KIT Staining Pattern Research Articles

Investigation of the Theragnostic Role of KIT Expression for the Treatment of Canine Mast Cell Tumors with Tyrosine Kinase Inhibitors.

Several reports have indicated that canine MCTs express a mutated form of a tyrosine kinase receptor, namely KIT, that is involved in abnormal mast cell growth and differentiation. Currently, the post-surgical prognosis for MCTs is related to three different KIT immunohistochemical expression patterns. However, to our knowledge, there are few studies specifically exploring the efficacy of treatment with tyrosine kinase inhibitors related to KIT staining pattern. The purpose of this study was to investigate the potential theragnostic role of KIT expression patterns by studying their correlation to the overall survival and progression-free survival in dogs treated with only tyrosine kinase inhibitors immediately after surgery. We selected 66 cases of canine cutaneous MCTs with complete clinical background. A statistical analysis was performed to assess the overall survival status. Our data suggest an important role of KIT in the etiopathogenesis of canine MCTs and indicate that the anomalous cytoplasmatic distribution of KIT is potentially related to a lower efficacy of tyrosine kinase inhibitors, thus providing a significant prognostic information about the treatment outcome.

Immunohistochemical and Molecular Genetic Analysis of Canine Digital Mast Cell Tumours.

Grading, immunohistochemistry and c-kit mutation status are criteria for assessing the prognosis and therapeutic options of canine cutaneous mast cell tumours (MCTs). As a subset, canine digital MCTs have rarely been explored in this context. Therefore, in this retrospective study, 68 paraffin-embedded canine digital MCTs were analysed, and histological grading was assessed according to Patnaik and Kiupel. The immunohistochemical markers KIT and Ki67 were used, as well as polymerase chain reaction (PCR) for mutational screening in c-kit exons 8, 9, 11 and 14. Patnaik grading resulted in 22.1% grade I, 67.6% grade II and 10.3% grade III tumours. Some 86.8% of the digital MCTs were Kiupel low-grade. Aberrant KIT staining patterns II and III were found in 58.8%, and a count of more than 23 Ki67-positive cells in 52.3% of the cases. Both parameters were significantly associated with an internal tandem duplication (ITD) in c-kit exon 11 (12.7%). French Bulldogs, which tend to form well-differentiated cutaneous MCTs, had a higher proportion of digital high-grade MCTs and ITD in c-kit exon 11 compared with mongrels. Due to its retrospective nature, this study did not allow for an analysis of survival data. Nevertheless, it may contribute to the targeted characterisation of digital MCTs.

In situ c-KIT mRNA quantification of canine cutaneous mast cell tumours and its relationship to prognostic factors.

Cutaneous mast cell tumours (MCTs) are the most frequent malignant skin tumours in dogs. Mutations in the c-KIT proto-oncogene are correlated with the pathogenesis and aggressiveness of MCTs. To date, studies have focused on c-KIT mutations and KIT protein localization, with a general lack of mRNA-level analyses. In this study, c-KIT mRNA expression was investigated in canine MCTs by RNA in situ hybridization (RNA-ISH). Furthermore, we evaluated associations between c-KIT mRNA expression and the histological grade, KIT immunohistochemical staining pattern and other clinicopathological parameters. c-KIT mRNA expression was observed in all MCT samples, appearing as clusters of dots in the cytoplasm of neoplastic cells. A significant correlation was detected between c-KIT mRNA expression (quantified according to the H-score and the percentage of positive cells) and the histological grade (determined using two-and three-tier grading systems; P < .05). We also found a significant positive correlation (all P < .05) between c-KIT mRNA expression and the proliferation indices (mitotic index, Ki-67, and Ag67). However, no significant associations with c-KIT expression from RNA-ISH were found with respect to different KIT staining patterns. Overall, these results demonstrate that c-KIT mRNA expression might be an additional tool for measuring the c-KIT status in canine cutaneous MCTs and could serve as a potential prognostic factor. Further studies should evaluate the prognostic significance of c-KIT mRNA expression in a large and uniform cohort of canine MCTs.

