Subcutaneous Mast Cell Tumors Research Articles

The 2-tier grading system identifies canine cutaneous and/or subcutaneous mast cell tumors with aggressive biological behavior regardless of growth model.

Histologic grading of canine cutaneous mast cell tumors (cMCTs) has prognostic and therapeutic implications, yet validation for subcutaneous MCTs (scMCTs) is lacking. For scMCTs with or without dermal invasion, determining their biological behavior remains poorly standardized and sometimes sparks controversy. This prospective study aimed to assess the prognostic utility of the 2-tier histologic grading system in MCTs with different growth models (GMs) and explore the prognostic impact of the GM itself. We assessed 6 histologic GM categories: solely cMCT (C-SC0), cMCT with superficial (C-SC1) or deep subcutaneous (C-SC2) involvement, solely scMCT (SC-C0), and scMCT with deep (SC-C1) or superficial (SC-C2) infiltration of the dermis. Ninety-one MCTs from 76 dogs undergoing excision and regional/sentinel lymphadenectomy were examined. GM classification identified 11 (12%) C-SC0 tumors, 12 (13%) C-SC1, 15 (16%) C-SC2, 21 (23%) SC-C0, 15 (16%) SC-C1, and 17 (19%) SC-C2. Mitotic count, 2-tier grade, nodal involvement, surgical margins, and outcome were stratified according to GM. scMCTs lacking dermal invasion, historically associated with a benign clinical course, had a poor prognosis in 10% of cases. cMCTs exhibiting deep subcutaneous involvement included the largest percentage of high-grade tumors (33%), had the highest occurrence of overt nodal metastases (33%), and had the lowest 1-year survival rate (86%). Histologic grade was confirmed as a relevant prognostic factor, surpassing nodal involvement and histologic margin status. The 2-tier histologic grading enabled the identification of all MCTs with aggressive biological behavior, regardless of their cutaneous or subcutaneous location.

Weishaar's classification system for nodal metastasis in sentinel lymph nodes: Clinical outcome in 94 dogs with mast cell tumor.

The therapeutic role and prognostic relevance of lymphadenectomy in mast cell tumor (MCT) has historically been evaluated on regional rather than sentinel lymph nodes. To update information about the association of histological nodal (HN) classes with clinical outcome in dogs with MCT after tumor excision and extirpation of normal-sized sentinel nodes (SLN) guided by radiopharmaceutical. Ninety-four dogs with histologically-confirmed treatment-naïve MCT (71 cutaneous, 22 subcutaneous and 1 conjunctival MCT) were included if without: distant metastases, lymphadenomegaly, concurrent mixed cutaneous, and subcutaneous MCT. This was a monoistitutional cohort study. Tumors characteristics were retrieved and SLNs were classified according to Weishaar's system. Incidence of MCT-related events (local, nodal, distant relapse), de novo MCT or other tumors and death (MCT-related and non-MCT-related), were recorded. Incidence curves were compared among the HN classes. Twenty-seven dogs had HN0, 19 HN1, 37 HN2, and 11 HN3 SLN. Thirteen (2 HN0, 4 HN2, and 7 HN3) received adjuvant chemotherapies. Kiupel high grade, increasing number of SLN and lymphocentrums were associated with higher HN classes. Five dogs died for MCT-related causes: 1 low-grade (HN0) and 1 subcutaneous (HN3) had a local relapse, 2 high-grade had distant relapse (HN3-HN0) and 1 dog developed disease progression from a de novo subcutaneous MCT. No nodal relapse was registered. Fourteen dogs developed de novo MCTs. Low grade/low-risk MCT with nonpalpable and normal sized SLN have a favorable outcome independently from the HN. Result should be considered strictly related to the successful SLN detection guided pre- and intraoperative by radiopharmaceutical markers.

CT features of cutaneous and subcutaneous canine mast cell tumors and utility of conventional and indirect lymphography to detect clinically unknown mast cell tumors and to map the sentinel lymph nodes.

