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Background: Traditionally, wide lateral surgical margins of 3 cm and one fascial plane deep have been recommended for resection of canine cutaneous mast cell tumor (MCT). Several studies have been published assessing surgical margins of less than this traditional recommendation. The objective of this systematic review was to determine if resection MCT with lateral surgical margins < 3 cm results in low rates of incomplete resection and local tumor recurrence. Systematic searches of digital bibliographic databases were performed with two authors (AR & LES) screening abstracts to identify relevant scientific articles. Studies regarding surgical treatment of dogs with cutaneous MCT were reviewed. Data abstraction was performed and the quality of individual studies and the strength of the body of evidence for utilization of surgical margins < 3 cm for removal of MCTs was assessed., Results: From the initial 78 citations identified through the database searches, four articles were retained for data abstraction after both relevance screenings were performed. Two studies were retrospective observational studies, one was a prospective case series and one was a prospective clinical trial. Assessment of the quality level of the body of evidence identified using the GRADE system was low. Excision of MCT at 2 cm and 3 cm was associated with comparably low rates of incomplete excision and recurrence., Conclusions: Despite the low quality of the overall body of evidence, a recommendation can be made that resection of canine cutaneous MCTs (< 4 cm) of Patnaik grade I and II with 2 cm lateral margins and 1 fascial plane deep results in low rates of incomplete excision and local tumor recurrence.

In this report, we present a 53-year-old woman with primary mast cell sarcoma of the thoracic spine vertebrae. Mast cell sarcoma is an aggressive and rare cancer. To date, no cases of primary mast cell sarcoma have been reported in the spinal vertebrae. The patient initially presented with a 1-month history of pelvic and abdominal pain. Inconclusive gynecological evaluation resulted in a CT of the abdomen and pelvis, demonstrating a destructive lesion centered at the 11 th thoracic vertebral body. The patient underwent a two-stage spine operation for T11 corpectomy and T7-L3 posterior spinal fusion. Histopathological, immunohistochemical, and flow cytometry studies of the resection specimens showed the tumor to be mostly composed of CD117-positive and mast cell tryptase-positive cells with features consistent with mast cell sarcoma. This is the first reported case of primary vertebral mast cell sarcoma, which may mimic other destructive lesions of the spine including osteomyelitis, vertebral tuberculosis, or plasmacytoma.
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OBJECTIVE To evaluate the effects of IV diphenhydramine hydrochloride administration on cardiorespiratory variables in anesthetized dogs undergoing mast cell tumor (MCT) excision. DESIGN Randomized, blinded clinical trial. ANIMALS 16 client-owned dogs with MCTs. PROCEDURES In a standardized isoflurane anesthesia session that included mechanical ventilation, dogs received diphenhydramine hydrochloride (1 mg/kg [0.45 mg/lb], IV; n = 8) or an equivalent volume of saline (0.9% NaCl) solution (IV; control treatment; 8) 10 minutes after induction. Cardiorespiratory variables were recorded throughout anesthesia and MCT excision, and blood samples for determination of plasma diphenhydramine and histamine concentrations were collected prior to premedication (baseline), throughout anesthesia, and 2 hours after extubation. RESULTS Cardiorespiratory values in both treatment groups were acceptable for anesthetized dogs. Mean ± SD diastolic arterial blood pressure was significantly lower in the diphenhydramine versus control group during tumor dissection (52 ± 10 mm Hg vs 62 ± 9 mm Hg) and surgical closure (51 ± 10 mm Hg vs 65 ± 9 mm Hg). Mean arterial blood pressure was significantly lower in the diphenhydramine versus control group during surgical closure (65 ± 12 mm Hg vs 78 ± 11 mm Hg), despite a higher cardiac index value. Plasma histamine concentrations were nonsignificantly higher than baseline during maximal manipulation of the tumor and surgical preparation in the diphenhydramine group and during surgical dissection in the control group. CONCLUSIONS AND CLINICAL RELEVANCE IV administration of diphenhydramine prior to MCT excision had no clear clinical cardiorespiratory benefits over placebo in isoflurane-anesthetized dogs.