High-Grade Cutaneous Mast Cell Tumour with Widespread Intrathoracic Metastasis and Neoplastic Pericardial Effusion in a Dog

An 8-year-old neutered male French Bulldog was presented with a 2-day history of intermittent vomiting, reduced appetite and recent rapid development of multiple cutaneous masses over the head and neck regions. On presentation, the patient had a moderate volume of pericardial and bilateral pleural effusion. Echocardiography demonstrated irregular, heterogeneous thickening of the walls of the right ventricle and right atrium, consistent with infiltrative intramyocardial disease. Cytological examination of fine needle aspirates from one of the cutaneous masses confirmed a mast cell tumour. Pericardial fluid analysis revealed a haemorrhagic neoplastic effusion due to mast cell neoplasia. Histopathological and immunohistochemical examination of tissues obtained post mortem confirmed a high-grade cutaneous mast cell tumour with metastasis to the heart, pericardium, mediastinum and spleen. No metastatic disease was present in the submandibular lymph nodes or liver. Immunohistochemistry demonstrated KIT staining pattern 2. There was strong nuclear Ki67 labelling in an average of 65.0cells per grid and an average of three positive AgNORs per nucleus in neoplastic cells. Polymerase chain reaction for the activating duplication mutation in exons 8 and 11 of c-Kit were negative. To the authors' knowledge, this is the first report of a canine cutaneous mast cell tumour associated with neoplastic pericardial effusion and widespread intrathoracic metastasis.

Comparative aspects of mast cell neoplasia in animals and the role of KIT in prognosis and treatment.

Mast cell neoplasia clinical presentation and biological behaviour vary considerably across mammalian species, ranging from a solitary benign mass to an aggressive systemic malignancy. Mutations in the KIT Proto‐Oncogene Receptor Tyrosine Kinase (KIT) gene are common molecular abnormalities involved in mast cell tumorigenesis. KIT mutations often occur in dog, cat and human neoplastic mast cells and result in altered Kit protein structure and function. In dogs, certain KIT mutations are associated with more malignant and lethal disease. In contrast, KIT mutations in feline and human mast cell neoplasms are not correlated with prognosis, but are of value in diagnosis and treatment planning in humans. KIT genetic abnormalities have not been well investigated in other species, although aberrant cytoplasmic Kit protein staining detected in neoplasms of the ferret, horse and cow resembles aberrant Kit staining patterns detected in neoplastic mast cells of dogs, cats and humans. Mutations within KIT are classified as either regulatory‐type or enzymatic pocket‐type mutations according to their location within the KIT Proto‐Oncogene. Mutations within the enzymatic pocket domain confer tumour resistance to tyrosine kinase inhibitors (TKIs). Hence, knowledge of tumour KIT mutation status adds valuable information for optimizing patient treatment strategies. The use of TKIs in combination with conventional chemotherapeutics has opened a new treatment avenue for patients unresponsive to existing drugs. This review highlights the similarities and differences of mast cell neoplasia in mammals with a special focus on the involvement of KIT in the canine and feline forms in comparison to human mast cell neoplasia.

Concentration of extracellular vesicles isolated from blood relative to the clinical pathological status of dogs with mast cell tumours.

Extracellular vesicles (EVs) are membrane-enclosed fragments shed from all cell types, including tumour cells. EVs contain a wide range of proteins, biolipids and genetic material derived from mother cells and therefore may be potential biomarkers for tumour diagnosis, disease progression and treatment success. We studied the effect of canine mast cell tumours (MCTs) on EV concentrations in blood isolates in association with MCT's histological grade, Ki-67 proliferative index, KIT-staining pattern and number of PLT. The average EV concentration in blood isolates from nine dogs with MCTs was considerably higher than that in blood from eight healthy dogs. But there were no statistically significant differences in EVs concentration in the population of dogs with MCT according to a different histological grade of malignancy (Patnaik, Kiupel), KIT-staining pattern and Ki-67 proliferation index. The results show that these variables statistically do not significantly predicted EV concentrations in blood isolates (P > .05), except the KIT-staining pattern I which added statistically significantly to the prediction (P < .05). The results confirmed the impact of neoplasms on the morphological changes to cell membranes, which result in greater vesiculability and higher EV concentrations.