Computed tomography is frequently used to stage canine mast cell tumors (MCTs). The aims of this prospective, observational study were to describe the CT features of MCTs, to evaluate the performance of CT in detecting additional or incidental MCTs, to distinguish between cutaneous (cMCT) or subcutaneous (scMCT) MCTs, and to identify one or multiple sentinel lymph nodes (SLNs) by indirect CT lymphography (ICTL). Seventy-two dogs affected by 111 MCTs were included. The recorded parameters were: shape, size, attenuation (Hounsfield units [HU]), location (cutaneous or subcutaneous), and presence of fat stranding. The SLNs were compared with the regional lymph nodes and supplementary MCTs were registered. Mast cell tumors mostly appeared with well-defined margins (89%), round/oval shape (71%), homogeneous enhancement (90%) with a mean postcontrast density of 62.0±23.4 HU and associated with fat stranding (43%). Cutaneous mast cell tumors were more frequently round (P=.003), whereas scMCTs were oval (P=.011) with a larger mean maximal diameter (2.91±1.57cm vs 1.46±1.28cm, P=.002) and more feeding vessels (77% vs 39% P=.044). Compared with histopathology, CT accuracy in differentiating cMCTs and sMCTs was 57%, with an interobserver agreement of 88% (three reviewers). Indirect CT lymphography showed the SLN in 82 of 85 (97%) cases, 32% of them not corresponding to the regional node. CT showed additional or incidental MCTs in 23 of 72 (32%) dogs. In conclusion, the common CT appearance of canine cMCTs and scMCTs is reported with some statistical differences between the two categories. CT is useful in identifying clinically undetected MCTs and SLNs, although it shows low accuracy in distinguishing between cMCT and scMCT.

Caracterização histopatológica e análise de proliferação celular em 162 casos de mastocitoma subcutâneo em cães no Brasil

ABSTRACT: There are limited publications about canine subcutaneous mast cell tumors (MCT). International studies have shown that subcutaneous MCT has longer survival times than cutaneous MCT, with lower recurrence and metastasis rates. In addition, subcutaneous MCT has a specific histopathological classification (circumscribed, combined, or infiltrative pattern). Our study evaluated 162 cases of subcutaneous MCT diagnosed from 2014 to 2017 in Brazil. The mean age of the animals was 8.6 years, with a predominance of females and higher incidence in dogs with mixed breed (n=40), followed by Boxer (n=20), Labrador Retriever (n=14), Golden Retriever (n=11) and Pug (n=10). Regarding histopathological characterization, the most common infiltrative pattern represented 54.3% of cases, followed by circumscribed (34.8%) and combined (11%) patterns. The mean mitotic index (MI) was 1.04, with 93.9% of cases presenting MI≤4 and 53.1% MI=0. The data found in this Brazilian study regarding subcutaneous MCT does not differ from those described in American studies, suggesting similar genetic and epidemiological factors. The evaluated proliferation indices suggest that subcutaneous MCT presents slow progression and should be evaluated as a distinct form of cutaneous MCT.

Correlation between computed tomography and histological evaluation of nodal metastasis in dogs with mast cell tumours.

Early diagnosis of nodal metastasis has been shown to impact prognosis for dogs with mast cell tumours (MCT). The objective of this retrospective study was to determine the correlation between computed tomographic characteristics of lymph nodes and histologic nodal metastasis using the HN classification system, in dogs with cutaneous or subcutaneous MCT and regional lymph node(s) removal. Dogs that had removal of MCT and regional lymphadenectomy within 31 days of the initial staging computed tomography (CT) were enrolled. Subjective lymph node characteristics used included margination, loss of fat at hilus, shape of margin, perinodal fat pattern, increase in number of nodes, and pre- and post-contrast heterogeneity. Enhancement, heterogeneity, and short-long axis ratio were calculated. Seventy-one lymph nodes from 37 dogs were included. Generalised linear mixed model of assessment of lymph node was performed twice, with binary outcome [non-metastatic (HN0/1) versus metastatic (HN2/3)] and 4-point scales (HN0-HN3). After blind assessment of 7 characteristics described above, a final subjective interpretation of each lymph node as non-metastatic or metastatic was assigned. A significant correlation was found between final interpretation and prediction of metastasis. Higher HN classification was also significantly correlated with the increased number of nodes and pre- and post-contrast heterogeneity. No correlation was found in short-long axis ratio, calculated heterogeneity, or degree of enhancement. Sensitivity of CT was 35.7%, specificity was 96.6%, and accuracy was 60.5% for nodal metastasis. CT alone cannot be recommended for assessment of metastasis. The use of multiple computed tomographic characteristics may increase accuracy of nodal metastasis detection.

