tested formulations exceeded the IC50 values for equine melanoma cells for BA and NVX-207 in equine skin samples, independently of the incubation time NVX-207 applied with the OFA applicator showed a significant time-dependent accumulation and depot-effect in the skin after 30 min and 24 h (P < 0.05). CONCLUSIONS: All tested substances showed promising results. Additionally, OFA administration showed a significant accumulation of NVX-207 after 30 min and 24 h of incubation. Further in vivo trials with OFA application are recommended.

Review of the comparative pathological and immunohistochemical features of human and canine cutaneous melanocytic neoplasms.

Melanocytic neoplasms originate from melanocytes and melanoma, the malignant form, is a common canine neoplasm and the most aggressive human skin cancer. Despite many similarities between these neoplasms in both species, only a limited number of studies have approached these entities in a comparative manner. Therefore, this review compares benign and malignant melanocytic neoplasms in dogs and humans, exclusively those arising in the haired skin, with regard to their clinicopathological, immunohistochemical and molecular aspects. Shared features include spontaneous occurrence, macroscopic features and microscopic findings when comparing human skin melanoma in the advanced/invasive stage and canine cutaneous melanoma, immunohistochemical markers and several histopathological prognostic factors. Differences include the apparent absence of active mutations in the BRAF gene in canine cutaneous melanoma and less aggressive clinical behaviour in dogs than in humans. Further studies are required to elucidate the aetiology and genetic development pathways of canine cutaneous melanocytic neoplasms. Evaluation of the applicability of histopathological prognostic parameters commonly used in humans for dogs are also needed. The similarities between the species and the recent findings regarding genetic mutations in canine cutaneous melanomas suggest the potential utility of dogs as a natural model for human melanomas that are not related to ultraviolet radiation.

Salivary metabolomic identification of biomarker candidates for oral melanoma and oral squamous cell carcinoma in dogs.

BACKGROUND: Oral melanoma (OM) and oral squamous cell carcinoma (OSCC) are frequently diagnosed in dogs, presenting a challenge in distinguishing them from benign oral tumors (BN). Salivary metabolomic biomarkers offer a practical solution because of saliva's direct contact with tumors and the noninvasive nature of collection. OBJECTIVE: Assess the diversity and abundance of the salivary metabolome in dogs with BN, OM, and OSCC using amine/phenol submetabolome analysis and high-performance chemical isotope labeling liquid chromatography-mass spectrometry (CIL LC-MS). ANIMALS: Study included 11 BN, 24 OM, 10 OSCC, and 20 healthy control dogs. METHODS: Case-control cross-sectional study was conducted to assess salivary submetabolic profiles in dogs with BN, OM, and OSCC and healthy dogs. Samples were labeled with 12C-dansyl chloride and analyzed using CIL LC-MS targeted to amine- and phenol-containing metabolites for amine/phenol submetabolome analysis. RESULTS: Distinct clusters and significant differences in metabolite concentrations were observed among the oral cancer, BN, and control groups. A total of 154 and 66 metabolites showed significantly altered concentrations, particularly in OM and OSCC, respectively, when compared with BN (Padj < .05). Potential metabolic biomarkers were identified for each cancer, including decreased concentrations of seryl-arginine and sarcosine in OSCC. Moreover, high-confidence putative metabolites were identified, including an increase in tryptophyl-threonine and a decrease in 1,2-dihydroxynapthalene-6-sulfonic acid and hydroxyprolyl-hydroxyproline for OM. CONCLUSIONS AND CLINICAL IMPORTANCE: We identified high coverage of the amine/phenol submetabolome, including seryl-arginine, and sarcosine, in OSCC. Our findings emphasize the potential of these biomarkers for distinguishing between oral OSCC and BN in dogs.

SOX-10 and TRP-1 expression in feline ocular and nonocular melanomas.

In felines, ocular and nonocular melanomas are uncommon tumors that represent a diagnostic challenge for pathologists, especially when amelanotic. To date, the immunohistochemical diagnostic panel in cats is based on specific melanocytic markers (Melan-A and PNL2) and a nonspecific but sensitive marker (S100). In human medicine, SOX-10 is reported to be a sensitive antibody for the detection of melanoma micrometastasis in the lymph node. TRP-1, an enzyme involved in melanogenesis, has recently been used in humans and dogs as a specific melanocyte marker. The aim of this study was to evaluate the cross-reactivity and the expression of SOX-10 and TRP-1 antibodies in feline normal tissue and melanocytic tumors. Thirty-one cases of ocular, cutaneous, and oral melanomas were retrospectively evaluated and confirmed by histopathological examination and by immunolabeling with Melan-A and/or PNL2. SOX-10 nuclear expression in normal tissues was localized in epidermal, subepidermal, hair bulb, and iridal stromal melanocytes and dermal nerves. In melanomas, nuclear expression of SOX-10 was detected in ocular (11/12; 92%), oral (6/7; 86%), and cutaneous sites (12/12; 100%). TRP-1 cytoplasmic immunolabeling in normal tissue was observed in epidermal and bulbar melanocytes and in the lining pigmented epithelium of the iris and in its stroma. Its expression was positively correlated to the degree of pigmentation in the tumor and was observed in 75% of ocular (9/12), 43% of oral (3/7), and 33% of cutaneous melanomas (4/12). This study demonstrated the cross-reactivity of SOX-10 and TRP-1 antibodies in feline non-neoplastic melanocytes and their expression in ocular and nonocular melanomas.

Malignant melanoma and lymph node metastases appearing as hyperattenuating masses on computed tomography in a dog.

A 16-year-old male castrated Dachshund cross dog was referred for a dental and a mass on the right side of the face. CT revealed several heterogenous precontrast hyperattenuating masses within the subcutaneous tissue over the masseter muscle, demonstrating marked contrast uptake. The ipsilateral mandibular lymph nodes were mildly enlarged and markedly hyperattenuating on precontrast images. A histopathological final diagnosis of malignant melanoma with regional lymph node metastasis was made, and the hyperattenuating appearance was postulated to be due to its melanin content. This is the first published report of melanoma appearing as hyperattenuating masses on CT in small animals.