Search Results (44)

Background/Objective: Basal cell carcinoma (BCC) is the most common cutaneous malignancy, arising from epidermal basal cells or the outer root sheath of the pilosebaceous unit. Despite its generally indolent clinical behavior, BCC exhibits substantial histopathological heterogeneity, which may reflect underlying biological differences among its subtypes. This study aimed to evaluate the expression of Wnt/β-catenin pathway components and tumor-associated markers—including COX-2, Ki-67, tryptase, CD1a, and WNT3A—across different histopathological subtypes of BCC. Methods: This retrospective cross-sectional study included 100 formalin-fixed paraffin-embedded (FFPE) BCC specimens retrieved between January 2006 and September 2015. After the exclusion of three cases due to inadequate tissue quality, the tumors were classified into nodular (n = 60), infiltrative (n = 16), superficial (n = 9), and other subtypes (n = 12). The immunohistochemical expressions of COX-2, Ki-67, CD1a, intratumoral and peritumoral tryptase, β-catenin, and WNT3A were assessed and compared among the BCC subtypes. Results: No significant differences were observed among the BCC subtypes regarding age or sex distribution. The expression levels of COX-2, Ki-67, CD1a, and mast cell-associated markers (intratumoral and peritumoral tryptase) did not differ significantly among the groups (all p > 0.05). Conversely, β-catenin expression was significantly higher in the infiltrative subtype compared with the other histological variants (p = 0.001). WNT3A immunoexpression was uniformly negative across all evaluated cases. Conclusions: Most of the evaluated immunohistochemical markers did not differentiate among the BCC subtypes. However, the significantly increased β-catenin expression observed in the infiltrative subtype suggests a potential association with tumor growth patterns rather than serving as a specific discriminative marker, thereby highlighting the biological heterogeneity of BCC. Although WNT3A expression was uniformly negative in all cases, this finding should be interpreted cautiously and does not allow for definitive conclusions regarding its role in Wnt pathway activation. Overall, these results support the need for further investigation into the Wnt/β-catenin pathway heterogeneity in BCC. Full article

Mast cell tumors are the most common skin neoplasm in dogs and may be influenced by reproductive status. A gonadectomy modifies gonadotropin levels and may affect the expression of hormonal receptors and proliferative factors; however, the evidence for this remains limited. The objective of this study was to evaluate the expression of VEGF, IGF-1, PCNA, Ki-67, c-KIT, LHR, FSHR, and ERα in intact and neutralized female dogs with and without MCTs. Gene expression in the skin samples was quantified by a real-time PCR, and four groups were included: intact controls (n = 10), neutralized controls (n = 10), intact MCT (n = 9), and neutralized MCT (n = 10). Tumor presence was associated with increased expression of LH and FSH receptors and c-KIT, while angiogenic and proliferative factors (PCNA, Ki-67, IGF-1, VEGF, and ERα) showed lower expression. In dogs with MCTs, a gonadectomy was associated with higher c-KIT and VEGF expression but lower LHR mRNA levels. PCNA expression was lower in the neutralized MCT dogs compared to the neutralized controls, whereas no differences were observed in the intact dogs. Additionally, ERα expression was higher in the neutralized control dogs than in the intact controls, with no differences detected in the MCT dogs. These findings suggest that reproductive status is associated with differential regulation of molecular pathways involved in canine MCT biology. Full article

The use of digitized slides for histopathological diagnosis has become common in veterinary pathology, and the validation of diagnostic techniques that are extrapolated from the evaluation of glass slides is needed. The goal of this study is to evaluate the efficiency of counting mitotic figures in physical glass slides and digitized slides of cutaneous tumors of dogs and cats. The mitotic count was performed by three pathologists on glass and digitized slides of ninety skin tumors, including 30 squamous cell carcinomas in dogs and cats, 30 mast cell tumors and 30 soft tissue tumors in dogs. An additional assessment of cellular proliferation was performed with immunohistochemistry for Ki67. Spearman’s correlation for the mean count of mitotic figures between the three observers on physical and digitized slides demonstrated a strong positive correlation for squamous cell carcinomas and mesenchymal tumors and a moderate correlation for mast cell tumors. Inter-observer agreement was moderate between the two methods. In conclusion, the results found suggest that digitized slides can be used reliably for mitotic figure counting in cutaneous neoplasms in small animals, without compromising their classification or prediction of prognosis. Full article