Development of a flow cytometric panel to assess prognostic biomarkers in fine needle aspirates of canine cutaneous or subcutaneous mast cell tumors

Development of a flow cytometric panel to assess prognostic biomarkers in fine needle aspirates of canine cutaneous or subcutaneous mast cell tumors

Tibial Plateau and Stifle Joint Invasion with a Subcutaneous Mast Cell Tumor.

A 4 yr old female neutered Labrador retriever was referred with a history of left hind-limb lameness and an acute, nonpainful, subcutaneous mass on the medial aspect of the left stifle. Stifle radiographs and fine needle aspirates of the soft tissue mass performed by the referring veterinarian confirmed the presence of predominantly highly granulated mast cells, consistent with a mast cell tumor. Computed tomography demonstrated a soft tissue mass centered on the left medial stifle, with associated joint effusion and polyostotic lytic lesions on the tibial plateau and distal patella. Ultrasound-guided aspirates of the liver, spleen, and popliteal lymph nodes were obtained to rule out further metastatic spread. Cytology of the joint fluid demonstrated a low number of well-differentiated mast cells. Surgical and oncological interventions were discussed, and full hind-limb amputation was elected. Histopathological analysis of the submitted tissues after amputation diagnosed a subcutaneous mast cell tumor with neoplastic cell infiltrate extending into sections of joint capsule and synovial membrane. Infiltration to the tibia and distal patella were suspected following the presence of mast cell clusters in both osteolytic lesions. No evidence of metastasis was identified in the popliteal lymph node. Postoperative monitoring of iliac lymph node size using ultrasound did not identify evidence of metastasis 12 mo postoperatively.

What clinicopathological factors predict prognosis for canine subcutaneous mast cell tumours?

What clinicopathological factors predict prognosis for canine subcutaneous mast cell tumours?

Diagnostic imaging findings of subcutaneous mast cell tumor in a dog

A 5-year-old Labrador Retriever presented with a subcutaneous mass on the right scapular region with localized calor. On magnetic resonance imaging (MRI), a heterogeneously hypointense mass was seen on T1-weighted images (WI) and hyperintense on T2WI and fat-suppressed T2WI with marginal contrast enhancement on postcontrast T1WI and invasion into the surrounding tissue. Histopathological examination of the mass confirmed subcutaneous mast cell tumor (MCT) infiltrating to the adjacent subcutaneous fat. This is the first report to describe the MRI findings of subcutaneous MCT in veterinary medicine. This study suggests that MRI may help evaluate the extent of invasion of subcutaneous MCT.

Subcutaneous mast cell tumours: A prospective multi-institutional clinicopathological and prognostic study of 43 dogs.