Caniene cutane mastceltumoren

Caniene cutane mastceltumoren (cMCT) zijn een vaak voorkomende neoplasie in de eerstelijnspraktijk. In 96% van de gevallen kunnen cMCT worden gediagnosticeerd via cytologie. Het stellen van een prognose is echter geen evidentie omwille van hun variabel biologisch karakter. Aan de hand van verschillende factoren, zoals tumorlocatie, de aanwezigheid van systemische klachten en metastasen, histologische en cytologische gradering, proliferatiemerkers, KIT-lokalisatiepatroon, KIT-mutatie en de tumorvrije randen, wordt de prognose ingeschat. De gekozen behandeling is gebaseerd op het resultaat van deze prognostische factoren, het klinisch stadium en de lokalisatie van de tumor. Mogelijke behandelingen zijn chirurgie, radiotherapie, chemotherapie, elektrochemotherapie, tyrosine-kinasereceptorinhibitor, cryotherapie en intraregionale behandeling met gedeïonizeerd water.

Investigating Associations Between Proliferation Indices, C-kit, and Lymph Node Stage in Canine Mast Cell Tumors.

Previous studies have evaluated cellular proliferation indices, KIT expression, and c-kit mutations to predict the clinical behavior of canine mast cell tumors (MCTs). The study purpose was to retrospectively compare mitotic index, argyrophilic nucleolar organizer regions (AgNORs)/nucleus, Ki-67 index, KIT labeling pattern, and internal tandem duplication mutations in c-KIT between stage I and stage II grade II MCTs. Medical records and tumor biopsy samples from dogs with Grade II MCTs with cytological or histopathological regional lymph node evaluation were included. Signalment, tumor location and stage, and presence of a recurrent versus de novo tumor were recorded. Mitotic index, AgNORs/nucleus, Ki-67, KIT staining pattern, and internal tandem duplication mutations in exon 11 of c-KIT were evaluated. Sixty-six tumors (51 stage I; 15 stage II) were included. Only AgNORs/nucleus and recurrent tumors were significantly associated with stage (odds ratio 2.8, 95% confidence interval [CI] 1.0-8.0, P = .049; odds ratio 8.8, 95% CI 1.1-69.5; P = .039). Receiver-operator characteristic analysis showed that the sensitivity and specificity of AgNORs/cell ≥ 1.87 were 93.3% and 27.4%, respectively, (area under the curve: 0.65) for predicting stage. Recurrent tumors and higher AgNORs/nucleus are associated with stage II grade II MCTs; however, an AgNOR cutoff value that reliably predicts lymph node metastasis was not determined.

Retraction Note to: Diagnostic procedures for improving of the KIT (CD117) expressed allele burden for the liver metastases from uterus mast cell tumors: prognostic value of the metastatic pattern and tumor biology.

The activating KIT marker plays a central role in the pathogenesis, diagnosis, and targeted treatment of systemic mastocytosis (SM). Recent studies have identified the KIT (CD117) as a marker that distinguishes nonneoplastic from neoplastic mast cells in human systemic mastocytosis. In this study, we conclude that immunohistopathology assays for KIT staining pattern are useful complimentary tools for diagnosis and evaluation of prognosis in uterus mast cell tumor (MCT) metastasis to the liver in 10 patients. Uterine and hepatic cytology revealed mast cell neoplasia, which was confirmed as visceral mast cell tumor on postmortem examination. Histological changes of densely packed, poorly differentiated neoplastic mast cells, sheets of neoplastic round to pleomorphic cells that formed nonencapsulated nodules, high mitotic figures, necrosis, and fibrosis were found. In addition, eosinophils were scattered among the mast cells at the periphery of the nodules. These findings indicate tumors of high-grade malignancy with infiltrative cells resembling the uterus MCT in the intraparenchymal and periparenchymal areas of the liver. Immunohistochemically, tumors were positive for KIT. The histopathologic features coupled with the KIT immunoreactivity led to diagnosis of high-grade uterus MCTs. Taken together, these findings suggest that CD117 may play a critical role in early uterus MCT development and may be a stimulatory factor in grade 3 MCT. Therefore, the result has supported our hypothesis that there was an increased opportunity to observe a higher CD117 staining pattern in high-grade MCTs.