Cancer is a major health concern, with its incidence rate continuing to increase. There is growing interest in the microbiota and its role in carcinogenesis, as it significantly influences physiological and pathological processes. Various aspects of the microbiome have been shown to have both anti-tumor and pro-tumor effects. Advances in techniques such as high-throughput DNA sequencing have greatly improved our understanding of microbial populations in the human and canine gut. We aimed to (1) characterize the intestinal microbiota of healthy dogs and dogs with cutaneous mast cell tumors (MCTs), (2) assess changes in the intestinal microbiota of dogs undergoing electrochemotherapy (ECT) combined with gene electrotransfer (GET) of the IL-12 plasmid (IL-12), and (3) explore possible associations with the expression of immune markers Programmed cell death protein 1 (PD-1), Programmed death-ligand 1 (PD-L1), and Granzyme B (GZMB) in MCT tissue. Stool samples were collected from healthy dogs (n = 24) and dogs with MCTs (n = 24) before and after ECT and IL-12 GET. DNA was extracted from the samples, and shallow shotgun sequencing was performed. Immunohistochemistry was performed on the tumors to assess the expression of PD-1, PD-L1, and GZMB. The dysbiosis index, alpha diversity, and beta diversity did not differ between groups. Regarding microbial composition, Bifidobacterium animalis, Corynebacterium variabile, Lactobacillus johnsonii, Pediococcus pentosaceus, Streptococcus anginosus, Streptococcus equinus, Streptococcus intermedius, Clostridium thermobutyricum, Megasphaera elsdenii, and Anaerobiospirillum sp. were found in lower relative abundance in feces of dogs with MCTs, while Bacteroides togonis, Lactobacillus amylolyticus, Prevotella sp. CAG:279, and Megamonas hypermegale were more abundant compared to healthy dogs. Our study provides further insight into the composition of the gut microbiota in dogs with MCTs, where ECT and IL-12 GET did not lead to major shifts. We were unable to establish any association between the expression of immune markers and the microbiota. Full article

Cutaneous melanoma remains one of the most aggressive tumors, yet the role innate immunity plays in its progression remains poorly understood. Effector elements with high regulatory potential, capable of both promoting and inhibiting tumor growth—mast cells (MCs), are of particular interest. This includes quantitatively characterizing the interactions between tryptase-positive mast cells (MCs) with atypical Melanin—A⁺ cells and describing their spatial phenotype, in relation to the stage of cutaneous melanoma. A retrospective analysis was carried out on samples retrieved from 128 patients with cutaneous melanoma (AJCC 8th edition: IA–IIID). Histological analysis, histochemistry (toluidine blue, Giemsa), and diplex /multiplex IHC for tryptase and Melan-A were performed; as well as Fluorescence imaging, 3D reconstructions and quantitative mapping in QuPath v 0.6.0. Proximity was assessed by the nucleus-to-nucleus distance: <10 μm (contact), 10–20 μm (paracrine zone), >20 μm (out of interaction). The relative amount of MCs in the intratumoral zone was lower than in the intact dermis, with a simultaneous increase in their absolute density per mm² in the melanoma microenvironment, maximum in the peritumoral area and most pronounced at stage II. Three types of interactions were identified: (i) juxtaposition without secretion, (ii) degranulation of MCs directed to tumor cells, (iii) melanosecretion of Melanin—A⁺ cells directed towards MCs, followed by phagocytosis of melanocores. An inverse intratumoral connection between the number of MCs and the number of Melanin—A⁺ cells was noted; MCs with elongated forms, extensive contacts and polarized tryptase secretion, including granule localization near/at the nuclei of adjacent cells, were frequently observed. The obtained data indicate stage-region-dependent bidirectional cross-talk between melanin and MCs, forming tissue spatial signals, potentially useful as biomarkers and targets for personalized therapy. Full article