Canine subcutaneous mast cell tumours (ScMCTs) reportedly have a good prognosis. However, biomarkers that can be used to predict outcome are currently limited. A multicentre prospective study was conducted to identify new prognostic markers. Dogs with a first occurrence of ScMCT were enrolled upon primary tumour removal and regional lymphadenectomy. In the absence of metastasis, dogs were monitored, while dogs with overtly metastatic lymph nodes (histological node 3, HN3) received adjuvant vinblastine. Forty-three dogs were enrolled: 15 (34.9%) had at least one HN3 lymph node and received vinblastine, and 28 (65.1%) were monitored. Three tumours harboured exon 8 and 9 c-kit mutations. Eight (18.6%) dogs experienced tumour progression, and five (11.6%) died of MCT-related causes. The 1- and 2-year survival rates were 90% and 77%, respectively. Variables significantly associated with an increased risk of progression included high cytograde, a mitotic count (MC) greater than 4/10 high-power fields (hpf) and Ki67-index greater than 23. An MC greater than 4/10 hpf was also associated with an increased risk of tumour-related death. Regional rather than sentinel lymphadenectomy was performed in these dogs. Dogs were enrolled in oncology referral centres, constituting a different population compared to previous studies. ScMCTs have a good prognosis. However, the metastatic rate at admission was higher in this study than previously reported, and a subset of tumours were associated with a fatal outcome despite multimodal treatment. Proliferative activity and cytograding may predict more aggressive behaviour in ScMCTs.

Sentinel lymph node mapping in canine mast cell tumours using a preoperative radiographic indirect lymphography: Technique description and results in 138 cases.

Several sentinel lymph node (SLN) mapping techniques, to detect nodal metastasis in canine tumours have been investigated in the last 10 years in veterinary oncology. The purpose of this prospective study was to describe a reliable, quick, and inexpensive technique for SLN mapping in canine patients affected by cutaneous and subcutaneous mast cell tumours (MCT). Eighty dogs were enrolled in this study for a total of 138 cytologically diagnosed MCTs. Sentinel lymph node mapping was performed by injecting iomeprole peritumorally followed by serial radiographs at 1, 3, 6 and 9-min post injection. A total of 168 SLNs were detected, 90% at first radiograph, 1 min after the peritumoral iomeprole injection, while in the rest of the cases SLN was identified at 3 min. Sentinel lymph nodes detected by the preoperative radiographic indirect lymphography with iomeprole (PRILI) differed from regional lymph nodes in 57% of cases. The PRILI technique detected simultaneously multiple SLNs in the 26% of cases and multiple lymph centers in the 31% of MCTs. To allow the surgical identification of the SLNs, a peritumoral injection of methylene blue was performed at the time of surgery. This study reports a widely available technique for SLN mapping using digital radiographs in combination with a water-soluble medium, representing a cost-effective alternative to other SLN mapping procedures. Based on our results, this technique can be effective for SLNs mapping in dogs with MCTs but further comparative studies are needed to assess its reliability and efficacy in different tumours.

Pre-operative neoadjuvant vinblastine-prednisolone in canine mast cell tumours: A single-centre retrospective cohort study.

Neoadjuvant chemotherapy can be used in canine mast cell tumours (MCTs) to optimise surgical margins or to enable marginal excision in challenging locations. The objective of this study was to describe the outcome of dogs with cutaneous and subcutaneous MCTs treated with neoadjuvant vinblastine-prednisolone (NA-VP). Records of treatment-naïve dogs with cutaneous/subcutaneous MCT that received NA-VP were reviewed including signalment, indication for NA-VP, staging results, clinical response, surgical data and histopathology reports. For dogs with post-operative follow-up ≥365 days, predictive factors for local recurrence (LR) were evaluated. Forty-four dogs were included. NA-VP was indicated to optimise surgical margins (group MARG) in 19 dogs (43.2%) and to enable surgery (group MORB) in 25 dogs (56.8%). Complete and partial response were documented in 40.9% of dogs and 30 dogs (68.2%) underwent surgery. The indication for NA-VP was significantly associated with undergoing surgery (p < .001) on multivariable analysis. Twelve (48%) and 18 dogs (94.7%) underwent surgery in the group MORB and MARG, respectively. Five dogs (16.7%) experienced wound dehiscence. Complete excision was achieved in 14 dogs (46.7%). In dogs undergoing surgery with ≥365 days of follow-up, LR was documented in five cases (20.8%). None of the factors analysed including mitotic count, completeness of excision and response to NA-VP were associated with LR; notably, LR occurred in 3/11 (27.2%) completely excised MCTs. In a pre-operative setting, NA-VP appears safe and could be beneficial in selected cases. Prognostic factors such as clinical response, mitotic count and completeness of excision should be interpreted with caution following NA-VP.

