A retrospective study on prophylactic regional lymphadenectomy versus nodal observation only in the management of dogs with stage I, completely resected, low-grade cutaneous mast cell tumors.

BACKGROUND: While lymphadenectomy of metastatic lymph nodes (LNs) has been associated with improved outcome, the clinical utility of prophylactic lymphadenectomy in dogs with stage I cutaneous mast cell tumors (cMCTs) remains a controversial topic. To assess the therapeutic role of lymphadenectomy of uninvolved regional LNs, the long-term outcome of cMCT-bearing dogs with cytologically negative and surgically unresected regional LNs (observation only, OO) was compared with that of dogs with surgically resected and histologically negative regional LNs (prophylactic regional lymphadenectomy, PRL). RESULTS: A retrospective analysis of 64 dogs with a low-grade, completely resected stage I cMCT was performed: 35 (54.7%) dogs were subjected to OO and 29 (45.3%) underwent PRL. Dogs were monitored for a median of 813 and 763 days in the OO group and PRL group, respectively. The number of dogs undergoing MCT progression was significantly higher in the OO group (P = 0.028) and curve comparison revealed a tendency to a better time to progression in the PRL group (P = 0.058). No significant difference in survival time (P = 0.294) was observed between dogs in the OO and PRL groups. CONCLUSIONS: Our results showed that lack of immediate lymphadenectomy was associated with a higher risk for tumor progression. This preliminary judgement, reinforced by the findings that lymphadenectomy was well tolerated in all cases, and that histopathology provides the definitive assessment of the nodal pathological status, may suggest that prophylactic lymphadenectomy is indicated in the management of stage I MCTs. Larger prospective studies are warranted for generating clinical evidence of this latter hypothesis.

MAST CELL TUMORS IN CHEETAH (ACINONYX JUBATUS): A CASE SERIES.

Mast cell tumors in nondomestic felids are rarely reported and their biological characteristics are not well described. A retrospective review of the pathology records of 52 zoo-housed cheetahs (Acinonyx jubatus) identified five cases of mast cell tumor, involving four closely related individuals. The age at initial presentation varied from 14 mo to 6 yr. Four cases presented as solitary or multiple cutaneous masses that were mostly slow growing, up to 20 mm diameter, and predominantly nonulcerated. The diagnosis was made by fine needle aspiration cytology of a lesion in one case and by excisional biopsy in the others. Histopathologically, the lesions resembled low- to intermediate-grade canine mast cell tumors, with variations in the degree of anisocytosis and anisokaryosis. Surgical excision was incomplete for 80% of the cutaneous lesions, but local recurrence was not observed in any case. One animal with cutaneous lesions subsequently developed fatal visceral mastocytosis involving the spleen, liver, and adrenal gland. There was no evidence of lymph node invasion or paraneoplastic gastrointestinal signs in any of the cases.

Long-term outcomes of dogs undergoing surgical resection of mast cell tumors and soft tissue sarcomas: A prospective 2-year-long study.

OBJECTIVE: Report clinical outcomes of dogs with surgically excised mast cell tumors (MCT) and soft tissue sarcomas (STS). STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Fifty-three dogs with 52 MCT (50 low grade, 2 high grade) and 19 STS (12 grade I, 6 grade II, 1 grade III). METHODS: All dogs were examined at 3, 6, 12, 18, and 24 months postoperatively, with cytologic or histopathologic evaluation of suspected local recurrences. Dogs euthanized because of study tumor-related causes underwent necropsy. RESULTS: Median intraoperative margins were 20 mm and 30 mm wide for MCT and STS, respectively, with 1 fascial plane resected en bloc. The narrowest histologic tumor-free margins measured <1 mm in 21 of 52 (40%) MCT and 7 of 19 (37%) STS. All dogs were followed for 24 months. Two of 50 (4%) low-grade MCT were diagnosed, with local recurrence 181 and 265 days postoperatively. Two of 36 (6%) dogs with low-grade MCT developed visceral metastasis 181 and 730 days postoperatively. One of 2 dogs with high-grade MCT developed local recurrence 115 days postoperatively. No local recurrence or metastasis was diagnosed after excision of 19 STS. CONCLUSION: Local recurrence rates among predominantly low- to intermediate-grade MCT and STS were low, despite a high prevalence of histologic tumor-free margins <1 mm. Surgical recommendations for high-grade tumors cannot be extrapolated from this population. CLINICAL SIGNIFICANCE: Surgeons should seek to achieve microscopically complete excision for MCT and STS while minimizing patient morbidity and considering limitations of histopathology in predicting outcomes.