Diagnostic procedures for improving of the KIT (CD117) expressed allele burden for the liver metastases from uterus mast cell tumors: prognostic value of the metastatic pattern and tumor biology.

The activating KIT marker plays a central role in the pathogenesis, diagnosis, and targeted treatment of systemic mastocytosis (SM). Recent studies have identified the KIT (CD117) as a marker that distinguishes nonneoplastic from neoplastic mast cells in human systemic mastocytosis. In this study, we conclude that immunohistopathology assays for KIT staining pattern are useful complimentary tools for diagnosis and evaluation of prognosis in uterus mast cell tumor (MCT) metastasis to the liver in 10 patients. Uterine and hepatic cytology revealed mast cell neoplasia, which was confirmed as visceral mast cell tumor on postmortem examination. Histological changes of densely packed, poorly differentiated neoplastic mast cells, sheets of neoplastic round to pleomorphic cells that formed nonencapsulated nodules, high mitotic figures, necrosis, and fibrosis were found. In addition, eosinophils were scattered among the mast cells at the periphery of the nodules. These findings indicate tumors of high-grade malignancy with infiltrative cells resembling the uterus MCT in the intraparenchymal and periparenchymal areas of the liver. Immunohistochemically, tumors were positive for KIT. The histopathologic features coupled with the KIT immunoreactivity led to diagnosis of high-grade uterus MCTs. Taken together, these findings suggest that CD117 may play a critical role in early uterus MCT development and may be a stimulatory factor in grade 3 MCT. Therefore, the result has supported our hypothesis that there was an increased opportunity to observe a higher CD117 staining pattern in high-grade MCTs.

Histologic Characteristics and KIT Staining Patterns of Equine Cutaneous Mast Cell Tumors

Mast cell tumors are uncommon in horses and typically have a benign clinical course, but there are occasional reports of more aggressive behavior. The objective of this study was to review histologic features and KIT expression patterns of 72 previously diagnosed equine cutaneous mast cell tumors to determine if either is associated with clinical outcomes. Biopsy specimens were reviewed using histologic criteria derived from grading schemes, and KIT antibody expression patterns used in canine tumors and surveys were sent to referring veterinarians for follow-up clinical data. Arabians were overrepresented relative to the reference population. Most tumors were well differentiated with low mitotic rates (96%), and aberrant KIT staining patterns, as described in dogs, were uncommonly identified (12%). Associated clinical disease was uncommon and no tumors exhibited malignant behavior. Overall, KIT staining pattern and histologic features were not associated with poor clinical outcome or abnormal tumor behavior.

The value of molecular expression of KIT and KIT ligand analysed using real‐time polymerase chain reaction and immunohistochemistry as a prognostic indicator for canine cutaneous mast cell tumours

This study investigated the correlation between KIT gene expression determined by immunohistochemistry and real-time polymerase chain reaction (RT-PCR) and the rate of tumour recurrence and tumour-related deaths in dogs affected with mast cell tumour (MCT). Kaplan-Meier curves were constructed to compare tumour recurrence and tumour-related death between patients. The log-rank test was used to check for significant differences between curves. KIT-I, KIT-II and KIT-III staining patterns were observed in 9 (11.11%), 50 (61.73%) and 22 (27.16%) tumours, respectively. Tumour recurrence rates and tumour-related deaths were not associated with KIT staining patterns (P = 0278, P > 0.05), KIT (P = 0.289, P > 0.05) or KIT ligand (P = 0.106, P > 0.05) gene expression. Despite the lack of association between KIT staining pattern and patient survival time, the results suggest a correlation between aberrant KIT localization and increased proliferative activity of MCTs. RT-PCR seems to be a sensible method for quantitative detection of KIT gene expression in canine MCT, although expressions levels are not correlated with prognosis.