Background: Myxoid glomus tumors (mGTs) are an uncommon histologic pattern of glomus tumors, characterized by prominent myxoid stromal changes that may mimic a wide range of soft tissue neoplasms. Recent reports of unexpected CD34 expression in some cases have further complicated their differential diagnosis. Objectives: This study aimed to characterize the histopathological, immunohistochemical, and clinical features of cutaneous mGTs, with particular emphasis on CD34 expression. Methods: We analyzed 8 histologically confirmed cases of cutaneous mGTs underwent to a comprehensive evaluation of morphological features and immunophenotypic profile, with available clinical data. The immunohistochemical panel included smooth muscle actin (SMA), CD34, and S100. Mast cell density was assessed by tryptase in 3 cases. As controls, 8 glomus tumors without myxoid features were also examined for CD34 expression. Results: The cohort consisted of 8 patients (2 males, 6 females; age range 23–71 years). All tumors were located on the distal phalanges of the digits and showed extensive myxoid stromal changes. Immunohistochemistry demonstrated SMA positivity and CD34 expression in all mGTs. In contrast, none of the control GTs without myxoid stroma expressed CD34. Mast cells were consistently identified in the tested cases, predominantly within the myxoid matrix, suggesting a possible role in stromal remodeling. Conclusions: mGTs represent a rare but distinct histological pattern within the glomus tumor spectrum; frequent CD34 expression and mast cell infiltration appear to be characteristic features, although their biological significance remains uncertain. Recognition of these findings is essential to avoid misdiagnosis with other CD34-positive perivascular neoplasms or myxoid soft tissue sarcomas. Full article

Background: Mast cells, key effectors of the innate immune system, are known to participate in various stages of tumor progression, including inflammation, angiogenesis, and extracellular matrix remodeling. Their role in melanoma, particularly in relation to Breslow thickness, pT stage, and AJCC staging, remains unclear. This study aims to quantitatively and phenotypically assess mast cell infiltration in cutaneous melanoma at different stages of progression, focusing on Tryptase- and Chymase-positive subtypes. Methods: This retrospective multicenter study included 124 patients with cutaneous melanoma (AJCC 8th edition, stages IA–IIIC). Histological sections were stained with hematoxylin and eosin, and mast cells were visualized using toluidine blue and immunohistochemistry with anti-Tryptase and anti-Chymase antibodies. Mast cells were counted manually in intratumoral and peritumoral regions by two independent observers. Quantitative data were analyzed using non-parametric tests and presented as median [Q1–Q3]. Results: Histological examination of 124 melanoma samples confirmed typical features of cutaneous melanoma, with nodular melanoma being the most common subtype (68 cases, 54.8%) and the lower extremities identified as the predominant tumor location (47 cases, 37.9%). Toluidine blue staining verified the presence of mast cells in both intratumoral and peritumoral compartments, with the highest density observed in early-stage melanomas. Immunohistochemical analysis identified both Tryptase+ and Chymase+ mast cells. The intratumoral number of Tryptase+ cells declined from 17 [14–19] per HPF at AJCC stage IA to 6 [5–7] per HPF at stage IIIC, while Chymase+ mast cells decreased from 14 [11–16] per HPF to 2 [1–3] per HPF over the same stages. Peritumoral counts also showed a downward trend, although less pronounced. Overall, the most significant reduction was observed in Chymase+ mast cells, suggesting their potential role as markers of melanoma progression. Conclusions: This study highlights the dynamic changes in mast cell populations in cutaneous melanoma, with a pronounced decrease in Chymase⁺ mast cells as the tumor progresses. Further research is needed to explore the mechanistic role of mast cells and their phenotypic shifts in melanoma progression. Full article

Studies worldwide report cutaneous neoplasms in dogs; however, data in the arid regions of Mexico remain scarce. Here we report the main malignant cutaneous neoplasms diagnosed by fine needle aspiration cytology (FNAC), and describe the associations with age, sex and breed in Mexicali. Neoplastic lesions accounted for 25.52% (698/2735) of the cases, of which 56.59% (395/698) were malignant. The highest prevalence was observed in dogs aged 9–12 years (n = 193), intact males (n = 162), and mixed-breed dogs (n = 247). Round cell neoplasms (n = 309), including lymphoma, transmissible venereal tumors (TVT), and mast cell tumors (MCT), were the most common cell lineage. Using dogs aged 0–4 years as the reference group, dogs aged 9–12 years had 0.241 times the odds of developing malignant neoplasms (95% CI: 0.141–0.415, p = 0.0025). Using neutered males as the reference group, intact females showed 2.499 times the odds of developing malignant neoplasms (95% CI: 1.462–4.271, p = 0.0042). Compared to mixed-breed dogs, Schnauzers (OR = 0.161) showed significantly lower odds of malignancy (95% CI: 0.082–0.317, p = 0.0004), while Pitbull Terriers had 1.748 times more chance of present malignant neoplasia (95% CI: 1.014–3.013, p < 0.0001). This study provides significant epidemiological evidence on canine cutaneous neoplasms in an arid region of Mexico, identifying key risk factors and distribution patterns that can guide preventive, diagnostic, and therapeutic strategies tailored to regional characteristics. Full article

