The prognostic value of lymph node metastasis with grade 2 MCTs in dogs: 55 cases (2001-2010).

This study evaluates a series of dogs diagnosed with grade 2 cutaneous mast cell tumors (MCTs) with concurrent lymph node (LN) metastasis. All dogs had surgical excision of the primary tumor. The presence of metastasis was confirmed with either histopathology (n = 35) or cytology (n = 20). There was no significant difference in survival times (STs) between dogs with and without LN metastasis. Median survival time (MST) was not reached at 65.9 mo. LN palpation was a poor predictor of metastasis (sensitivity, .71; specificity, .54). Tumor location was the only prognostic factor for survival in this series of dogs. ST was greater for dogs that had removal of their metastatic LN. This study suggests that in dogs with grade 2 MCTs, outcome may not be affected by the presence of LN metastasis; however, removal of the metastatic LN may prolong survival.

Correlation of ultrasound findings, liver and spleen cytology, and prognosis in the clinical staging of high metastatic risk canine mast cell tumors.

Cytologic sampling of the ultrasonographically normal spleen and liver is not implemented routinely in the clinical staging of canine cutaneous mast cell tumors and normal ultrasound findings are often accepted as sufficient evidence for ruling out splenic or liver metastasis. Our objective was to define the specificity and sensitivity of ultrasound findings for diagnosis of mast cell infiltration when verified with cytologic evaluation, and to define the prognostic role of cytologic evaluation of liver and splenic aspirates. Dogs with a diagnosis of clinically aggressive grade II, or grade III mast cell tumor treated with a combination vinblastine/CCNU chemotherapy protocol, were selected retrospectively based on availability of cytologic evaluation of spleen plus or minus liver for staging. Out of 19 dogs, 10 dogs had a grade II tumor and nine a grade III tumor. Seven dogs had mast cell infiltration of the spleen, liver, or both. The sensitivity of ultrasound for detecting mast cell infiltration was 43% for the spleen and 0% for the liver. Dogs with positive cytologic evidence of mast cell infiltration to spleen, liver, or both had significantly shorter survival (100 vs. 291 days) than dogs without evidence of mast cell infiltration (P<0.0001). Routine splenic aspiration should be performed regardless of ultrasonographic appearance in dogs with a clinically aggressive mast cell tumor.

Ultrasound-guided cytology of spleen and liver: a prognostic tool in canine cutaneous mast cell tumor.

BACKGROUND: In the clinical staging of cutaneous mast cell tumors (cMCT), the diagnosis of metastasis is controversial based on cytological examination of lymph nodes, spleen, liver, bone marrow, and blood. OBJECTIVES: To define the prognostic role of ultrasound-guided cytology of spleen and liver in cMCT. The results of cytological evaluation were compared in relation with survival time. ANIMALS: Fifty-two client-owned dogs with a diagnosis of cMCT. METHODS: Selection of cases was based on cytological evaluation of liver and spleen to detect infiltration at distant sites. The Kaplan Meier method was used to compare survival in dogs with and without infiltration of spleen and liver (log-rank test P < .05). RESULTS: Ten dogs with cMCT had mast cell infiltration of spleen, liver, or both and 4 of these dogs had involvement of the regional lymph nodes. The majority of dogs had 2 or more ultrasonographically abnormal findings simultaneously in spleen and liver. Nine dogs had grade II cMCT, and 1 had grade III cMCT. Dogs with positive evidence of mast cell infiltration to spleen, liver, or both had shorter survival times (34 versus 733 days) compared with dogs negative for mast cell infiltration at distant sites. CONCLUSION AND CLINICAL IMPORTANCE: Dogs with evidence of mast cell infiltration at distant sites have a shorter survival times than dogs without evidence of infiltration at distant sites. This study suggests that cytology of spleen and liver is indicated either for ultrasonographically normal or for ultrasonographically abnormal spleen and liver in dogs with cMCT.

Metastatic mast cell tumour in a dog presenting with spinal pain.

The clinical, advanced imaging and surgical features of a case of canine extradural mast cell tumour are presented. This rare location has only been reported once before as a primary lesion, although the present case may be a metastatic lesion. Given the frequent occurrence and treatment of cutaneous mast cell tumours in dogs, the finding of spinal metastasis is an important reminder to consider metastatic neoplasia in cases of previously treated cancers presenting with spinal pain.