Overexpression of P-glycoprotein, STAT3, phospho-STAT3 and KIT in spontaneous canine cutaneous mast cell tumours before and after prednisolone treatment

Prednisolone is a glucocorticoid (GC) commonly used in the treatment of canine mast cell tumours (MCTs); however, resistance to GCs develops in many MCTs following repeated treatment. P-glycoprotein (P-gp), signal transducer and activator of transcription 3 (STAT3) and KIT (CD117) are involved in GC resistance. The aim of this study was to evaluate the response to prednisolone treatment in canine cutaneous MCTs and to investigate the levels of P-gp, STAT3, phospho-STAT3 (pSTAT3) and KIT proteins in MCTs with or without prednisolone treatment. Immunohistochemistry was performed on tumour samples from 41 dogs with cutaneous MCTs. The overall objective response rate (including complete and partial responses) was 51.8% for dogs treated with prednisolone; poorly differentiated or higher stage MCTs had a lower response rate. The median time-span of tumours to reach maximal tumour regression was 14 d (range 3-77 d); 22 (81.5%) reached maximal regression at 21 d. The majority of MCTs overexpressed both P-gp and STAT3 before and after prednisolone treatment. Reduced expression of pSTAT3 and alterations in the KIT expression pattern were observed in MCTs post-treatment. Prednisolone treatment that caused a marked reduction in tumour volume was correlated with reduced pSTAT3 expression. A cytoplasmic KIT staining pattern was correlated with a lower tumour response rate to prednisolone treatment.

Canine Cutaneous Mast Cell Tumor: Biologic Behavior and Its Correlation with Prognostic Indicators

Cutaneous mast cell tumor (MCT) shows a variable biological behavior in dogs and may present either as solitary masse that can be treated and cured with surgical removal or as a systemic metastatic and fatal disease. Histological grade, KIT pattern and proliferative index are typically prognostic factors in MCTs. In the present study, we have investigated correlation between clinical data (breed, age, gender, tumour location, tumor size, time before surgery, number of tumours, occurrence of metastasis and recurrence), cellular proliferation (Ki-67, mitotic index), intratumoural microvessel density (IMVD) and apoptotic index with the histological grade and KIT pattern. 28 tumors, from 20 dogs with cutaneous MCT were evaluated. There was association between histological grade, IMVD, tumor ulceration and number of tumors. A significant increase of Ki-67 expression and mitotic index was observed in MCTs with cytoplasmic KIT staining pattern. Patnaik histological grade system was related to mitotic index. Histological grade in canine cutaneous MCT should not be assessed as the only prognostic factor, but associated with KIT pattern, IMDV, cellular proliferation, presence of tumour ulceration, number of tumours, recurrences and metastases.

C-KIT messenger RNA and protein expression and mutations in canine cutaneous mast cell tumors