Canine mast cell tumors (MCTs) are the most common cutaneous neoplasm in the dog. It has been suggested that MCT in certain locations may behave in a more biologically aggressive fashion than MCTs located in others; however, no published data are available for MCTs of canine pinnae treated with surgical excision. A retrospective study of 28 animals with surgical excision of MCTs of pinnae was completed with a medical record review and follow-up questionnaire to the operating veterinarian. The effect of tumor grade, clean or dirty excision, cartilage penetration, and mitotic index (MI) on local recurrence and survival time (ST) was evaluated. There was local recurrence in one dog with a grade 2 MCT and in seven of eight dogs with grade 3 MCTs. The median ST of animals with grade 1 and 2 MCTs was not reached, whereas the median ST of animals with grade 3 MCTs was 10 mo. There was no statistical association between histologically clean and dirty margins and either local recurrence or ST. A prolonged disease free interval without local recurrence may be achieved with local excision of grade 1 and 2 MCTs. Animals with grade 3 MCTs had a uniformly poor outcome with short times to local recurrence and death.

Mast cell sarcoma is a disorder that results in abnormal mast cells as identified by morphology, special stains, and in some publications, c-kit mutation analysis. It affects animal species such as canines more commonly than humans. In humans it is a very rare condition, with variable clinical presentation. There is no standard therapy for the disorder. It can affect any age group. It is occasionally associated with systemic mastocytosis and/or urticaria pigmentosa. The prognosis of mast cell sarcoma in published literature is very poor in humans., (Copyright © 2014 Elsevier Inc. All rights reserved.)

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.

Mastocytosis is a neoplastic disease of mast cells and their CD34+ precursors, including a heterogeneous group of disorders. It is characterized by abnormal growth and accumulation of mast cells in one or more organ systems. Mast cell sarcoma is an extremely rare and aggressive disease characterized by local proliferation of atypical mast cells, destructive growth and poor prognosis, without systemic involvement. Very few clinical cases describing this entity have been reported in the literature. In this paper, we report a case of a mast cell sarcoma, localized in the scalp of a 63-year-old woman; it appears to be the first manifestation of undisclosed systemic mastocytosis., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

Objective: To assess the usefulness of histologic evaluation of surgical margins to predict local recurrence of cutaneous malignant tumors in dogs and cats treated by means of surgical excision., Design: Prospective case series., Animals: 40 dogs and 20 cats., Procedures: 60 surgically excised tumors (20 soft tissue sarcomas [STSs], 20 mast cell tumors [MCTs], and 20 carcinomas) were examined histologically. Margins were classified as clean, close, or infiltrated; histologic grade was assessed in STSs and MCTs. Recurrence rates and recurrence-free intervals (RFIs) during a 24-month follow-up period were recorded, and method accuracy was calculated., Results: Surgical margins were clean in 29 of 60 (48%) tumors, close in 11 (18%), and infiltrated in 20 (33%). Tumors recurred in 27 of 60 (45%) animals, with a mean ± SD RFI of 229 ± 173 days. Recurrence rates for animals that had tumors with infiltrated (16/20) or close (8/11) margins were significantly higher than recurrence rate for animals that had tumors with clean margins (3/29). Margin classification was a significant predictor of RFI. Accuracy of the method to predict recurrence was 94% for carcinomas, 87% for STSs, and 76% for MCTs., Conclusions and Clinical Relevance: Histologic assessment of margin status was useful for predicting local recurrence of cutaneous malignant tumors in dogs and cats treated by means of excision alone. Method accuracy varied among tumor types and grades. Recurrence times suggested postsurgical follow-up should continue for ≥ 2 years. Results were similar for animals with infiltrated and close tumor margins, and careful postsurgical management is recommended for both.

The recommended treatment for soft tissue sarcomas (STS) and mast cell tumors (MCT) is complete surgical removal, provided that the tumor is amenable to surgical excision. The objective of this study was to evaluate possible risk factors for incomplete surgical excision of skin and subcutaneous STS and MCT in 100 dogs treated with wide excision with curative intent. Decreased body weight was a risk factor (P = 0.03, odd's ratio = 0.96) as well as increased tumor size (1.4% increase in risk of incomplete excision per cm(2); P = 0.02). Gender, age, breed, location, grade, tumor type, re-excision, and level of surgeon's training (P = 0.0711) were not significant. Veterinary surgery residents were at increased risk of incompleteness of excision compared with ACVS surgeons and ACVS surgeons with additional training in surgical oncology.