Nucleomorphometric analysis of canine cutaneous mast cell tumours.

Thirty-five canine cutaneous mast cell tumours (CCMCTs) were analysed by computerized nuclear morphometry. In each case, the nuclei of at least 100 neoplastic cells were measured, and the mean nuclear area (MNA), mean nuclear perimeter (MNP) and mean nuclear form factor (FF) were calculated. Significant differences in respect of MNA and MNP occurred between tumours of grades I and III and between those of grades II and III (P<0.01) but not between tumours of grades I and II (P>0.01). No significant differences in respect of FF were observed between tumours of different grades. The results obtained indicate that nuclear morphometric analysis may assist in the grading of CMCTs.

Results of radiation therapy in 19 dogs with cutaneous mast cell tumor and regional lymph node metastasis.

The records of 19 dogs with cutaneous mast cell tumor and regional lymph node metastasis (WHO Stage 2) were reviewed to determine the efficacy of radiation therapy in this population. Dogs with grade I (n = 1), grade II (n = 16), and grade III (n = 2) cutaneous mast cell tumor were included in this study. All dogs were treated with a combination of pre-irradiation surgical cytoreduction of the primary tumor, irradiation of the primary tumor and regional lymph node, and oral prednisone. Total radiation dose to the primary tumor and regional lymph node ranged from 48 to 57 Gray (Gy). The medial iliac and hypogastric lymph nodes were irradiated prophylactically in 11 dogs with primary tumor of the pelvic limb and positive ipsilateral popliteal lymph node. Total radiation dose to these lymph nodes ranged from 48 to 57 Gy. For all radiation fields, dose per fraction was 3 Gy, and therapy was administered on a Monday through Friday schedule. Acute and late radiation side effects observed in this study were considered acceptable. The median disease-free survival was 1,240 days (95% confidence interval 256 to 2,391 days). The disease-free survival in dogs with stage 2 mast cell tumor suggests that the combination of surgery, irradiation, and prednisone for the primary tumor along with irradiation of the positive lymph node is effective.

Recurrence rates and sites for grade II canine cutaneous mast cell tumors following complete surgical excision.

A retrospective study was performed on 31 dogs with completely excised, grade II, cutaneous mast cell tumors in order to determine recurrence rates and sites. Distant tumor recurrence developed in 22% of dogs, and local tumor recurrence developed in 11% of dogs; however, the vast majority of these animals were incompletely staged initially. Complete surgical excision of grade II mast cell tumors was associated with effective local control in 89% of these dogs. Therefore, adjuvant radiation therapy might not be indicated in the majority of dogs with complete surgical excision.

Progressive neurological signs associated with systemic mastocytosis in a dog.

A 9-year-old dog was presented with nonregenerative anaemia and severe thrombocytopenia, diarrhoea, spinal hyperalgesia and progressive hindlimb paresis. A moderately well differentiated cutaneous mast cell tumour (MCT) was removed from the skin of the right elbow along with the enlarged right prescapular lymph node. Due to deterioration of the dog's neurological condition, euthanasia was performed. On necropsy examination, haemorrhage and accumulations of poorly differentiated mast cells were found in the lumbosacral region and cauda equina. This article describes an unusual presentation of systemic mastocytosis and the previously unreported finding of metastasis of mast cells to the spinal cord.

Radiation therapy for incompletely resected canine mast cell tumors.

The records of 56 dogs treated with megavoltage radiation for mast cell neoplasia were reviewed to determine the efficacy of this treatment modality. Total radiation dose ranged from 45 to 57 Gray (Gy), dose per fraction ranged from 3.0 to 4.0 Gy, and radiation treatment time ranged from 14-28 days. Median disease free interval (95% CI) was 32.7 (19-70) months. Median disease free interval for dogs older than 7.5 years was 15 (lower limit 7) months as compared to 62 (lower limit 20) for dogs younger than 7.5 years of age (p = 0.006). Median disease free interval for dogs with measurable disease was 12 (lower limit 5) months as compared to 54 (32-70) months for dogs with microscopic disease (p = 0.006). Radiation treatment time was also significantly related to disease free interval. Median disease free interval for dogs treated longer than 22 days was 12 (7-19) months as compared to greater than 50 (lower limit 20) months for dogs treated in 22 or fewer days (p < 0.001). This appeared to be due to more recurrences in dogs treated with 3-per-week fractionation and suggests that tumor proliferation in the interfraction interval may be important. Sex, tumor location, histologic grade, WHO clinical stage, number of radiation fractions, total radiation dose, and dose-per-fraction, as well as the following "yes/no" variables: steroids given, surgery prior to radiation, lymph nodes irradiated, and development of another mast cell tumor did not appear to influence median disease free interval or survival. Data presented herein support megavoltage radiation as an effective treatment for canine mast cell neoplasia, and suggest that disease free interval in dogs treated with daily fractions may be longer than that achieved with alternating day fractions.