Cutaneous neoplasia is among the most common illnesses in dogs and can pose significant risks. Accurate morphological diagnosis of these conditions is vital for effective treatment and management. In this retrospective study, a total of 3746 canine skin biopsies were submitted to a veterinary reference diagnostic laboratory and evaluated using histopathology. The variables assessed included age, sex, breed, lesion, location, and histopathological diagnosis. Non-neoplastic lesions accounted for 61% of all analyzed samples, while neoplastic tumors accounted for 39%. When looking at age, dogs ranging 3–6 years and 7–9 years had at least six times higher risk of developing malignant neoplasia compared to those aged 0–2 years. Among the malignant neoplasms, mast cell tumors, hemangiosarcoma, and squamous cell carcinoma were the most observed, representing 30%, 18%, and 12% of cases, respectively. The breeds most frequently affected by malignant neoplasms included Pit Bull Terriers, Boxers, and mixed breeds, all of which comprised the majority of mast cell tumor cases at 50.54%. These findings are novel in this field and may assist small animal veterinarians in making preliminary diagnoses, while also helping pet owners understand the importance of skin cancer and its early detection. Full article

Background/Objectives: Mast cell tumors (MCTs) are the second most common malignant neoplasms in dogs. Histopathological grading and clinical staging are the main tools for estimating biological behavior and disease extent; thus, both are essential for therapeutic decision-making and prognostication. However, the biological behavior of MCTs in dogs is variable, and it sometimes deviates from expectations. In a previous study, we identified 12 transcripts whose expression profile allowed a clear distinction between Kiupel low-grade and high-grade cutaneous MCTs (cMCTs) and was associated with prognosis. Building on these findings, this study evaluated the predictive potential of these transcripts’ expression profiles in classifying cMCTs into low-grade and high-grade. Methods: A logistic regression classifier based on the expression profiles of the identified transcripts and able to classify cMCTs as low- or high-grade was developed and subsequently tested on a novel dataset of 50 cMCTs whose expression profiles have been determined in this study through qPCR. Results: The developed logistic regression classifier reaches an accuracy of 67% and an area under the receiver operating characteristic curve (AUC) of 0.76. Interestingly, the molecular classification clearly identifies stage-IV disease (90% true positive rate). Conclusions: qPCR analysis of these biomarkers combined with the machine learning-based classifier might serve as a tool to support cMCT clinical management at diagnosis. Full article

Mast cell tumors (MCTs) are common skin neoplasms in dogs. Prognostic indicators include histologic grade, clinical stage, high Ki-67 index, elevated argyrophilic nucleolus organizer regions (AgNOR) index, c-kit mutations, and recurrence after surgery. Blood serum redox status has been shown to correlate with prognostic factors in canine lymphoma and mammary tumors. This study aimed to assess the correlation between established prognostic factors and serum redox status and lipid metabolism analytes in dogs with MCTs. Dogs with cutaneous (n = 33) or subcutaneous (n = 6) MCTs, without comorbidities, were studied. Staging was evaluated based on cytology of regional lymph nodes and ultrasound-guided liver and spleen aspiration cytology. Histologic grading and immunohistochemical staining for Ki-67 and KIT patterns were performed on excised tumor specimens. Dogs were categorized by Patnaik grading (1–3), Kiupel grading (low/high), metastatic status, Ki-67 positive nuclei per cm² (>23 or ≤23), and KIT pattern (I, II–III). Paraoxonase-1, Butyrylcholinesterase, Cupric Reducing Antioxidant Capacity (CUPRAC), Diacron Reactive Oxygen Metabolites (d-ROMs), and oxy-adsorbent levels were measured before any therapeutic intervention. ANOVA and independent t-tests were used to detect differences in the mean values among groups. Paraoxonase-1 activity was significantly lower in Patnaik grade 3 (p = 0.003) and Kiupel high-grade (p = 0.022) MCTs. No significant differences were found in CUPRAC, d-ROMs, or oxy-adsorbent levels across different prognostic groups. This study found a significant correlation between histologic grading and Paraoxonase-1 activity, suggesting a potential role of Paraoxonase-1 as a prognostic biomarker in canine MCTs. Full article

