Prognostic value of peripheral blood and bone marrow infiltration assessed by flow cytometry in dogs with de novo nodal peripheral T-cell lymphoma receiving alkylating-rich chemotherapy.

Peripheral T-cell lymphoma (PTCL) is highly aggressive in dogs and demonstrates a poor response to traditional chemotherapy. The aim of this retrospective study was to assess the prognostic significance of peripheral blood (PB) and bone marrow (BM) infiltration evaluated by flow cytometry (FC) in dogs with treatment-naïve and histologically confirmed PTCL. To be included, dogs had to undergo complete staging, including FC on lymph nodes, PB and BM samples. Additionally, dogs had to receive an alkylating-rich protocol and have a complete follow-up. Treatment response was evaluated based on RECIST criteria at each chemotherapy session, and the end-staging was conducted at the completion of treatment. Endpoints were time to progression (TTP) and lymphoma-specific survival (LSS). The relationship between TTP/LSS and the percentage of PB and BM infiltration, categorized as > 1%, > 3%, > 5%, > 10%, > 15% and > 20% was investigated. Fifty dogs were included: based on imaging and FC, 78.0% had stage 5 disease, 14.0% had stage 4, 6.0% had stage 3 and 2.0% had stage 1. By multivariable analysis, the CD4-negative phenotype was the only factor associated with a shorter TTP (P = 0.049), while BM infiltration was significantly associated with LSS (P = 0.037). Dogs with BM infiltration > 5% had shorter median LSS (114 days; 95%CI: 0-240) compared to dogs with BM infiltration ≤ 5% (178 days; 95%CI: 145-211). Lack of complete response (P = 0.039) and administration of corticosteroids before chemotherapy (P = 0.026) also significantly worsened LSS. BM flow cytometric evaluation could be considered an essential part of staging work-up for dogs with PTCL and has prognostic relevance.

A retrospective study on bone metastasis in dogs with advanced-stage solid cancer.

OBJECTIVES: To review clinical characteristics, treatment, outcome and prognostic factors in dogs with solid cancer-bearing bone metastases. MATERIALS AND METHODS: Records were reviewed from dogs with histologically-proven solid cancer and bone metastases. Clinicopathologic variables, bone metastases characteristics and skeletal-related events were recorded. Endpoints were time to bone metastases and survival. RESULTS: Fifty dogs were included, 20 of them with synchronous and 30 of them with metachronous bone metastases. In the latter group, median time to diagnosis of bone metastases was 210 days (range, 30 to 1835). Most common primary cancer locations included mammary gland (n=6), spleen (n=5) and tonsil (n=5). Most common histotypes were carcinoma (n=32) and hemangiosarcoma (n=10). Nineteen dogs had multiple bones involvement, with humeri and vertebrae more commonly affected. Twenty-four dogs received antitumoural therapy, five symptomatic treatment and 21 were not treated. Overall median survival after bone metastases diagnosis was 30 days (range, 11 to 49); 83% of dogs died because of skeletal-related events. Lack of antitumoural therapy was significantly associated with shorter survival (hazard ratio: 2.7; 95% confidence interval: 1.3 to 5.6) and with increased risk of skeletal-related death (hazard ratio: 3.3; 95% confidence interval: 1.4 to 7.4). Dogs with endocrine/neuroendocrine tumours (odds ratio: 8.8; 95% confidence interval: 1.2 to 63.9), without appendicular metastases (odds ratio: 5.1; 95% confidence interval: 1.0 to 25.8), without extra-skeletal metastases (odds ratio: 5.2; 95% confidence interval: 1.1 to 24.5) and receiving antitumoural therapy (odds ratio: 14.8; 95% confidence interval: 1.7 to 131.4) had an increased chance of surviving more than 100 days. CLINICAL SIGNIFICANCE: Bone metastases in dogs with solid cancers are associated with poor prognosis and a high risk of skeletal-related events. Treatment appears to have an impact on survival.

Lymphadenectomy improves outcome in dogs with resected Kiupel high-grade cutaneous mast cell tumours and overtly metastatic regional lymph nodes.