Prognostic Indicators and Clinical Outcome in Dogs with Subcutaneous Mast Cell Tumors Treated with Surgery Alone: 43 Cases.

The purpose of this study was to determine if clinical findings, histologic grade, or other histologic features were associated with clinical outcome in dogs with subcutaneous mast cell tumors (MCTs). Medical records of 43 client-owned dogs were retrospectively reviewed, and follow-up information was gathered via phone or follow-up examination. Progression-free survival (PFS), disease-free interval (DFI), and overall survival were calculated. Forty-two and twenty-two dogs, respectively, had grade 2 (Patnaik grading system) or low-grade tumors (two-tier grading system). Median PFS was 1474 days. Median DFI was not reached at >1968 days. Overall median survival time was not reached at >1968 days. In univariate analysis, argyrophilic nucleolar organizer regions (AgNORs), proliferating cell nuclear antigen, and mitotic index were negatively prognostic for PFS whereas Ki-67, proliferating cell nuclear antigen, and microvessel density were negatively prognostic for DFI. In multivariate analysis, AgNORs remained negatively prognostic for PFS. Results suggest that proliferation indices, especially AgNORs, may be useful in predicting the rare poor outcomes in dogs with subcutaneous MCTs. The vast majority of subcutaneous MCTs appear to be low or intermediate grade with excellent outcomes from good local tumor control.

Grading Cutaneous Mast Cell Tumors in Cats.

Cutaneous mast cell tumors (cMCTs) account for approximately 20% of skin neoplasms in cats. As there is no grading system for these tumors, prognosis is difficult to estimate. Although the typical presentation is a benign tumor that can be cured by surgical excision, a small but important proportion of feline cMCTs is biologically aggressive and can spread to local lymph nodes, precede the onset of disseminated cutaneous disease, or be associated with visceral involvement. A number of macroscopic and histologic features were retrospectively evaluated in cases of feline cMCTs treated with surgical excision with or without medical therapy. Cats were divided into 2 groups based on the clinical outcome. Group 1 included cats alive with no mast cell tumor-related disease at 1000 days from surgery; group 2 included cats developing histologically confirmed metastatic or cutaneous disseminated disease. The criteria allowing the best differentiation between the groups were used to develop a grading scheme. Groups 1 and 2 were composed by 48 (76%) and 15 (24%) cases, respectively. Tumors were classified as high grade if there were >5 mitotic figures in 10 fields (400×) and at least 2 of the following criteria: tumor diameter >1.5 cm, irregular nuclear shape, and nucleolar prominence/chromatin clusters. According to this scheme, the 15 (24%) high-grade cMCTs had significantly reduced survival time (median, 349 days; 95% CI, 0-739 days) as compared with the 48 low-grade tumors (median not reached; P < .001). Further studies are warranted to validate this grading system and test reproducibility on a larger case series.

Reductions in margin length after excision of grade II mast cell tumors and grade I and II soft tissue sarcomas in dogs.

