Effect of Cortisone on Mast Cell Tumors (Mastocytoma) of the Dog

Genetic Changes in Mastocytes and Their Significance in Mast Cell Tumor Prognosis and Treatment

Mast cell tumors are a large group of diseases occurring in dogs, cats, mice, as well as in humans. Systemic mastocytosis (SM) is a disease involving the accumulation of mast cells in organs. KIT gene mutations are very often seen in abnormal mast cells. In SM, high KIT/CD117 expression is observed; however, there are usually no KIT gene mutations present. Mastocytoma (MCT)-a form of cutaneous neoplasm-is common in animals but quite rare in humans. KIT/CD117 receptor mutations were studied as the typical changes for human mastocytosis. In 80% of human cases, the KIT gene substitution p.D816H was present. In about 25% of MCTs, metastasis was observed. Changes in the gene expression of certain genes, such as overexpression of the DNAJ3A3 gene, promote metastasis. In contrast, the SNORD93 gene blocks the expression of metastasis genes. The panel of miR-21-5p, miR-379, and miR-885 has a good efficiency in discriminating healthy and MCT-affected dogs, as well as MCT-affected dogs with and without nodal metastasis. Further studies on the pathobiology of mast cells can lead to clinical improvements, such as better MCT diagnosis and treatment. Our paper reviews studies on the topic of mast cells, which have been carried out over the past few years.

Treatment of multiple synchronous canine mast cell tumours using intratumoural tigilanol tiglate

Mast cell tumours (MCTs) are common canine skin neoplasia. While they generally occur as single tumours, multiple synchronous MCTs (msMCTs) of de novo/non-metastatic origin are reported in a proportion of the patient population. Where there is no evidence of metastasis or lymphatic spread, MCTs are effectively controlled by surgery and other local therapies. However, treatment of de novo msMCTs can be more challenging, especially when they occur in surgically difficult locations. Here, we report the use of tigilanol tiglate, a novel small molecule registered as a veterinary pharmaceutical for the local treatment of non-metastatic MCTs, in the treatment of patients with msMCTs presenting at three Australian specialist referral centres. We also present a meta-analysis of the literature to provide a better understanding of the prevalence of canine msMCTs. Notably, nine patients with a total of 32 MCTs were treated during the study. A complete response was recorded in 26 (81%) of the individual MCTs on Day 28 after a single tigilanol tiglate injection. Of the 6 initially non-responsive MCTs, one achieved a complete response after a further tigilanol tiglate treatment. A complete response was reported at 6 months in all 22 of the tumours that were evaluable and that had recorded a complete response at Day 84. For the literature meta-analysis, 22 studies were found with prevalence estimates of msMCTs ranging from 3 to 40%; when combined, these studies yielded 3,745 patients with a prevalence of 13% (95% CI 10; 16). Overall, the results demonstrate the utility of intratumoural tigilanol tiglate as an option for the treatment of multiple MCTs where multiple surgical resections would have been required.

Evaluation of Histological, Immunohistochemical, Clinical and Genetic Prognostic Factors Associated with the Response of Canine Mast Cell Tumours to Glucocorticotherapy

Mast cell tumours (MCTs) are one of the most frequent neoplasms in dogs. Glucocorticoids (GCs) are widely used in the management of this disease, although no guidelines for their use have been established. The aim of this study was to evaluate the correlation of MCT prognostic factors with measurable response to GCs. This retrospective study included 60 dogs treated with prednisone or prednisolone prior to surgical biopsy of MCT. Incisional or excisional biopsy was performed 7-14 days after initiation of GC therapy. Histopathology, immunohistochemical labelling for Ki67 and KITr, and polymerase chain reaction for the c-KIT gene were performed. Partial response occurred in 63.3% of cases (38/60), while 36.7% (22/60) did not respond. A response to GCs was correlated with lower stage of the disease, low histological grade, lower pattern of KITr expression and Ki67 score. Response to GCs was positively correlated with well-established favourable prognostic factors.

Canine Mastocytoma

Utilizing a modified capillary tube technique, analysis revealed a significantly higher mean blood coagulation time in a group of 14 dogs with mastocytoma when compared to the mean coagulation time of 70 non-mastocytoma dogs. In dogs with mastocytoma, approximately one third had intermediate size tumors and a prolonged mean coagulation time and two thirds had a mean coagulation time that did not differ significantly from the mean of the non-mastocytoma dogs. Evidence for heparin release and possible heparin inactivating mechanisms is reviewed.

Cancer chemotherapy: an annotated history

Treating cancer with drugs is an ancient art, but it is from discoveries made during and after the Second World War that real clinical success with cancer chemotherapy has occurred. Human and veterinary cancer chemotherapy have coevolved in the context of fascinating historical, political, and scientific events created by equally fascinating individuals.