INTRODUCTION: Historically, the prognosis for dogs with stage II Kiupel high-grade cutaneous mast cell tumours has been considered poor. OBJECTIVES: The aim of this study was to explore the impact of lymphadenectomy on outcome in dogs with Kiupel high-grade cutaneous mast cell tumours and overt regional lymph node metastasis. MATERIAL AND METHODS: Data from dogs with completely staged Kiupel high-grade cutaneous mast cell tumours with overt and/or certain regional lymph node metastasis undergoing excision of the primary tumours and adjuvant medical treatment were extracted. Dogs with a cytological diagnosis of regional lymph node metastasis that did not undergo lymphadenectomy were compared with dogs that underwent lymphadenectomy and had a histological diagnosis of overt lymph node metastasis. RESULTS: Forty-nine dogs were included, 18 did not undergo lymphadenectomy while 31 underwent lymphadenectomy. Median time to progression was significantly shorter in dogs that did not undergo lymphadenectomy (150 days, 95% confidence interval: 129 to 170) compared to the other dogs (229 days, 95% confidence interval: 191 to 266). Median survival time was also shorter in dogs that did not undergo lymphadenectomy (250 days, 95% confidence interval: 191 to 308) compared to dogs that underwent lymphadenectomy (371 days, 95% confidence interval: 311 to 430). On multivariable analysis, lack of lymphadenectomy was associated with higher risk of overall tumour progression (hazard ratio: 2.05, 95% confidence interval: 1.02 to 4.13), nodal progression (hazard ratio: 3.4, 95% confidence interval: 1.65 to 7.02) and tumour-related death (hazard ratio 3.63, 95% confidence interval: 1.72 to 7.66), whereas tumour size was associated with higher risk of local recurrence (hazard ratio: 3.61, 95% confidence interval: 1.06 to 13). CLINICAL SIGNIFICANCE: Regional lymphadenectomy may improve outcome in dogs with biologically aggressive cutaneous mast cell tumours.

Cytological differentiation between benign and malignant perianal gland proliferative lesions in dogs: a preliminary study.

OBJECTIVES: To evaluate the diagnostic utility of individual cytological criteria and their best combination to differentiate benign from malignant perianal gland proliferative lesions in dogs. MATERIALS AND METHODS: Retrospective study of cytological samples of canine perianal gland proliferative lesions that had subsequent histopathological confirmation. RESULTS: Seventy-seven perianal gland nodules from 56 dogs were included. Histologically, lesions were diagnosed as hyperplasia (n=2), adenoma (n=53), epithelioma (n=6) and carcinoma (n=16). Of the 28 cytological criteria assessed, 13 showed promise for distinguishing benign from malignant lesions. A diagnostic algorithm with an 87% accuracy (sensitivity, 90.9%; specificity, 85.4%) was developed from these data. CLINICAL SIGNIFICANCE: Cytological evaluation can provide useful information for presurgical differentiation between benign and malignant hepatoid gland proliferative lesions. The proposed algorithm must be validated and tested for reproducibility in further, preferably larger, series of cases.

Comparison between May-Grünwald-Giemsa and rapid cytological stains in fine-needle aspirates of canine mast cell tumour: Diagnostic and prognostic implications.

Mast cell tumours (MCTs) are often diagnosed by cytology based on the identification of purple intracytoplasmic granules with methanolic Romanowsky stains, including May-Grünwald-Giemsa (MGG). In clinical practice, aqueous rapid stains (RS) are commonly used, but mast cell granules may not stain properly. Aim of this prospective study was to investigate the frequency of MCT hypogranularity with RS and its potential implications in tumour identification, cytological grading assessment and recognition of nodal metastatic disease. Cytological preparations of canine primary MCTs and metastatic lymph nodes with subsequent histopathological confirmation were included. For each case, good-quality smears were stained with both MGG and RS and comparatively assessed. Eleven of 60 (18.3%) primary MCTs were hypogranular with RS; 9 of them were histologically high-grade tumours and in 3 cases (5%) a definitive MCT diagnosis could not be made. Accuracy in cytological grading assessment (85%) did not differ between RS and MGG. Thirteen of 28 (46.4%) metastatic lymph nodes were hypogranular with RS and 3 independent observers failed to identify nodal MCT metastases in 7% to 18% of RS-stained smears. This study confirms that, in limited cases, RS can be ineffective in staining MCT granules, particularly in high-grade tumours, thus making diagnosis more dependent on experience and quality of preparations. In dubious cases, methanolic stains should be applied. The use of RS is discouraged for the search of nodal metastases, as the identification of isolated mast cells can be more challenging.