Canine mast cell tumors (MCTs) are common skin neoplasms with varying biological behaviors. The KIT proto-oncogene plays a key role in the development of these tumors, and internal tandem duplications on exon 11 are usually associated with more aggressive behavior, increased local recurrence, and decreased survival time. However, apart from exons 8–11 and 17, there is limited understanding of the overall KIT mutational landscape in canine MCTs. This work aims to analyze the entire KIT coding sequence (21 exons) in a cohort of 62 MCTs, which included 38 cutaneous and 24 subcutaneous tumors, and potentially identify new variants. In addition to confirming previously reported activating KIT mutations in exons 8, 9, and 11, we identified new variants in exons 2, 3, 5, 16, and the 3′ untranslated region (UTR). Notably, these last variants include an amino acid change (Asp/His) in exon 16. Additionally, we confirmed a differential prevalence of KIT variants in cutaneous and subcutaneous MCTs. These findings enhance our understanding of the KIT proto-oncogene coding sequence and provide valuable information for future confirmatory studies. Full article

A cutaneous mast cell tumor (cMCT) is among the most common tumors in dogs. Endocannabinoids (eCBs) belong to the endocannabinoid system (ECS), which involves also cannabinoid receptors and an enzymatic system of biosynthesis and degradation. In this study, plasma levels of N-arachidonoylethanolamine (AEA), 2-arachidonoylglycerol (2-AG), N-palmitoylethanolamine (PEA), and N-oleoylethanolamine (OEA) were evaluated in 17 dogs with MCTs of varying histological grades and clinical stages, as well as in a control group of 11 dogs. Dogs affected by cMCT had higher plasma levels of 2-AG (p = 0.0001) and lower levels of AEA (p = 0.0012) and PEA (p = 0.0075) compared to the control group, while no differences were observed at the OEA level between healthy and cMCT dogs (p = 0.9264). The ability of eCBs to help discriminate between healthy and cMCT dogs was interrogated through the area under the ROC curve (AUC). An accuracy of 0.98 (95% confidence interval [CI], 0.94–1.02) was found for 2-AG, of 0.85 (95% CI, 0.71–0.99) for AEA, and of 0.81% for PEA (95% CI, 0.64–0.69). Values > 52.75 pmol/mL for 2-AG showed 94% sensitivity and 90% specificity in distinguishing cMCT. This is the first study to demonstrate alterations in plasmatic levels of eCBs in dogs affected by MCTs, suggesting the significance of these biomarkers in the tumorigenic process and their potential use as biomarkers in the future. Full article

Objective: Canine cutaneous mast cell tumors (cMCTs) have variable rates of recurrence and metastasis. We evaluated how various prognostic factors affect survival, recurrence, and metastasis in dogs with cMCT who underwent surgery and vinblastine chemotherapy. Animals: 90 dogs with cMCT treated with surgery and vinblastine at a veterinary referral institution were included. Methods: Medical records were retrospectively reviewed. Prognostic factors were evaluated. Results: Most dogs (94%) had grade 2 or 3 cMCTs. Neoadjuvant vinblastine was used in 18 dogs, and none progressed locally before surgery. The use of neoadjuvant vinblastine was associated with a higher chance of local recurrence (p = 0.03) but not survival. Shorter survival times were found for tumors that were high-grade (p < 0.001), grade 3 (p < 0.001), or a MC of >5 (p < 0.001). Dogs with grade 2 tumors that were low-grade lived longer than those with high-grade tumors (p < 0.001). Histologic tumor-free margins and the ability to achieve local tumor control were not associated with outcome. Clinical Relevance: Both grading systems and MC were prognostic for survival in this population of dogs, supporting the need for the standard reporting of histopathologic findings. Neoadjuvant chemotherapy can be effective in downsizing cMCTs but does not influence survival. These findings are consistent with previous publications, showing the benefits of a more modern population of patients, surgical treatments, and histopathologic assessments. Full article

The innate immune system, composed of neutrophils, basophils, eosinophils, myeloid-derived suppressor cells (MDSCs), macrophages, dendritic cells (DCs), mast cells (MCs), and innate lymphoid cells (ILCs), is the first line of defense. Growing evidence demonstrates the crucial role of innate immunity in tumor initiation and progression. Several studies support the idea that innate immunity, through the release of pro- and/or anti-inflammatory cytokines and tumor growth factors, plays a significant role in the pathogenesis, progression, and prognosis of cutaneous malignant melanoma (MM). Cutaneous melanoma is the most common skin cancer, with an incidence that rapidly increased in recent decades. Melanoma is a highly immunogenic tumor, due to its high mutational burden. The metastatic form retains a high mortality. The advent of immunotherapy revolutionized the therapeutic approach to this tumor and significantly ameliorated the patients’ clinical outcome. In this review, we will recapitulate the multiple roles of innate immune cells in melanoma and the related implications for immunotherapy. Full article