Cutaneous mast cell tumors (MCTs) are among the most common neoplasms in dogs and show a highly variable biologic behavior. Histological grading, cell proliferation markers, and KIT immunohistochemistry are typically used to predict post-surgical prognosis. In the present study, c-KIT messenger RNA (mRNA) expression was measured in canine MCTs and its relationship with tumor grade, immunohistochemical staining pattern, post-surgical prognosis, and mutations was investigated. A significant increase of c-KIT mRNA was observed in MCTs versus healthy skin and surgical margins. Mutations were observed in 8.3% of cases. The KIT staining pattern was investigated for both grading systems. In particular, staining pattern III was associated with grade II (G2) and G3 MCTs, while staining patterns I and II were associated with G1 and G2 MCTs. Considering the 2-tier histological grading, the high grade was mainly associated with pattern III (71%) while the low grade was associated with patterns II (70%) and I (28%). A weak association between the KIT staining pattern and outcome was also observed. The results obtained suggest that c-KIT mRNA is overexpressed in canine MCT, although the fold variations were not associated with the protein localization or complementary DNA mutations. These observations suggested that the 3 events were independent. The histological grading and the KIT staining pattern have prognostic value as previously published. Staining pattern I could be especially helpful in predicting a good prognosis of G2 MCTs. Sequence mutations were not necessarily suggestive of a worse prognosis, but might be useful in choosing a chemotherapy protocol.

Evaluation of prognostic markers for canine mast cell tumors treated with vinblastine and prednisone

BackgroundCanine cutaneous mast cell tumor (MCT) is a common neoplastic disease associated with a variable biologic behavior. Surgery remains the primary treatment for canine MCT; however, radiation therapy (RT) and chemotherapy are commonly used to treat aggressive MCT. The goals of this study were to evaluate the prognostic utility of histologic grade, c-KIT mutations, KIT staining patterns, and the proliferation markers Ki67 and AgNORs in dogs postoperatively treated with vinblastine and prednisone +/- RT, and to compare the outcome of dogs treated with post-operative chemotherapy +/- RT to that of a prognostically matched group treated with surgery alone. Associations between prognostic markers and survival were evaluated. Disease-free intervals (DFI) and overall survival times (OS) of dogs with similar pretreatment prognostic indices postoperatively treated with chemotherapy were compared to dogs treated with surgery alone.ResultsHistologic grade 3 MCTs, MCTs with c-KIT mutations, MCTs with increased cytoplasmic KIT, and MCTs with increased Ki67 and AgNOR values were associated with decreased DFI and OS. Dogs with histologic grade 3 MCT had significantly increased DFI and OS when treated with chemotherapy vs. surgery alone. Although not statistically significant due to small sample sizes, MCTs with c-KIT mutations had increased DFI and OS when treated with chemotherapy vs. surgery alone.Conclusion and clinical importanceThis study confirms the prognostic value of histologic grade, c-KIT mutations, KIT staining patterns, and proliferation analyses for canine MCT. Additionally, the results of this study further define the benefit of postoperative vinblastine and prednisone for histologic grade 3 MCTs.

KIT and RCC Are Useful in Distinguishing Chromophobe Renal Cell Carcinoma From the Granular Variant of Clear Cell Renal Cell Carcinoma

The distinction between chromophobe renal cell carcinoma, the granular cell variant of clear cell renal cell carcinoma, and renal oncocytoma is a common diagnostic dilemma. The usefulness of KIT, CD10, RCC, and RON in the differential diagnosis of these renal epithelial tumors was investigated. KIT was 100% positive in chromophobe renal cell carcinoma (11 of 11) and renal oncocytoma (12 of 12). The KIT staining pattern was identical in both tumor types, with cytoplasmic membrane attenuation, and fine granular cytoplasmic staining. In contrast, KIT was absent in all granular cell variants of clear cell renal cell carcinoma (0 of 6). RCC was observed in more than 80% of the granular cell variant of clear cell renal cell carcinoma (5 of 6) but was negative in all chromophobe renal cell carcinomas (0 of 11) and renal oncocytomas (0 of 12). CD10 was expressed in 100% of the granular cell variant of clear cell renal cell carcinoma (6 of 6), 72% of chromophobe renal cell carcinomas (8 of 11), and 58% of renal oncocytomas (7 of 12). RON was 100% positive in the chromophobe renal cell carcinomas (11 of 11) and renal oncocytomas (12 of 12) but only 50% positive in the granular cell variant of clear cell renal cell carcinoma (3 of 6). Colloidal iron was diffusely and strongly positive in more than 80% of the chromophobe renal cell carcinomas (9 of 11), focally and weakly positive in 41% of the renal oncocytomas (5 of 12) but negative in all granular cell variant of clear cell renal cell carcinoma (0 of 6). The above results demonstrate that: 1) KIT is a very sensitive marker for both chromophobe renal cell carcinoma and renal oncocytoma; 2) immunohistochemistry using antibodies to KIT combined with RCC was sufficient to discriminate between chromophobe renal cell carcinoma and the granular cell variant of clear cell renal cell carcinoma; and 3) neither RON, nor KIT, nor a combination of this panel can be used to distinguish chromophobe renal cell carcinoma from renal oncocytoma. Colloidal iron staining aided in this distinction for the majority of the chromophobe renal cell carcinomas (more than 80% positive) and renal oncocytomas (close to 60% negative).