The impact of toceranib, piroxicam and thalidomide with or without hypofractionated radiation therapy on clinical outcome in dogs with inflammatory mammary carcinoma.

In dogs, inflammatory mammary carcinoma is a clinicopathological entity characterized by rapid progression and aggressive behavior from onset of disease. Reported median survival time is short, with no effective treatment options. The aims of this prospective, noncontrolled clinical trial were to investigate outcome variables and safety profile of toceranib, thalidomide and piroxicam with or without hypofractionated radiation therapy in dogs with measurable histologically confirmed inflammatory mammary carcinoma that underwent a complete staging. Eighteen dogs were enrolled: 14 received medical treatment, and 4 were treated with hypofractionated radiation therapy and medical therapy. Overall, median time to progression was 34 days and median survival time was 109 days. In dogs treated with medical therapy, overall response rate was 21%, and clinical benefit rate (CBR) was 64%; median time to progression was 28 days and median survival time was 59 days. In dogs receiving medical therapy and undergoing radiation therapy, overall response rate and clinical benefit rate were 100%, with significantly longer time to progression (156 days) and survival time (180 days). Overall, treatment was well tolerated, with mild gastrointestinal and dermatological adverse events. Although the optimal treatment to this disease remains uncertain, the current approach consisting of systemic anti-angiogenic drugs with or without hypofractionated radiation therapy, provided clinical benefit in a significant proportion of dogs and should, therefore, be further explored.

Survival analysis of dogs with advanced primary lung carcinoma treated by metronomic cyclophosphamide, piroxicam and thalidomide.

Unresectable or metastatic (advanced) primary pulmonary carcinoma (PPC) represents a therapeutic challenge where surgery may be contraindicated and the therapeutic role of maximum-tolerated dose (MTD) chemotherapy remains uncertain. This study was undertaken to explore the impact of metronomic chemotherapy (MC) in dogs with advanced PPC. Previously untreated dogs with advanced (T3 or N1 or M1) PPC, with complete staging work-up and follow-up data, receiving MC (comprising low-dose cyclophosphamide, piroxicam and thalidomide), surgery, MTD chemotherapy or no oncologic treatment were eligible for inclusion. For all patients, time to progression (TTP) and survival time (ST) were evaluated. Quality-of-life (QoL) was only evaluated in patients receiving MC. To assess QoL, owners of dogs receiving MC were asked to complete a questionnaire before and during treatment. Ninety-one dogs were included: 25 received MC, 36 were treated with surgery, 11 with MTD chemotherapy and 19 received no treatment. QoL was improved in dogs receiving MC. Median TTP was significantly longer in patients receiving MC (172 days) than patients undergoing surgery (87 days), receiving MTD chemotherapy (22 days), or no oncologic treatment (20 days). Median ST was similarly longer in patients receiving MC (139 days) than those undergoing surgery (92 days), MTD chemotherapy (61 days) and no oncologic treatment (60 days). In dogs with advanced PPC, MC achieved a measurable clinical benefit without significant risk or toxicity. This makes MC a potential alternative to other recognized management approaches.

Features and prognostic impact of distant metastases in 45 dogs with de novo stage IV cutaneous mast cell tumours: A prospective study.

BACKGROUND: Distant metastases in dogs with cutaneous mast cell tumors (cMCT) are rare and incurable. The aims of this prospective study were to clarify the clinico-pathological features of stage IV cMCTs and to identify possible prognostic factors for progression-free interval (PFI) and survival time (ST). MATERIAL AND METHODS: Dogs were eligible for recruitment if they had a previously untreated, histologically confirmed cMCT and if they underwent complete staging demonstrating stage IV disease. Dogs were uniformly followed-up, whereas treatment was not standardized and included no therapy, surgery, radiation therapy, chemotherapy, tyrosine-kinase inhibitors or a combination of these. RESULTS: 45 dogs with stage IV cMCT were enrolled. All dogs had distant metastatic disease, and 41 (91.1%) dogs had also metastasis in the regional lymph node. Histopathological grade and mutational status greatly varied among dogs. Median ST was 110 days. Notably, PFI and ST were independent of well-known prognostic factors, including anatomic site, histological grade, and mutational status. Conversely, tumor diameter >3 cm, more than 2 metastatic sites, bone marrow infiltration, and lack of tumor control at the primary site were confirmed to be negative prognostic factors by multivariate analysis. CONCLUSION: Currently, there is no satisfactory treatment for stage IV cMCT. Asymptomatic dogs with tumor diameter <3 cm and a low tumor burden, without bone marrow infiltration may be candidates for multimodal treatment. Stage IV dogs without lymph node metastasis may enjoy a surprisingly prolonged survival. The achievement of local tumor control seems to predict a better outcome in dogs with stage IV cMCT.