Retrospective analysis of outcome and prognostic factors of subcutaneous mast cell tumours in dogs undergoing surgery with or without adjuvant treatment.

Subcutaneous mast cell tumours (SC MCTs) can display a different biological behaviour in dogs when compared to their cutaneous counterpart. There is a paucity of information with regards to the outcome of dogs with SC MCTs treated with surgery and/or receiving adjuvant chemotherapy. The aim of this study was to retrospectively review the outcome of dogs with surgically excised SC MCTs undergoing adjuvant treatment or not. A secondary aim was to assess prognostic factors in the same group. Fifty-two cases were included. Recurrence rate was 15% and 63% of evaluated lymph nodes were consistent with early or overt metastasis. Median survival time (range 83-1357 days) and median time to progression (range 14-1357 days) were not reached. Factors predictive of shorter overall survival time included increasing age (HR 1.29, 95% CI 1.06-1.55, p = .0092), presence of clinical signs at presentation (HR 10.44, 95% CI 2.69-40.52, p = .0007), mitotic count >4 (HR 8.69, 95% CI 2.55-29.55, p = 0.0005), presence of multinucleation (HR 4.21, 95% CI 1.35-13.18, p = .0135), use of neoadjuvant and adjuvant chemotherapy (HR 7.16, 95% CI 1.26-40.73, p = .0266). The same factors, together with increasing tumour dimensions, were predictive for shorter progression-free survival (PFS), including increasing age (p = .0012), presence of clinical signs at presentation (p = .0045), increasing tumour dimensions (p = .0004), MC > 4 (p = .0004), presence of multinucleation (p = .0282), use of neoadjuvant and adjuvant chemotherapy (p = .0485). No variables remained significant for overall survival using multivariate analysis. There was a longer survival in cases where chemotherapy was not required (HR 0.14, 95% CI 0.03-0.68, p = .0148), and this variable remained significant for PFS on multivariate analysis (HR 0.13, 95% CI 0.02-0.76, p = .02). In conclusion, our study suggests that dogs with SC MCTs, in the absence of negative prognostic factors, may have a prolonged survival when treated with surgery alone. Further studies are needed to clarify the role of adjuvant treatment for biologically aggressive SC MCTs in dogs.

Factors affecting prognosis in canine subcutaneous mast cell tumors: 45 cases.

To evaluate the clinical outcome of subcutaneous mast cell tumors (SQMCT) and to identify clinical and histological characteristics of more aggressive disease. Retrospective study. Forty-five dogs with 48 SQMCTs. Medical records were reviewed (2011-2021) for patient information, clinical, and histopathological data including multinucleation, necrosis, invasion into local muscle, an infiltrative growth pattern, tumor grade (if listed), mitotic index, and surgical margins. The presence of local recurrence, lymph node metastasis, survival time, and other parameters evaluating patient outcome were also recorded. Local recurrence occurred in 17.8% (8/45) of dogs, 11.1% (5/45) developed metastatic recurrence, and 26.7% (12/45) developed lymph node metastasis. Dogs with lymph node metastases had a median disease-free interval (DFI) of 194 days (18-1864), while median DFI was not reached for dogs without lymph node metastasis (p=.0012). Median survival time for dogs with lymph node metastasis was 551 days (110-2050) compared to 1722 days (10-1722) without metastasis (p=.0432). Local recurrence resulted in a significantly shorter median survival time of 551 days (80-2050) compared to 1722 days (10-1722) for dogs without local recurrence (p=.0038). Dogs with infiltrative tumors had a median DFI of 268 days (3-1722) and DFI for dogs without an infiltrative pattern had not reached median at 1864 days (10-1864) (p=.011). Lymph node metastasis decreased disease-free interval and survival. Subcutaneous mast cell tumors may be a more aggressive disease than previously reported.

Salivary miR-21 is a potential biomarker for canine mast cell tumors.