OBJECTIVE: Quantify changes in the circumferential lengths of surgical margins of resected canine mast cell tumors (MCT) and soft tissue sarcomas (STS) between the time of collection and histopathology. STUDY DESIGN: Prospective, hypothesis-driven, clinical study. SAMPLE POPULATION: Two hundred and thirty-seven margins from 69 excised tumors (50 MCT and 19 STS) in 51 client-owned dogs. METHODS: The lengths of surgical margins were recorded (eg, cranial, caudal, dorsal, and ventral) for each tumor at 5 time points: intraoperatively (in vivo), immediately after excision (ex vivo), after formalin fixation (postfixation), once mounted on glass slides (subgross), and as histologically tumor-free margins (HTFMs). RESULTS: Compared to in vivo dimensions, the length of surgical margins at each processing step (ie, ex vivo, postfixation, subgross, and HTFM) was reduced by a median of 3.0, 5.0, 6.0, and 8.8 mm for MCT; 2.5, 2.0, 5.0, and 5.0 mm for STS. All processing steps resulted in significant reductions among MCT samples (P < .0001), except between postfixation vs subgross, and for STS samples (P < .0001), except between ex vivo vs postfixation and subgross vs HTFM. The maximum reduction in the total length of margins (from in vivo to HTFM) was 29.6 and 24.2 mm for MCT and STS, respectively. CONCLUSION: Surgical margin length reductions occur due to a combination of physical factors (eg, tissue elasticity, myofibril contraction, and histologic processing) and biological factors (eg, microscopic tumor infiltration into the grossly normal surgical margin). CLINICAL SIGNIFICANCE: These data provide information relevant to evidence-based surgical planning and may influence patient morbidity in the most commonly encountered cutaneous malignancies of dogs.

Shaved margin histopathology and imprint cytology for assessment of excision in canine mast cell tumors and soft tissue sarcomas.

OBJECTIVE: To determine the feasibility and agreement of margin assessment by imprint cytology, shaved margin histopathology, and radial section histopathology in canine cutaneous and subcutaneous mast cell tumors (MCT) and soft tissue sarcomas (STS). STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Three hundred and forty margins from 72 excised tumors (52 MCT and 20 STS) in 54 client-owned dogs. METHODS: Imprint cytology samples were acquired by pressing glass slides to the cut surgical margin of the freshly excised surgical specimen. Shaved margin samples were obtained from the patient wound bed using a scalpel immediately prior to closure. Radial section histopathology was performed as part of routine histopathologic processing. All margins were assessed as either positive or negative for presence of tumor cells at the surgical margin. Agreement among methods was calculated using Fleiss Kappa coefficients and an association of method, margin direction, and tumor type with positive margin status was evaluated using a general linear mixed model. RESULTS: Positive margin detection rates differed for MCT (imprint cytology 21%, radial section histopathology 9%, and shaved margin histopathology 3%; P < .0001) but not for STS. Intermethod agreement was poor (Fleiss Kappa = 0.051 and 0.176 for MCT and STS, respectively). Margin direction did not influence margin status for either tumor type. CONCLUSION: Imprint cytology and shaved margin histopathology are feasible, but their results are frequently disparate from routine radial section histopathology. Future studies are needed to evaluate the correlation of each method with local recurrence rates.

A Novel Imaging System Distinguishes Neoplastic from Normal Tissue During Resection of Soft Tissue Sarcomas and Mast Cell Tumors in Dogs.

OBJECTIVE: To assess the ability of a novel imaging system designed for intraoperative detection of residual cancer in tumor beds to distinguish neoplastic from normal tissue in dogs undergoing resection of soft tissue sarcoma (STS) and mast cell tumor (MCT). STUDY DESIGN: Non-randomized prospective clinical trial. ANIMALS: 12 dogs with STS and 7 dogs with MCT. METHODS: A fluorescent imaging agent that is activated by proteases in vivo was administered to the dogs 4-6 or 24-26 hours before tumor resection. During surgery, a handheld imaging device was used to measure fluorescence intensity within the cancerous portion of the resected specimen and determine an intensity threshold for subsequent identification of cancer. Selected areas within the resected specimen and tumor bed were then imaged, and biopsies (n=101) were obtained from areas that did or did not have a fluorescence intensity exceeding the threshold. Results of intraoperative fluorescence and histology were compared. RESULTS: The imaging system correctly distinguished cancer from normal tissue in 93/101 biopsies (92%). Using histology as the reference, the sensitivity and specificity of the imaging system for identification of cancer in biopsies were 92% and 92%, respectively. There were 10/19 (53%) dogs which exhibited transient facial erythema soon after injection of the imaging agent which responded to but was not consistently prevented by intravenous diphenhydramine. CONCLUSION: A fluorescence-based imaging system designed for intraoperative use can distinguish canine soft tissue sarcoma (STS) and mast cell tumor (MCT) tissue from normal tissue with a high degree of accuracy. The system has potential to assist surgeons in assessing the adequacy of tumor resections during surgery, potentially reducing the risk of local tumor recurrence. Although responsive to antihistamines, the risk of hypersensitivity needs to be considered in light of the potential benefits of this imaging system in dogs.