Feline large granular lymphocyte lymphoma: An Italian Society of Veterinary Oncology (SIONCOV) retrospective study.

Feline large granular lymphocyte (LGL) lymphoma is an uncommon subtype of lymphoma characterized by a grave prognosis and scarce response to chemotherapy. There are limited reports on clinico-pathological and prognostic factors. One-hundred and 9 cats with newly diagnosed LGL lymphoma that underwent initial staging (including hematology, serum biochemistry, thoracic radiographs and abdominal ultrasound), and followed-up were retrospectively evaluated. LGL lymphoma was localized within the gastrointestinal tract with or without extra-intestinal involvement in 91.7% of the cases, and at extra-gastrointestinal sites in 8.3%. Symptoms were frequent. Anemia (31.2%) and neutrophilia (26.6%) were commonly observed, and 14 (12.8%) cats had neoplastic circulating cells. Frequent biochemistry abnormalities included elevated ALT (39.4%) and hypoalbuminemia (28.4%). Twenty (54.1%) of 37 cats had elevated serum LDH. Treatment varied among cats, and included surgery (11%), chemotherapy (23%), corticosteroids (38.5%) and no treatment (27.5%). Median time to progression (MTTP) was 5 days, and median survival time (MST) 21 days. MST was significantly shorter in the case of substage b, circulating neoplastic cells, lack of chemotherapy administration, and lack of treatment response. A small subset of cats (7.3%) survived more than 6 months, suggesting that a more favorable clinical course can be found among LGL lymphoma patients.

Comparative Assessment of the Accuracy of Cytological and Histologic Biopsies in the Diagnosis of Canine Bone Lesions.

BACKGROUND: Osteosarcoma (OSA) should be differentiated from other less frequent primary bone neoplasms, metastatic disease, and tumor-like lesions, as treatment and prognosis can vary accordingly. Hence, a preoperative histologic diagnosis is generally preferred. This requires collection of multiple biopsies under general anesthesia, with possible complications, including pathological fractures. Fine-needle aspiration cytology would allow an earlier diagnosis with a significant reduction of discomfort and morbidity. HYPOTHESIS/OBJECTIVES: The aim of this study was to compare the accuracy of cytological and histologic biopsies in the diagnosis of canine osteodestructive lesions. ANIMALS: Sixty-eight dogs with bone lesions. METHODS: Retrospective study. Accuracy was assessed by comparing the former diagnosis with the final histologic diagnosis on surgical or post-mortem samples or, in the case of non-neoplastic lesions, with follow-up information. RESULTS: The study included 50 primary malignant bone tumors (40 OSAs, 5 chondrosarcomas, 2 fibrosarcomas, and 3 poorly differentiated sarcomas), 6 carcinoma metastases, and 12 non-neoplastic lesions. Accuracy was 83% for cytology (sensitivity, 83.3%; specificity, 80%) and 82.1% for histology (sensitivity, 72.2%; specificity, 100%). Tumor type was correctly identified cytologically and histologically in 50 and 55.5% of cases, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: The accuracy of cytology was similar to histology, even in the determination of tumor type. In no case was a benign lesion diagnosed as malignant on cytology. This is the most important error to prevent, as treatment for malignant bone tumors includes aggressive surgery. Being a reliable diagnostic method, cytology should be further considered to aid decisions in the preoperative setting of canine bone lesions.

A retrospective analysis of chemotherapy switch suggests improved outcome in surgically removed, biologically aggressive canine haemangiosarcoma.