Objective: To evaluate the relationship between width and depth of surgical margins, amount of edema within and around the tumor, and degree of demarcation between the tumor and surrounding tissues with the clinical outcome following surgical removal of cutaneous mast cell tumors (cMCTs) in dogs., Design: Retrospective cohort study., Animals: 100 dogs with 115 resectable cMCTs., Procedures: Information about the dogs' clinical outcomes following cMCT removal was obtained from primary care veterinarians. Histologic sections of excised tumors were assessed retrospectively for tumor grade and measurement of the narrowest lateral and deep margins of nonneoplastic tissue excised with the tumors; edema within the tumor and surrounding tissues was assessed as minimal, moderate, or severe. Tumors were classified as poorly, moderately, or well demarcated on the basis of the degree of mast cell infiltration into the adjoining connective tissue., Results: Following tumor excision (with no additional postsurgery treatment), 96 dogs had no local recurrence or metastatic disease for 27 to 31 months; 4 metastatic disease-related deaths (dogs with grade II or III tumors) occurred within 3 to 9 months. Histologically, mean lateral and deep surgical margins around the tumors were 8.9 and 5.3 mm, respectively. No recurrence of tumor or metastatic disease developed following excision with lateral margins ≥ 10 mm and deep margins ≥ 4 mm. Edema and degree of demarcation were not correlated with outcome., Conclusions and Clinical Relevance: Results suggested that most grade I and II cMCTs in dogs can be successfully treated by complete surgical removal with margins smaller than those currently recommended.

A 10-year-old Boston terrier dog was presented for treatment of a 2-cm mast cell tumor of the left upper lip and nasal planum immediately adjacent to the philtrum and ventral to the nares. CO2 laser was used for resection of the lesion. Wound reconstruction was performed using bilateral labial advancement flaps.

The use of adjuvant 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU; lomustine) to treat incompletely excised canine mast cell tumors (MCTs) has not been evaluated. Medical records of 12 dogs with grade 2 MCT treated with incomplete surgical excision and adjuvant CCNU and prednisone chemotherapy were reviewed. Local recurrence rate, metastasis rate, and survival time were evaluated. None of the dogs developed local recurrence or regional/ distant metastases. Two dogs developed fatal liver failure. The 1- and 2-year progression-free rates of surviving dogs were 100% and 77%, respectively. Postoperative adjuvant CCNU appears to be a useful alternative to radiation therapy for incompletely excised canine cutaneous MCTs.

A 10-year-old male neutered Boxer presented with recurrence of a mast cell tumor at the right medial canthal area. Following excision including 2 cm margins, the medial one-half of the upper and lower eyelids and the medial canthus were reconstructed using an axial pattern flap based on the cutaneous branch of the superficial temporal artery. The bulbar conjunctiva of the nictitans was preserved and sutured to the medial flap edge, thus creating a conjunctival lining to the deep aspect of the flap, protecting corneal epithelium. This is a valuable surgical technique for closing a large skin defect and reconstructing the medial eyelids, thus preserving the globe.

Objective: To evaluate efficacy of hypotonic water as adjuvant therapy after marginal resection of canine mast cell tumors (MCT)., Study Design: Double-blinded, placebo-controlled, prospective, randomized study., Animals: Dogs (n=30) with spontaneous, cutaneous, solitary MCT., Methods: The wound bed of MCT, resected with margins <0.5 cm, was injected with either hypotonic or isotonic water according to a standardized protocol. Follow-up was obtained by clinical examination at 1, 2, 3, 6, and 12 months and annual telephone contact with the owner., Results: Eighteen dogs were treated with isotonic lactated Ringer's solution and 12 dogs with hypotonic distilled water. All MCT were stage 0 tumors and most grade II. Six tumors (4 isotonic, 2 hypotonic) recurred locally, 3 of these dogs died from disease-related reasons within 4 months. The surviving 3 dogs were alive with a median survival time (ST) of 1092 days. The calculated 2-year recurrence-free rate was 92.7%; the 2-year disease-free rate 79.1%; and the 2-year survival rate 89.5%. No significant differences in local recurrence and ST were observed between treatment groups. Histologic grading was the only significant prognosticator for ST and recurrence-free periods., Conclusion: No significant differences in local recurrence and ST were observed between adjunctive hypotonic water and placebo treatment after marginal resection of solitary MCT., Clinical Relevance: Hypotonic water does not decrease the rate of local recurrence in dogs with solitary MCT after marginal surgical excision.