Effect of cytokines on tumour cell-endothelial interactions.

The adherence of tumour cells to microvascular endothelium is believed to be a necessary step in their migration to sites of metastasis. It has been proposed that this process occurs when cell surface molecules on tumour cells bind to complementary sites on endothelial cells. The expression of these endothelial-derived cell adhesion molecules appears to be modulated by cytokines, a broad class of protein mediators which play important roles in immune and inflammatory reactions. It has been found by ourselves and others that exposure of endothelium to some cytokines augments the adhesion of inflammatory cells as well as tumour cells in in vitro assays. We used a murine model consisting of P815 mastocytoma cells and microvascular endothelium and found that pretreatment of endothelial monolayers with TNF-alpha, IL-1, LPS or PMA augmented the number of tumour cells that attach in a dose-dependent fashion. FACS analysis showed that the change in binding was due to an increase in the expression of VCAM-1 on the surface of the endothelial cell. Methylxanthines (caffeine and theophylline) as well as "classical" calcium-mobilizing agents (ionomycin and thapsigargin) inhibited the expression of VCAM-1 in MME. We also studied the possible mechanisms of TNF-alpha signal transduction in endothelial cells. We examined the involvement of protein kinases in the TNF-alpha effect. Although we found that inhibitors of PKC could inhibit the TNF-alpha effect, our studies suggest that the "classical" PKC pathway is not completely responsible for signaling since TNF-alpha did not cause translocation of PKC to the cell membrane and its effect could not be completely mimicked by PMA. We also studied the effect of TGF-beta on the binding of tumour cells to endothelium. Exposure of endothelium to TGF-beta led to the inhibition of both basal and TNF-alpha enhanced binding of P815 cells. Inhibitors of G-proteins do not abolish TGF-beta action, and PKC and PKA activators elicit an opposite effect. However, TGF-beta-mediated inhibition of both basal binding and TNF-alpha-enhanced P815 binding to endothelium is completely abolished in the presence of the protein phosphatase inhibitor okadaic acid suggesting that TGF-beta elicits its effect by stimulating protein phosphatase activity.

Differential production of interleukin-6 and its close relation to liver metastasis in clones from murine P815 mastocytoma.

Interleukin-6 (IL-6)-producing abilities of plastic-adherent and plastic-non-adherent P815 clones were investigated in connection with the liver metastasis. Most adherent clones produced IL-6 at high level (over 10 ng/10(5) cells per 48 h), and they coincided with highly liver-metastatic clones. The remaining adherent and all the non-adherent clones tested produced IL-6 at low level (under 1.5 ng/10(5) cells), and they coincided with the low or non-liver-metastatic clones. The IL-6 production was greatly enhanced by IL-1 alpha, but not by IL-6, tumor necrosis factor-alpha or interferon-gamma.

Correlation of DNA ploidy to tumor histologic grade, clinical variables, and survival in dogs with mast cell tumors.

By using flow cytometry, a retrospective analysis of the DNA content of 40 primary canine mast cell tumors and seven lymph nodes that contained metastatic mast cell tumor from 44 dogs of various breed, sex, and age was performed on formalin-fixed, paraffin-embedded samples of the tumors and nodes. These samples were chosen according to the following criteria: samples contained sufficient well-preserved tumor tissue in the paraffin block for processing, sufficient patient history data were available, clean and homogeneous cell suspensions were obtained after processing, and interpretable DNA histograms were produced on analysis. The ploidy data obtained were compared with the histopathologic grade, the anatomical site of occurrence, the clinical stage of the tumors, and the survival of the dogs. Over 70% (29/40) of the mast cell tumors were diploid. Three metastatic mast cell tumors in lymph nodes had the same ploidy status as their corresponding primary tumors. In five dogs, mast cell tumors from multiple sites in each dog displayed similar ploidy status. Of 26 dogs evaluated for survival times, 69% (18/26) had diploid tumors and 31% (8/26) had aneuploid tumors. When numbers of diploid versus aneuploid tumors were compared, no significant difference was found between any two grades, clinical stages, or anatomic sites. A significant difference (P = 0.02) was found, however, between aneuploid and diploid tumors when comparing Stage I and non-Stage I disease. The Kaplan-Meier survival plot indicated a tendency towards an increased survival within the first year in dogs with diploid versus aneuploid tumors (P = 0.06).