Haemangiosarcoma (HSA) has an aggressive biological behaviour and carries a poor prognosis, with less than 10% of treated dogs surviving longer than 1 year. In this retrospective study a varied metronomic chemotherapy (MC) regimen preceded by adjuvant doxorubicin-based maximum-tolerated dose chemotherapy (MTDC) was compared with MTDC, in terms of efficacy [time to metastasis, (TTM) and survival time (ST)] and safety in dogs with biologically aggressive HSA. Dogs were eligible if they had no metastasis after MTDC and received either no further chemotherapy or MC maintenance. Twelve dogs received MTDC, and 10 received MC thereafter. Median TTM and ST were significantly longer for dogs receiving MTDC-MC (not reached versus 150 days, P = 0.028; and not reached versus 168 days, P = 0.030, respectively). Treatment was well tolerated. MTDC followed by MC is safe and suggests improved TTM and ST in dogs with surgically removed, biologically aggressive HSA that are treated in the microscopic setting.

Kit receptor tyrosine kinase dysregulations in feline splenic mast cell tumours.

This study investigated Kit receptor dysregulations (cytoplasmic immunohistochemical expression and/or c-KIT mutations) in cats affected with splenic mast cell tumours. Twenty-two cats were included. Median survival time was 780 days (range: 1-1219). An exclusive splenic involvement was significantly (P = 0.042) associated with longer survival (807 versus 120 days). Eighteen tumours (85.7%) showed Kit cytoplasmic expression (Kit pattern 2, 3). Mutation analysis was successful in 20 cases. Fourteen missense mutations were detected in 13 out of 20 tumours (65%). Eleven (78.6%) were located in exon 8, and three (21.6%) in exon 9. No mutations were detected in exons 11 and 17. Seven mutations corresponded to the same internal tandem duplication in exon 8 (c.1245_1256dup). Although the association between Kit cytoplasmic expression and mutations was significant, immunohistochemistry cannot be considered a surrogate marker for mutation analysis. No correlation was observed between c-Kit mutations and tumour differentiation, mitotic activity or survival.

Conformity and controversies in the diagnosis, staging and follow-up evaluation of canine nodal lymphoma: a systematic review of the last 15 years of published literature.

Diagnostic methods used in the initial and post-treatment evaluation of canine lymphoma are heterogeneous and can vary within countries and institutions. Accurate reporting of clinical stage and response assessment is crucial in determining the treatment efficacy and predicting prognosis. This study comprises a systematic review of all available canine multicentric lymphoma studies published over 15 years. Data concerning diagnosis, clinical stage evaluation and response assessment procedures were extracted and compared. Sixty-three studies met the eligibility criteria. Fifty-five (87.3%) studies were non-randomized prospective or retrospective studies. The survey results also expose variations in diagnostic criteria and treatment response assessment in canine multicentric lymphoma. Variations in staging procedures performed and recorded led to an unquantifiable heterogeneity among patients in and between studies, making it difficult to compare treatment efficacies. Awareness of this inconsistency of procedure and reporting may help in the design of future clinical trials.

Differentiating feline inflammatory bowel disease from alimentary lymphoma in duodenal endoscopic biopsies.

OBJECTIVES: This study aimed to evaluate the agreement between microscopic and molecular testing for differentiating feline intestinal bowel disease and small cell alimentary lymphoma in duodenal endoscopic biopsies. METHODS: Four different diagnostic methods (cytology, histology, immunohistochemistry and clonality) were sequentially applied to 77 cases of feline chronic enteropathies. The agreement between the different diagnostic methods was calculated and survival data were obtained to assess the most reliable method for predicting outcome. RESULTS: Seventy-seven cases were included in the study. On multivariate survival analysis, only the clonality-based diagnosis of lymphoma was significantly associated with poor survival, with a risk of enteropathy-related death 2·8 times higher. By comparing the other tests with clonality, specificity was high (87 to 97%), whereas sensitivity was 36·8% for cytology, 39·5% for histology, 63·2% for immunohistochemistry, resulting in an overall accuracy of 62·3, 68·8 and 80·5%, respectively. CLINICAL SIGNIFICANCE: Clonality analysis can consistently increase the possibility of correctly and early diagnosing small cell lymphoma on endoscopic biopsies. Histological suspicion of alimentary lymphoma, even if not confirmed by clonality, should never be ignored, as it may represent a debutant form of lymphoma or it may later progress to lymphoma.

Enhanced therapeutic effect of APAVAC immunotherapy in combination with dose-intense chemotherapy in dogs with advanced indolent B-cell lymphoma.