Mast cell tumor invading the cornea in a horse.

A 3-year-old Marwari mare was presented for evaluation of an irregular, reddish mass protruding from behind the right third eyelid. The mass appeared to arise at the ventral limbal area, involved the perilimbal bulbar conjunctiva and widely extended into corneal tissue. No other ocular or systemic abnormalities were detected at the time of presentation. The mass was surgically removed by lamellar keratectomy, with defocused CO(2) laser used as adjunctive therapy to treat the surgical exposed area and its surroundings. Histopathologic evaluation showed sheets of densely packed, well-differentiated neoplastic mast cells separated by fibrovascular connective tissue. Nuclear staining for Ki-67 was performed, and an average of 370 cells were positive per 1000 counted cells. Two months postoperatively, the surgical site was filled with flat fibrovascular and pigmented tissue, while the surrounding cornea was transparent with no superficial vascularization around the fibrotic scar. Thirty-two months after treatment, no recurrence of the neoplasia was reported.

Additional local therapy with primary re-excision or radiation therapy improves survival and local control after incomplete or close surgical excision of mast cell tumors in dogs.

OBJECTIVE: To compare survival and local recurrence outcomes in dogs with mast cell tumors with incomplete or close margins treated with primary re-excision or radiation therapy of the primary site versus no additional local therapy. STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n = 64). METHODS: Outcomes of canine mast cell tumor cases that had incomplete or close surgical resection and presented to the Ontario Veterinary College Health Sciences Centre (2001-2010) were evaluated after additional local therapy (primary re-excision or radiation therapy) or no additional local therapy (comparison). Follow-up was performed through evaluation of medical records and telephone contact with referring veterinarians and owners. RESULTS: Tumors (n = 70) in 64 dogs were studied. Median survival times for the primary re-excision (2930 days) and radiation therapy (2194 days) groups were significantly longer than for the comparison (710 days) group. Local recurrence occurred in 13% of the re-excision group, 8% of the radiation therapy group, and 38% of the comparison group. Although local recurrence rate was not statistically significant for the re-excision group, time to local recurrence was statistically longer for both the re-excision and radiation groups. Adjunctive chemotherapy was not associated with improved survival or local control. CONCLUSION/CLINICAL RELEVANCE: There is significant improvement in survival and duration of local control when additional local therapy is performed after incomplete or close resection of mast cell tumors. These follow-up therapies should be recommended to owners when mast cell tumors are incompletely or closely resected.

Moh's micrographic surgery for the management of a periocular mast cell tumor in a dog.

A 3-year-old neutered male boxer dog presented with a 6-month history of a waxing and waning mass of the left dorsotemporal eyelid margin. Cytology and biopsy confirmed a diagnosis of mast cell neoplasia. Systemic staging of the dog failed to reveal any evidence of metastatic neoplasia. Owing to the location of the tumor within the eyelid margin and the wide surgical margins recommended for excision of mast cell tumors, Mohs micrographic surgery (MMS) was chosen for its potential to conserve tissues while providing intraoperative confirmation the tumor was completely excised. Utilizing MMS horizontal sectioning technique, 100% of the surgical margins were assessed prior to closure of the surgical wound. This represents the first time a comprehensive MMS protocol was used in a veterinary patient under general anesthesia.