MicroRNAs (miRNAs) are a class of noncoding RNA molecules playing a crucial role in tumor modulation targeting mRNA. This study aimed to validate the diagnostic potential of a panel of 3 miRNAs previously identified in canine mast cell tumors (MCTs), miR-21, miR-379, and miR-885, as markers of lymph node involvement in terms of histological absence (nonmetastatic: HN0; premetastatic: HN1) and presence (early-metastatic: HN2; overt-metastatic: HN3) of metastasis, in the saliva of mast cell tumor (MCT)-affected dogs by quantitative polymerase chain reaction (PCR). Forty-seven saliva samples were analyzed: 36 from MCT-affected dogs (12 subcutaneous [3 HN0-1 and 9 HN2-3] and 24 cutaneous [9 HN0-1 and 15 HN2-3-MCT]) and 11 from healthy dogs. MCT-group effects were investigated using analysis of variance (ANOVA). The origin of the tumor affected the expression of salivary miR-21 (P = .011) with an increase in cases with subcutaneous MCTs compared with the healthy group (P = .0005) and those with cutaneous MCTs (P = .004). Salivary miR-21 was higher in the HN2-3 class compared with the healthy group (P = .004). Salivary miR-885 was not affected by the presence of MCT, while miR-379 was not detected in saliva. The diagnostic potential of salivary miR-21 in discriminating MCT-affected dogs from the healthy group (AUC = 0.8917), cutaneous from subcutaneous (AUC = 0.8111), and subcutaneous HN0-1 (AUC = 0.7250) and HN2-3 (AUC = 0.9750) classes from healthy samples was demonstrated by receiver operating characteristic curve analysis. Overall, salivary miR-21 was identified as a promising tool, representing a novel approach to detecting MCT-associated epigenetic alterations in a minimally invasive manner.

Mutations in Exons 8 and 11 of c-kit Gene in Canine Subcutaneous Mast Cell Tumors and Their Association with Cell Proliferation.

Simple SummaryMast cell tumors (MCTs) are one of the most common skin tumors in dogs with variable clinical behavior ranging from benign lesions to those causing widespread metastasis. Prognostic factors have been intensively studied in cutaneous MCTs but are less commonly investigated in subcutaneous MCTs as the majority are benign. Activating mutations in exons 8 and 11 of c-kit, a gene that regulates proliferation and differentiation of mast cells, occur commonly in canine cutaneous MCTs and are strong predictors of prognosis. c-kit mutations have rarely been reported in subcutaneous MCTs. The goal of this study was to identify the prevalence of c-kit mutations in exons 8 and 11 in 216 canine subcutaneous MCTs and to investigate their association with other prognostic factors, including mitotic count, histologic grade, KIT pattern and proliferation markers. We detected c-kit mutations in exons 8 and 11 in 23 (10.6%) and 12 (5.56%) subcutaneous MCTs, respectively. c-kit mutations in exon 11 were associated with histologic high grade and a high mitotic count, suggesting that these parameters can predict the biological behavior of subcutaneous MCTs in a similar manner as in their cutaneous counterparts.The prognostic significance of internal tandem duplication (ITD) mutations in exons 8 and 11 of c-kit has been well-described for canine cutaneous mast cell tumors (MCTs), but c-kit mutations have rarely been reported in subcutaneous MCTs. The objective of this study was to identify the prevalence of ITD mutations in exons 8 and 11 of c-kit in canine subcutaneous MCTs and to investigate its association with histologic grade, KIT pattern, and proliferation markers. ITD mutations in exons 8 and 11 of c-kit, mitotic count, Ki67 index, AgNOR number, Ki67xAgNOR score, KIT pattern, and histologic grade (two-tier system) were retrospectively recorded for 216 dogs with subcutaneous MCTs. ITD mutations in exons 8 and 11 of c-kit were detected in 23 (10.6%) and 12 (5.56%) subcutaneous MCTs, respectively. Exon 11 mutations were significantly associated with Kiupel high grade (p < 0.001) and increased mitotic count (p < 0.001) compared to subcutaneous MCTs with no mutations in exons 8 or 11 (p = 0.002) or subcutaneous MCTs with a mutation in exon 8 (p = 0.001). There was no significant association of either c-kit mutation with KIT patterns or proliferation activity. This study identified a higher prevalence of ITD mutations in exons 8 and 11 of c-kit in subcutaneous MCTs than previously reported. Like their cutaneous counterpart, subcutaneous MCTs with exon 11 mutations were more likely to be histologically high grade and have a higher mitotic count, whereas such associations were not observed in subcutaneous MCTs with exon 8 mutations.