The aim of this non-randomized controlled trial was to compare time to progression (TTP), lymphoma-specific survival (LSS), and safety of an autologous vaccine (consisting of hydroxyapatite ceramic powder and Heat Shock Proteins purified from the dogs' tumors, HSPPCs-HA) plus chemotherapy versus chemotherapy alone in dogs with newly diagnosed, clinically advanced, histologically confirmed, multicentric indolent B-cell lymphoma. The vaccine was prepared from dogs' resected lymph nodes and administered as an intradermal injection. Forty-five client-owned dogs were enrolled: 20 dogs were treated with dose-intense chemotherapy, and 25 received concurrent immunotherapy. Both treatment arms were well tolerated, with no exacerbated toxicity in dogs also receiving the vaccine. TTP was significantly longer for dogs treated with chemo-immunotherapy versus those receiving chemotherapy only (median, 209 versus 85 days, respectively, P=0.015). LSS was not significantly different between groups: dogs treated with chemo-immunotherapy had a median survival of 349 days, and those treated with chemotherapy only had a median survival of 200 days (P=0.173). Among vaccinated dogs, those mounting an immune response had a significantly longer TTP and LSS than those with no detectable response (P=0.012 and P=0.003, respectively). Collectively these results demonstrate that vaccination with HSPPCs-HA may produce clinical benefits with no increased toxicity, thereby providing a strategy for enhancing chemotherapy in dogs with advanced indolent lymphoma.

Histopathological findings and proliferative activity of canine sebaceous gland tumours with a predominant reserve cell population.

Sebaceous gland tumours represent the third most common skin tumours in dogs, but diagnostic criteria for tumours with basal differentiation (i.e. sebaceous epithelioma) are poorly defined and there is lack of correlation with biological behaviour. The aim of this study was to identify the main histological criteria associated with malignancy in 30 canine sebaceous gland tumours with a predominant reserve cell population. For each case, tumour proliferative activity was assessed by determining mitotic index and the Ki67/MIB-1 index. Additional histological features included endophytic or exophytic growth, proportion of reserve/intermediate/mature cells, connection to the epidermis, nuclear characteristics, peripheral invasion, neoplastic emboli and necrosis. Mitotic and Ki67 indexes were variable, but correlated (R = 0.66; P < 0.001), and both were significantly higher in infiltrative tumours (P = 0.018 and P < 0.001, respectively). No significant difference in histological features was observed between tumours comprised of more or less than 90% reserve cells, nor among tumours showing proliferative activity in sebocytes. This study suggests that high proliferative activity and peripheral invasion should be considered the most significant parameters for the differentiation between benign and malignant sebaceous gland tumours. Furthermore, the incidence of circumanal gland and testicular tumours in these dogs was significantly higher compared with an age-matched control population, suggesting a potential androgen-related pathway for the tumourigenesis of canine sebaceous gland neoplasms.

Histologic grading of canine mast cell tumor: is 2 better than 3?

Mast cell tumor (MCT) is a common canine cutaneous neoplasm with variable biological behavior. A 2-tier histologic grading system was recently proposed by Kiupel et al to reduce interobserver variation and eliminate prognostic uncertainty of the Patnaik system. This study compared the ability of these 2 grading systems to predict survival in a cohort of dogs with MCTs. However, surgical margins were unknown, and the risk of developing new/metastatic MCTs was not studied. Histologic grade was assessed according to both systems for 137 surgically resected cutaneous MCTs. The relationship between grade and survival was evaluated. According to the Patnaik system, 18 MCTs (13.1%) were classified as grade I, 83 (60.6%) as grade II, and 36 (26.3%) as grade III. Grade III was associated with a poorer prognosis (P < .001), but no significant difference between grades I and II was detected. Grading according to the Patnaik system was based on consensus grading among 3 pathologists, and interobserver variability was not considered. All grade I MCTs were low grade in the Kiupel system, and all grade III were high grade. Among grade II, 71 (85.6%) were low grade, and 12 (14.4%) were high grade, with a 1-year survival probability of 94% and 46%, respectively (P < .001). The 2-tier system had a high prognostic value and was able to correctly predict the negative outcomes of some grade II MCTs. Data also confirm that histologic grading cannot predict biological behavior of each MCT and should be supplemented with molecular methods for more accurate prognostication.

EGFR overexpression in canine primary lung cancer: pathogenetic implications and impact on survival.