Objective: To determine response rate and reduction in tumor burden and effect of dose on tumor response in dogs treated with neoadjuvant prednisone for cutaneous mast cell tumors (MCTs)., Design: Combined prospective clinical study and retrospective case series., Animals: 49 dogs with MCT., Procedures: Medical records were retrospectively reviewed for dogs with primary untreated cutaneous MCT managed with neoadjuvant prednisone administration and surgery. Tumor characteristics and response to treatment were recorded. A subset of dogs assigned to low-dose (LD) treatment with neoadjuvant prednisone (1.0 mg/kg [0.45 mg/lb], PO, q 24 h) or high-dose (HD) treatment (2.2 mg/kg [1.0 mg/lb], PO, q 24 h) was used to determine the effects of dose., Results: The overall objective response rate was 70% for dogs treated with neoadjuvant prednisone; prednisone dose was not significantly associated with response. Prospectively, the median sum maximal diameter (MaxD) reduction was 45.2%, and reduction in tumor volume was 80.6%. In both treatment groups, the mean percentage MaxD reduction and tumor volume reduction were significant. The difference in response between the LD and HD groups was not significant. The LD group had mean MaxD and tumor volume reductions of 35.4% and 52.5%, respectively, compared with mean reductions of 48.8% in MaxD and 78% in tumor volume in the HD group., Conclusions and Clinical Relevance: Treatment with neoadjuvant prednisone appears to be useful for inducing reduction of MCTs and may facilitate resection when adequate surgical margins cannot be confidently attained because of mass location or size or both.

Objective: To evaluate completeness of excision and clinical outcome in dogs with cutaneous mast cell tumors (MCTs) excised with a lateral margin of 2 cm and a deep margin of 1 fascial plane., Design: Prospective study., Animals: 16 client-owned dogs with 1 or more cutaneous MCTs., Procedure: Excision of MCTs was performed with a 2-cm lateral margin and a deep margin of 1 fascial plane. Histologic tumor grading was performed; surgical margins were categorized as complete or incomplete. Follow-up information was obtained via repeat examination of the dogs by veterinarians or client-completed questionnaires., Results: 4 grade I and 19 grade II cutaneous MCTs were evaluated. Overall, 21 (91%) MCTs were completely excised; 2 grade II tumors had foci of mast cells at the 2-cm margin. Two dogs received adjunctive treatments following surgery. Follow-up information was available for all dogs (median follow-up period, 379 days; range, 51 to 538 days); no local recurrence was detected during this time. De novo MCTs were detected in 3 of 16 dogs at 37, 54, and 154 days after surgery. Via Kaplan-Meier analysis, median survival time and disease-free interval were both > 538 days (medians not yet reached). No prognostic variables were identified., Conclusions and Clinical Relevance: Excision with a 2-cm lateral margin and a deep margin of 1 fascial plane may result in satisfactory excision of grades I and II MCTs in dogs, with recurrence rates similar to those reported previously. Use of these margins may minimize complications associated with larger local tumor resection.

Objective: To evaluate prognostic factors associated with outcome of dogs with multiple cutaneous mast cell tumors (MCTs) treated with surgery with or without adjuvant treatment., Design: Retrospective case series., Animals: 54 dogs with a minimum of 2 simultaneous, histologically confirmed cutaneous MCTs that had been excised and had adequate staging and follow-up data., Procedure: Medical records from 1998 to 2004 were examined. Outcome was assessed with the Kaplan-Meier product-limit method and log-rank analysis. Prognostic factors evaluated included signalment; number, histologic grade, location, size, local recurrence, and de novo development of MCTs; quality of surgical margins; clinical signs at the time of diagnosis; and use of adjuvant treatment., Results: Medical records of 54 dogs with 153 tumors were included. Median follow-up time was 658 days. Median disease-free interval (1,917 days; range, 11 to 1,917 days) and median survival time (1,917 days; range, 14 to 1,917 days) were not yet reached. The 1- year and 2- to 5-year survival rates were 87% and 85%, respectively. The overall rate of metastasis was 15%. Factors that negatively influenced survival time in the univariate analysis included incomplete excision, local recurrence, size > 3 cm, clinical signs at the time of diagnosis, and use of adjuvant treatment. Presence of clinical signs at the time of diagnosis was the only negative prognostic factor for disease-free interval detected in the multivariate analysis., Conclusions and Clinical Relevance: Results suggested that multiple cutaneous MCTs in dogs are associated with a low rate of metastasis and a good prognosis for long-term survival with adequate excision of all MCTs.