Pilot study of the suitability of dorsal vulval skin as a transposition flap: vascular anatomic study and clinical application.

OBJECTIVE: To identify the blood supply to the vulval fold and adjacent skin, and evaluate it as a transposition flap for closing perineal wounds in dogs. STUDY DESIGN: Prospective study. ANIMALS OR SAMPLE POPULATION: Five female canine cadavers and 2 cases referred for excision of mast cell tumors adjacent to the vulva. METHODS: Dissection was performed to identify the vascular supply to the vulval fold in two cadavers following arterial injection of red latex and methylene blue, respectively. In three cadavers, barium sulfate mixed 1:1 with water was injected into the terminal aorta. The vulval fold and surrounding perineal skin was excised and radiographed. Transposition flaps using the vulval fold and adjacent skin were used to close skin defects in two dogs presented for wide excision of mast cell tumors situated ventro-lateral and dorso-lateral to the vulva, respectively. RESULTS: The vulval fold and adjacent skin was perfused bilaterally by branches of the ventral perineal and external pudendal arteries, which entered dorsally and ventrally, respectively. As incisions used to create a transposition flaps from the skin surrounding the vulval fold transect these vessels, the flap is dependent on the sub-dermal plexus for survival. There was 100% survival of transposition flaps in the 2 clinical cases and healing proceeded uneventfully with acceptable cosmetic and functional results. CONCLUSIONS: The vulval fold and surrounding skin can be used as a subdermal plexus flap to close large perineal defects in dogs. CLINICAL RELEVANCE: Availability of a defined local skin flap will improve treatment of diseases resulting in large perineal skin defects in female dogs.

Nasal-skin-fold transposition flap for upper lip reconstruction in a French bulldog.

Upper-lip reconstruction after mast-cell tumor-resection in a French bulldog was achieved by using a transposition flap from the nasal-skin-fold and an oral mucosal flap. The new technique is an alternative for reconstruction of extensive upper-lip defects in brachycephalic dogs and achieves satisfactory functional and cosmetic results.

Lambeau de transposition provenant du repli cutané nasal pour une reconstruction de la lèvre supérieure chez un Bouledogue français. Une reconstruction de la lèvre supérieure après une résection d'une tumeur à mastocytes chez un Bouledogue français a été réalisée en utilisant un lambeau de transposition provenant du repli cutané nasal et un lambeau oral des muqueuses. La nouvelle technique représente une option pour la reconstruction de défauts importants de la lèvre supérieure chez les chiens brachycéphaliques et donne des résultats fonctionnels et esthétiques satisfaisants.(Traduit par Isabelle Vallières).

Canine subcutaneous mast cell tumor: characterization and prognostic indices.

Histologic grading schemes for canine cutaneous mast cell tumors (MCTs) were not developed for subcutaneous MCTs. Despite this, subcutaneous MCTs are currently categorized by many as grade II or higher. The aim of this investigation was to assess the pathology and clinical outcome for subcutaneous MCTs to provide a more accurate prognosis. Information on clinical outcome for 306 dogs was obtained from veterinarians and correlated with histologic features. Mean and median follow-up was 842 and 891 days, respectively (range, 3-2,305 days). Only 27 (9%) were confirmed as mast cell-related deaths. Metastasis occurred in 13 (4%), and 24 (8%) had local reoccurrence, even though 171 (56%) cases had incomplete surgical margins. Median survival time was not reached, and the estimated 6-month, 1-, 2-, and 5-year survival probabilities were 95%, 93%, 92%, and 86%, respectively. Dogs were euthanized or died as a result of local tumor reoccurrence, additional MCT development distant to the surgical site, or metastasis. Decreased survival time was linked to mitotic index (number of mitotic figures per 10 high-power fields), infiltrative growth pattern, and presence of multinucleation. Both univariable and multivariable analysis showed mitotic index to be strongly predictive of survival, local reoccurrence, and metastasis. The results of the study indicate that the majority of subcutaneous MCTs have a favorable prognosis, with extended survival times and low rates of reoccurrence and metastasis.