The use of KIT and tryptase expression patterns as prognostic tools for canine cutaneous mast cell tumors.

Cutaneous mast cell tumors (MCTs) are one of the most common tumors in dogs. Currently, prognostic and therapeutic determinations for MCTs are primarily based on the histologic grade of the tumor, but a vast majority of MCTs are of an intermediate grade, and the prognostic relevance is highly questioned. A more detailed prognostic evaluation, especially of grade 2 canine MCTs, is greatly needed. To evaluate the prognostic significance of KIT and tryptase expression patterns in canine cutaneous MCTs, we studied 100 cutaneous MCTs from 100 dogs that had been treated with surgery only. The total survival and disease-free survival time and the time to local or distant recurrence of MCTs were recorded for all dogs. Using immunohistochemistry, 98 of these MCTs were stained with anti-KIT and antitryptase antibodies. Three KIT- and three tryptase-staining patterns were identified. The KIT-staining patterns were identified as 1) membrane-associated staining, 2) focal to stippled cytoplasmic staining with decreased membrane-associated staining, and 3) diffuse cytoplasmic staining. The tryptase-staining patterns were identified as 1) diffuse cytoplasmic staining, 2) stippled cytoplasmic staining, and 3) little to no cytoplasmic staining. Based on univariate and multivariate survival analysis, increased cytoplasmic KIT staining was significantly associated with an increased rate of local recurrence and a decreased survival rate. The tryptase-staining patterns were not significantly associated with any survival parameter. On the basis of these results, we propose a new prognostic classification of canine cutaneous MCTs, according to their KIT-staining pattern, that can be used for the routine prognostic evaluation of canine cutaneous MCTs.

Ultrasonic relaxation of hydrate melts: system Ca(NO 3) 2·4H 2O : Petrucci, S. and Fittipaldi, F. Journal of the Acoustical Society of America, 42, No 2, p 517 (August 1967)

An 8-year-old neutered male French Bulldog was presented with a 2-day history of intermittent vomiting, reduced appetite and recent rapid development of multiple cutaneous masses over the head and neck regions. On presentation, the patient had a moderate volume of pericardial and bilateral pleural effusion. Echocardiography demonstrated irregular, heterogeneous thickening of the walls of the right ventricle and right atrium, consistent with infiltrative intramyocardial disease. Cytological examination of fine needle aspirates from one of the cutaneous masses confirmed a mast cell tumour. Pericardial fluid analysis revealed a haemorrhagic neoplastic effusion due to mast cell neoplasia. Histopathological and immunohistochemical examination of tissues obtained post mortem confirmed a high-grade cutaneous mast cell tumour with metastasis to the heart, pericardium, mediastinum and spleen. No metastatic disease was present in the submandibular lymph nodes or liver. Immunohistochemistry demonstrated KIT staining pattern 2. There was strong nuclear Ki67 labelling in an average of 65.0 cells per grid and an average of three positive AgNORs per nucleus in neoplastic cells. Polymerase chain reaction for the activating duplication mutation in exons 8 and 11 of c-Kit were negative. To the authors’ knowledge, this is the first report of a canine cutaneous mast cell tumour associated with neoplastic pericardial effusion and widespread intrathoracic metastasis.