Clinical stable systemic mastocytosis with interferon alpha-2b therapy

Systemic mastocytosis (SM) with progressive infiltration of various organs by mast cells is a rare disease with a mean survival of 2 years. So far there is no established therapy. We describe a patient with progressive mastocytosis who had a clinical response to interferon alpha-2b 3 x 5 Mio U s.c. three times a week. The response is stable 3 years after initiation of therapy and includes reduction of abdominal lymphadenopathy, ascites, decrease of serum and urinary histamine levels as well as pulmonary reticulonodular markings.

Mast cell tumors: dilemmas of diagnosis and treatment

Making the most appropriate choices for diagnosis and treatment of canine and feline mast cell tumors remains challenging. An understanding of the heterogeneity of the disease process, the associated paraneoplastic disorders, and the known prognostic indicators can be helpful in making rational decisions regarding each individual case. A multimodality approach may be needed for optimal care of some patients, but the effectiveness of current medical treatment strategies continues to limit our ability to cure disseminated forms of disease.

Determination of the lethal dose of dexamethasone for early passage in vitro human glioblastoma cell cultures

Previous investigators have supported the idea that glucocorticoids may be oncolytic. In this study, the percentage of cell death in two human glioblastoma cell cultures was related to the concentration of dexamethasone that was administered. It was determined that for Cell line 1, the median lethal dose was approximately 500-800 micrograms/ml and the completely lethal dose was about 900-1000 micrograms/ml; the 3H-thymidine uptake to approximate the mitotic rate was 16,607 cpm, and the dexamethasone receptor activity was 228 fmol/mg protein. The median lethal dose and completely lethal dose for Cell line 2 was approximately 500-600 micrograms/ml and 700-1000 micrograms/ml, respectively; the 3H-thymidine uptake was 8402 cpm, and the dexamethasone receptor activity was 137 fmol/mg protein. These lethal concentrations of dexamethasone are probably higher than can be tolerated by systemic delivery. However, it remains to be seen whether the interstitial administration of dexamethasone could achieve local concentrations resulting in the oncolysis of malignant gliomas. The clinical significance of these findings will depend on the local tolerance of normal brain parenchyma to very high doses of dexamethasone. A review of some of the literature is included.

Canine mast cell tumors

Despite the fact that the mast cell tumor is a common neoplasm of the dog, we still have only a meager understanding of its etiology and biologic behavior. Many of the published recommendations for treatment are based on opinion rather than facts derived from careful studies and should be viewed with some skepticism. Because of the infrequent occurrence of this tumor in man, only a limited amount of help can be expected from human oncologists; therefore, burden of responsibility for progress in predicting behavior and developing treatment effective for canine mast cell tumors must fall on the shoulders of the veterinary profession.

The spectrum of mastocytosis

Mastocytosis represents a spectrum of clinical disorders that results from an aberrant proliferation of tissue mast cells. This disease process may be confined to the skin (cutaneous mastocytosis) or may involve multiple organs (systemic mastocytosis). Parameters that are useful in differentiating cutaneous from systemic disorders include patient age, symptom complex, and clinical signs. A wide range of clinical symptoms may be encountered in patients with mastocytosis which result from the release of pharmacologically potent mast cell mediators. Distinct cutaneous patterns resulting from skin mast cell infiltrates can be helpful in identifying patients with systemic involvement. The diagnosis of mastocytosis is confirmed by demonstrating increased tissue mast cells in involved organs. The overall prognosis for patients with proliferative mast cell disease is relatively good, although a small percentage are at risk for developing a fatal neoplastic disorder (malignant mastocytosis). Treatment of mastocytosis is directed at both inhibiting mast cell degranulation and blocking the potential systemic effects of released secretory products. Future therapeutic advances depend upon an improved understanding of the basic mechanisms involved in mast cell mediator release and the forces that govern mast cell growth and development.

Pathologic report of 29 necropsies on dogs with mastocytoma

At necropsy 28 of 29 dogs with cutaneous mastocytoma had internal accumulations of mast cells in various organs. The order of decreasing incidence in these organs was: regional lymph nodes, spleen, liver, bone marrow, kidneys, lungs, and heart. No correlation was obvious between the size of the external lesions and the extent of internal involvement. A good correlation existed between the degree of anaplasia of the initial external tumor and the extent of subsequent internal involvement. Other significant lesions observed in these dogs included a diffuse plasmacytosis and a chronic focal glomerulitis. The distribution of neoplastic mast cells in some dogs inferred a multicentric origin. The possibility of an autoimmune reaction in these dogs is briefly discussed.

Mast cells in the circulatory system of man

This report is based upon a study of multiple segments of the cardiovascular system of 200 deceased persons and selected surgical specimens. Mast cells are present in the adventitia of all blood vessels. Only the largest vessels have mast cells in the intima and subintima as well. In this location the number of mast cells is highest in grossly normal but microscopically edematous areas. Mast cells are rarely present in early and are never present in advanced atheromatous lesions. The theory is advanced that mast cells are attracted by plasma insudate to release heparin for degradation of lipoproteins. Thus, mast cells might play a role in atherogenesis.