Canine conjunctival mast cell tumors: a retrospective study.

OBJECTIVE: To describe signalment, clinical presentation, treatment, recurrence rate, and outcome of canine conjunctival mast cell tumors (MCTs). DESIGN: Retrospective study. PROCEDURES: Canine cases were selected from the Comparative Ocular Pathology Laboratory of Wisconsin, Eye Path Lab of the UK, and California Eye Care for Animals. Thirty-two canine patients were identified as having a MCT presumed to be arising primarily from the conjunctiva. Data were collected from pathology submission request forms; additional information was collected by means of a questionnaire distributed to the veterinary ophthalmologist or veterinarian who performed the surgery. Data collected included age, gender, breed, location of tumor, dimensions of tumor, duration and growth rate, additional diagnostics, surgical descriptions, adjunctive treatment, histologic description, special stains, number of recurrences, and final outcome. RESULTS: Thirty-two dogs with 33 conjunctival MCTs meeting search criteria were identified. All dogs underwent surgical excision as the primary treatment. Surgical margins were evaluated for 30 tumors and were reported as: incomplete margins in 25 cases, narrow in four cases and complete in one case. Histologic grade was provided for 33 of 33 MCTs and included 10 low (30%), 18 intermediate (55%) and five high-grade (15%) tumors. Follow up information was received for 25 dogs. Four died of unrelated causes, two had local recurrence, 15 were currently disease free (mean 21.4 months postoperatively) and four were reported to be disease free at the reported rechecks but were lost to long term follow up (mean 13 months postoperatively). No dogs in the study were identified that died of MCT related disease.

Use of an axial pattern skin flap based on the cranial cutaneous branch of the saphenous artery in the dog.

OBJECTIVE: To report the use of an axial pattern flap based on the cranial cutaneous branch of the saphenous artery to close a skin defect left on the medial crus after mast cell tumour removal. CASE REPORT: A seven-year-old, 32.41 kg, neutered male mixed-breed dog had a mast cell tumour incompletely excised from the left medial crus. The resulting 6 cm linear scar was excised with 2 cm wide margins and one fascial plane for deep margins. An axial pattern skin flap incorporating the cranial cutaneous branch of the saphenous artery was used to close the resultant skin defect. RESULTS: The histopathology report documented clean margins and the flap survived completely. A seroma developed postoperatively, however it resolved without treatment. CLINICAL SIGNIFICANCE: An axial pattern skin flap based on the cranial cutaneous branch of the saphenous artery is a viable option for closing medial crus skin defects in the dog.

The feasibility and utility of optical coherence tomography directed histopathology for surgical margin assessment of canine mast cell tumours.

Histopathologic surgical margin assessment in veterinary patients is an imprecise science with assessment limited to a small proportion of the surgical margin due to time and finances. Incomplete excision of canine mast cell tumours (MCTs) alters treatment recommendations and prognosis. Optical coherence tomography (OCT) is a novel imaging modality that has been reported in a single veterinary study for surgical margin assessment. Twenty-five dogs with 34 MCTs were enrolled in a prospective pilot-study to assess the imaging characteristics of canine MCTs with OCT and to evaluate the feasibility and utility of OCT-guided histopathology. All dogs underwent routine surgical excision of MCTs. OCT imaging was used to assess the entire surgical margin prior to placement in formalin. Either normal areas or areas suspected of incomplete MCT excision were inked. Standard histopathologic sectioning and tangential sectioning of inked areas were performed and compared to OCT results. OCT identified MCT near the surgical margin in 10 of 26 specimens (38.4%). Four specimens suspicious for incomplete margins on OCT had incomplete MCT excision that was missed on standard histopathologic sectioning. Six specimens had OCT-guided sections taken as suspicious, which did not show MCT on histopathology. OCT-guided pathology sections were able to detect incompletely excised MCT near the surgical margin with a sensitivity of 90% and specificity of 56.2% in this preliminary study. OCT imaging shows promise for guiding pathologists to areas of interest to improve the diagnostic accuracy of surgical margin assessment in excised canine MCTs.