The goal of this study was to determine the significance of tumour depth, tumour location and multiple synchronous tumour masses for the prognostic evaluation of canine cutaneous mast cell tumours (MCTs). The study population consisted of 100 formalin-fixed, paraffin-embedded cutaneous MCTs that had been surgically removed from 100 dogs and submitted to the Diagnostic Center of Population and Animal Health at Michigan State University between 1998 and 2001. None of the dogs had received chemotherapy or radiation therapy. For each case the following data were obtained from the referring veterinarians: sex, breed, weight, age at diagnosis, diagnostics performed, adjunct medications given at the time of surgery, tumour location, number of tumour masses, tumour recurrence (development of MCTs at the surgical site), development of additional MCTs at distant sites (outside the surgical margins), tumour duration before removal, survival time and cause of death, if applicable. Tumour depth was determined through microscopic evaluation of 5 microm sections stained with haematoxylin and eosin. Based on univariable and multivariable survival analysis, dogs with multiple synchronous cutaneous MCTs at the time of diagnosis have a worse prognosis compared with dogs with single tumours. Additional treatment beyond surgical excision alone should be considered for these animals. Older dogs and Boxers with cutaneous MCTs were at higher risk to develop additional MCTs at distant sites (outside the surgical margins), and older and male dogs with cutaneous MCTs had significantly shorter survival times. Univariable analysis also determined that dogs with cutaneous MCTs located on the head and neck had an increased risk of additional MCT development at distant sites and that sterilized dogs with cutaneous MCTs had shorter survival times. However, these findings were not confirmed by multivariable analysis. Tumour depth was of no prognostic significance for dogs with cutaneous MCTs.

Objective: To compare clinical outcome of dogs with cutaneous mast cell tumors (MCTs) in the inguinal or perineal region with outcome for dogs with MCTs in other cutaneous locations., Design: Retrospective study., Animals: 37 dogs with MCTs in the inguinal or perineal region and 87 dogs with MCTs in other cutaneous locations., Procedure: Information obtained from the medical records included sex, breed, age, histologic grade of all tumors, number and location of all tumors, tumor size (ie, diameter of the tumor), completeness of surgical excision, treatments administered in addition to surgery, and outcome. In all dogs, the primary treatment consisted of surgical excision., Results: Disease-free interval and survival time for dogs with MCTs in the inguinal or perineal region were not significantly different from values for dogs with MCTs in other cutaneous locations. Dogs with incompletely excised tumors, dogs with grade III tumors, and dogs that received systemic treatment were 2, 2.5, and 4 times as likely, respectively, to have a relapse. Factors significantly associated with a shorter survival time were age > 8 years, metastatic disease at the time of initial diagnosis, and tumor relapse., Conclusions and Clinical Relevance: Results of the present study suggest that dogs with MCTs in the inguinal or perineal region do not have a worse prognosis in regard to disease-free interval or survival time than do dogs with MCTs in other cutaneous locations. Treatment recommendations for dogs with cutaneous MCTs should be based on confirmed predictors of biological behavior, such as histologic grade and clinical stage.

Objective: To determine the prognostic factors for survival and tumor recurrence in dogs with cutaneous mast cell tumors (MCTs) in the perineal and inguinal regions treated surgically with or without adjunctive radiation therapy, chemotherapy, or both., Design: Retrospective study., Animals: 68 dogs., Procedure: Medical records of dogs with histologically confirmed MCTs in the perineal region, inguinal region, or both treated surgically with or without adjunctive radiation therapy, chemotherapy, or both were reviewed., Results: Mean tumor-free interval was 1,635 days (median not reached), and 1- and 2-year tumor-free rates were 79% and 71%, respectively. Median survival time was 1,111 days (mean, 1,223 days), and 1- and 2-year survival rates were 79% and 61%, respectively. Factors that negatively influenced survival time were age at diagnosis, tumor recurrence, and treatment with lomustine., Conclusions and Clinical Relevance: Results indicated that dogs with MCTs in the inguinal and perineal regions, if appropriately treated, may have survival times and tumor-free intervals similar to dogs with MCTs in other locations.