This study reports the main clinicopathological features of primary lung cancer (PLC) in 37 dogs, with special regard to the pathogenetic and prognostic role of epidermal growth factor receptor (EGFR) overexpression. For each case the following characteristics were evaluated: tumour-node-metastasis (TNM) stage, tumour histotype, histological grade, mitotic activity and immunohistochemical expression of EGFR. In samples with available normal lung tissue, the amount of background anthracosis was also measured by image analysis. In 27 tumours (73%) a variable number of cells (20-100%) stained positively for EGFR. The proportion of EGFR-positive tumours was significantly higher in cases with background anthracosis, and the amount of anthracosis was correlated with the percentage of positive tumour cells. Additionally, a trend towards shortened survival for the high EGFR group was observed. These findings suggest an involvement of EGFR signalling pathway in canine PLC, a negative prognostic significance of protein overexpression and its potential implication in air pollution carcinogenesis.

Prognostic significance of Kit receptor tyrosine kinase dysregulations in feline cutaneous mast cell tumors.

Feline cutaneous mast cell tumors (FeCMCTs) are characterized by variable biological behavior. Development of multiple nodules and potential visceral involvement, along with inconsistency of conventional prognostic aids, justify uncertainty in differentiating benign from malignant forms. c-Kit proto-oncogene activating mutations have been reported in feline mast cell tumors (MCTs), but their prognostic relevance was not investigated. This study was performed on FeCMCTs with variable clinical outcome to assess whether Kit cytoplasmic immunohistochemical labeling can be regarded as indicative of c-Kit mutations and to evaluate the relationship between Kit dysregulation and survival. Twenty-four cats diagnosed with a primary cutaneous MCT were enrolled. Kit immunohistochemical pattern and c-Kit (exons 8, 9, 11) mutational status were assessed in 34 tumor samples. Risk factors affecting survival were a number of mitoses greater than 5 per 10 HPFs (P = .017) and cytoplasmic Kit labeling (P = .045). Increased mitotic activity was associated with Kit cytoplasmic expression (P = .01). c-Kit encoding mutations were present in 19 (56%) tumors (exon 8, 19%; exon 9, 71%; exon 11, 10%), however, they were not significantly related to protein expression and they had no influence on prognosis. Additionally, in 6 of 9 (67%) cats, multiple nodules from the same cat had different mutational statuses. Mutations in the fifth immunoglobulin-like domain of Kit occur frequently in FeCMCT, but they are variably associated with aberrant protein expression and do not appear to be strictly correlated with biological behavior. These findings need to be confirmed in larger series, and exploration of further genomic regions of c-Kit is warranted.

Prognostic value of histologic and immunohistochemical features in feline cutaneous mast cell tumors.

Feline cutaneous mast cell tumors (MCTs) have been histologically classified as mastocytic (well differentiated or pleomorphic) and atypical/poorly granulated. Their biologic behavior ranges from benign to malignant, but prognostic factors are not well defined. Histologic classification, number of tumors, mitotic index, cytoplasmic granularity, and infiltration by eosinophils or lymphocytes were evaluated retrospectively in 25 feline cutaneous MCTs. Immunohistochemistry was applied to assess KIT (CD117) pattern and immunoreactivity score, telomerase expression (human telomerase reverse transcriptase), and proliferation index (MIB-1/Ki67 index). Case outcome was obtained via telephone interviews. The tumors comprised 15 mastocytic well-differentiated, 7 mastocytic pleomorphic, and 3 atypical/poorly granulated MCTs. Immunohistochemically, CD117 was expressed in 13 of 25 tumors (52%), and telomerase reverse transcriptase was expressed in 15 of 22 (68%), with no correlation to histologic classification. Mitotic index, KIT immunoreactivity score, and Ki67 index were significantly higher in mastocytic pleomorphic MCTs than in the other 2 categories. Five cats (20%) died of tumor-related causes. Multiplicity of lesions, pleomorphic phenotype, KIT immunoreactivity score, and mitotic and Ki67-indices correlated with an unfavorable outcome. Mitotic index was the strongest predictive variable. These results suggest that histologic classification, CD117/KIT immunohistochemistry, and proliferation indices may help to identify potentially aggressive cases of feline cutaneous MCT. Aberrant KIT protein localization and telomerase immunoreactivity warrant further exploration as potential prognostic markers.