An expansile secondary hypophyseal mastocytoma in a dog.

A 5-year-old mixed breed dog was presented with a history of depression and anorexia. Physical examination revealed a pharyngeal tumour and a neurological examination indicated the presence of a possible space-occupying lesion in the brain. Investigative procedures included a bloodsmear, impression smears and cytology of the pharyngeal tumour, haematology, chemical pathology, faecal analysis, urinalysis, electrocardiography, cerebrospinal fluid analysis, hormone assays and a computerised axial tomography scan. Results of these investigations revealed a round cell tumour in the pharynx, hypergammaglobulinaemia (34 g l-1), azotaemia (urea 8.6 mmol l-1 and creatinine 170 mumol l-1), hypoalbuminaemia (20 g l-1), proteinuria, sinus bradycardia (heart rate 60 beats per min), increased concentration of protein in the CSF (1.1 g l-1), hypoadrenocorticism (base line cortisol less than 55 nmol l-1) and hypothyroidism (T4 less than 13 nmol l-1). The computerised axial tomography scan revealed a brain tumour in the region of the hypophysis. The dog was euthanased and a post mortem examination confirmed the presence of a pharyngeal tumour with apparent direct extension of the tumour into the brain. Both tumours were confirmed histologically as mastocytomas.

Immune rejection of metastases arising from intraocular tumors in mice.

The role of the immune response in the elimination of spontaneous metastases arising from intraocular tumors was examined in a syngeneic intraocular murine tumor model. P91 mastocytoma (DBA/2 origin) expresses strong tumor-specific transplantation antigens and grows transiently in the eyes of syngeneic hosts before undergoing spontaneous rejection. An organ culture technique was used to detect spontaneous metastases in the lungs, spleens, brains, and thymuses of intraocular tumor-bearing mice. Metastatic tumor cells were detected in all organs of immunodeficient mice (i.e., athymic, nude, or x-irradiated DBA/2 mice) within 14 days of intraocular transplantation, and grew progressively thereafter. By contrast, metastatic tumors were rejected in 100% of the immunocompetent DBA/2 mice examined on day 15. Timed enucleation experiments demonstrated that the immune rejection of disseminated tumor cells occurred within 24-48 hr of their arrival at the various organs. The immune rejection of spontaneous metastases could be adoptively transferred to immunodeficient tumor-bearing mice using spleen cells, but not immune serum, from intraocular tumor-bearing immunocompetent donors. Selective cell depletion experiments revealed that the immune spleen cell effecting immunity was an Lyt 1+, 2+ T cell. The results indicate that the immune rejection of the spontaneous metastases arising from primary intraocular tumors is a T cell-dependent, radiosensitive process that rapidly eliminates metastases within the lungs, brain, thymus, and the spleen of the immunocompetent host.

Proliferative patterns of lymphocytes in lymph nodes during tumour development: involvement of T and B cell areas.

DNA-synthetizing lymphocytes were identified in the lymph nodes regional and more distal to the site of developing P-815 tumours by incorporation of [3H]-thymidine followed by autoradiography of lymph node sections. It appeared that not only T but also B cell areas of draining and to a lesser extent of distal lymph nodes were stimulated by the growing tumour. This result was unexpected since neither humoral nor tumour cell-bound antibody could be identified so far as a functional correlate of B cell stimulation. In general the proliferative response of lymphocytes followed a biphasic pattern with an early peak of reactivity on days 2-3 and a second peak around day 12-15 after tumour cell inoculation. In the draining (axillary) lymph node the second peak of reactivity was suppressed, possibly as a consequence of metastatic tumour cells in this node when tumour cells were inoculated in the flank. The pattern of lymphocyte stimulation revealed larger individual variations after tumour cell inoculation in the flank than the foot pad. These results were associated with a slower and less regular drainage of carbon particles from the flank to the axillary and exceptionally the brachial lymph node than from the foot pad to the popliteal node after injection of India ink.