Mast cell tumors in a llama (Lama glama).

A 9-year-old female llama (Lama glama) that served as a blood donor at The Ohio State University Veterinary Teaching Hospital developed multiple small, raised, firm, non-haired cutaneous masses on the right hip, left cheek, and right and left shoulders. Cytological evaluation of fine-needle aspirates from the cutaneous mass from the left shoulder and right hip comprised many well-differentiated, highly granulated mast cells with moderate numbers of eosinophils. Occasional mast cells exhibited erythrophagocytosis and contained a small amount of hemosiderin or several variably sized vacuoles. A cytologic diagnosis of mast cell tumor with evidence of prior hemorrhage was made, and the masses were surgically removed. Microscopically, each mass consisted of sheets of neoplastic round cells that formed nonencapsulated nodules in the dermis and infiltrated into the adjacent dermal collagen. Eosinophils were scattered among the mast cells at the periphery of the nodules. Neoplastic mast cells, but not eosinophils, exhibited positive membrane KIT expression and cytoplasmic vimentin staining. A final diagnosis of mast cell tumor was made based on cytology, histology, and immunohistochemistry.

Prognostic significance of surgical margin, Ki-67 and cyclin D1 protein expression in grade II canine cutaneous mast cell tumor.

The prognosis for canine cutaneous mast cell tumor (CCMT) is thought to be correlated with histopathological grading. However, the wide variety of histopathologic types of grade II is one of the most troublesome and difficult points for prognosis. The objective of this study is to determine the prognostic value of surgical margin, ki-67 and cyclin D1 protein expression in grade II tumor. Surgically resected specimens of solitary grade II CCMT from 48 dogs with follow-up periods over 360 days (median was 1080 days) were used in this study. The expression of cyclin D1 and ki-67 proteins was determined by morphometrically using slides stained immunocytochemically, and the correlations among the results, survival rate, and recurrence and/or metastasis rate of each dog were analyzed statistically. The recurrence and/or metastasis and mortality rate in the incomplete surgical excision group within 30 months postoperatively were higher than that of the complete surgical excision group. In the incomplete surgical excision group, dogs with low positive staining of ki-67 had a significantly better survival, but the recurrence and metastasis rate and ki-67 positivity failed to show a significant correlation. Only a small number of cases showed cyclin D1-positive tumor cells, but most of them had a poor outcome with a high recurrence rate. In grade II CCMT, incomplete excision induced a relatively high metastasis rate and poor prognosis. Ki-67 positivity is a marker for the estimation of overall survival in incomplete surgical excision cases. Cyclin D1 positivity was low and may not have a prognostic role.

Adjuvant electrochemotherapy for the treatment of incompletely resected canine mast cell tumors.

BACKGROUND: Electrochemotherapy (ECT) is a novel anticancer therapy that combines the delivery of trains of appropriate waveforms with the local administration of chemotherapy agents. The purpose of this investigation was to assess the adjuvant potentials of ECT for the treatment of incompletely excised mast cell tumors (MCT). MATERIALS AND METHODS: Twenty-eight privately-owned dogs with incompletely removed MCT were treated with intralesional bleomycin (1.5 IU/cm2) followed by the application of trains of biphasic pulses (8 pulses, 1300 V/cm, 50 + 50 micros duration, 1 Hz frequency). RESULTS: The overall response rate was 85% with a mean estimated time to recurrence of 52.76 +/- 6.5 months (range: 39.99 to 65.54 months, 95% CI). At the time of writing this report, the median survival time was not reached. Three dogs died of metastatic disease that they developed at the same time of local recurrence, one developed multiple cutaneous nodules at different locations and one with recurrence was re-treated and is currently disease-free after 22 months. No major local or systemic toxicities were noted for the duration of the study. CONCLUSION: ECT is a safe and effective therapy for incompletely excised MCTs in companion animals. Its ease of administration, lack of toxicities and low cost make it an attractive alternative to standard treatments and warrants further investigation.