[Successful local treatment of a digital canine mast cell tumour with Tigilanol Tiglate].

Surgical excision is currently the recommended treatment for resectable, nonmetastatic mast cell tumours. Recently, Tigilanol tiglate has become available as a novel intratumoral treatment modality for a subset of cutaneous and subcutaneous mast cell tumours. In the presented case, we document the successful treatment of a 0.445 cm3 subcutaneous digital mast cell tumour in an American Staffordshire Terrier. The resulting wound healed completely and without complications within 4 weeks and the dog was recurrence-free 8 months after treatment. Due to this new intratumoral treatment it was possible to preserve the digit, while a complete surgical resection of the tumour would have required digital amputation.

Canine mast cell tumours part I: Clinical and survival outcomes.

BackgroundDogs have a species‐specific susceptibility for developing mast cell tumours (MCTs). Mutations in the KIT proto‐oncogene (KIT) are known to contribute to the neoplastic biology of mast cells. In dogs, the most common KIT mutation is an internal tandem duplication (ITD) in exon 11 which has been considered a useful prognostic supplement to traditional histopathological tumour grading.ObjectiveThe aim of this retrospective study was to explore the importance of KIT exon 11 ITD mutation status and known clinical and pathological indices in predicting prognosis in a cohort of Australian dogs diagnosed with MCT.MethodsClinical parameters, survival data, and KIT mutation status were collected and assessed for 220 dogs with cutaneous or subcutaneous MCT (n = 189 and n = 31, respectively).ResultsIn at least one of the multivariable models, tumour grade (cutaneous Kiupel low or high grade) or tumour subcutaneous location, multiple concurrent MCTs, metastasis at the time of surgery, and senior age were statistically significant in predicting the outcome (MCT‐related death and/or second MCT diagnosis) at 6‐ or 12‐month post‐tumour excision. KIT exon 11 ITD mutation status was not a significant predictor in any of the final multivariable models and was strongly correlated with high histological grade (p < 0.001).ConclusionIn this sample of dogs, tumour histological grading remained the single most powerful prognostic indicator for MCT outcome. However, concurrent evaluation of multiple prognostically significant parameters provides information of potential value to inform therapeutic management for each patient.

Diagnosis, Prognosis and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors.

Mast cell tumors (MCTs) are hematopoietic neoplasms composed of mast cells. It is highly common in dogs and is extremely important in the veterinary oncology field. It represents the third most common tumor subtype, and is the most common malignant skin tumor in dogs, corresponding to 11% of skin cancer cases. The objective of this critical review was to present the report of the 2nd Consensus meeting on the Diagnosis, Prognosis, and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors, which was organized by the Brazilian Association of Veterinary Oncology (ABROVET) in August 2021. The most recent information on cutaneous and subcutaneous mast cell tumors in dogs is presented and discussed.

Canine cutaneous and subcutaneous mast cell tumours: a narrative review.

Cutaneous and subcutaneous mast cell tumours are common neoplasms in the dog. While the majority can be treated with adequate local therapy alone, a subset demonstrates a biologically aggressive behaviour associated with local recurrence or metastasis. This article reviews the diagnosis and tumour staging of canine mast cell tumours alongside treatment options and the evidence supporting their use. In addition, prognostic markers are evaluated to highlight how one can recognise mast cell tumours that may behave in a biologically aggressive manner as well as the challenges of tumours that are large, infiltrative or in locations not amenable to wide surgical excision.