The histological grade of 340 cutaneous mast cell tumours derived from 280 dogs was determined by an established histological grading system; 87 of the tumours (26 per cent) were well differentiated, 199 (59 per cent) were intermediately differentiated and 54 (16 per cent) were poorly differentiated. The one-year survival rates for the dogs with tumours of these three grades were significantly different (P = 0.0001), being 100 per cent, 92 per cent and 46 per cent, respectively. The median survival time for the dogs with poorly differentiated tumours was 278 days, significantly shorter than that for the dogs with either intermediately or well-differentiated tumours, which were both over 1300 days. Regrowth of the tumours was identified in 10 (19 per cent) of the dogs with poorly differentiated tumours, 12 (6 per cent) of the dogs with intermediately differentiated tumours and one of the dogs with well-differentiated tumours; only three of the tumours which regrew had initially had complete margins. The results suggest that wide surgical margins are not a prerequisite for a successful long-term outcome in dogs with well-differentiated cutaneous mast cell tumours.

Objective: To describe use of the scrotum as a pedicle flap to cover defects created by tumor excision in the perineum or caudal and medial aspect of the thigh., Study Design: Clinical study., Animals: Three dogs., Methods: After tumor excision and prescrotal castration, an incision was made around the base of the scrotum, leaving a pedicle on the side opposite the skin defect. After removal of the tunica dartos and abdominal fascia, the scrotal skin was stretched and shaped to the defect, then sutured in position with a simple interrupted pattern. Bandages that were changed every 48 hours compressed the flaps, and healing was observed until sutures were removed., Results: Two dogs had first intention healing in 15 days, whereas 1 dog developed necrosis of 10% of the flap, and this area healed by second intention., Conclusion: In male dogs, the scrotal skin can be used as a pedicle flap for reconstructive surgery of wounds in the perineum and the proximomedial and caudal aspect of the thigh., Clinical Relevance: The perineal region remains a surgical challenge because of the lack of the available skin for reconstruction of surgical wounds. The scrotal skin should be considered for use as a transposition flap to cover skin defects in this region.

Objective: To determine whether neoplastic mast cells extended into tissue 1, 2, or 3 cm laterally or deeper than 1 fascial plane from the visible edge of cutaneous mast cell tumors (MCTs) in dogs., Design: Prospective study., Animals: 21 client-owned dogs with > or = 1 cutaneous MCT PROCEDURES: After preparation for surgery, each dog's skin was marked 1, 2, and 3 cm from the tumor edge at 0 degrees, 90 degrees, 180 degrees, and 270 degrees. At each 3-cm mark, deep fascia was exposed and sutured to the skin; the tumor was excised in routine fashion and fixed in formalin. Tumors were graded; margins were examined histologically for neoplastic mast cells., Results: 23 cutaneous MCTs in 21 dogs were included in this study. Fifteen (65%) tumors were located on the trunk, 5 (22%) on the hind limbs, and 3 (13%) on the head and neck. There were 3 (13%) grade-I and 20 (87%) grade-II tumors. All grade-I tumors were completely excised at all margins. Seventy-five percent of the grade-II tumors were completely excised at the 1-cm margin, and 100% were completely excised at the 2-cm margin. Two grade-II MCTs located on the hind limbs of dogs were excised with a complete but close (within 1 mm) deep margin., Conclusions and Clinical Relevance: Results suggest that a 2-cm lateral margin and a deep margin of 1 fascial plane appear to be adequate for complete excision of grade-I and -II MCTs in dogs.

A 6-year-old, castrated male, mixed-breed dog was diagnosed with partial unilateral ureteral obstruction secondary to a ureteral mass. The ureteral mass was surgically resected, and an ureteroneocystostomy was performed. Histopathology of the ureteral mass was consistent with a poorly differentiated mast cell tumor (MCT). The patient recovered well but was euthanized 5 months postoperatively for central nervous system signs. A choroid plexus tumor was diagnosed during necropsy examination. There was no evidence of recurrence or dissemination of the ureteral MCT. Extracutaneous MCTs are rare in dogs, and primary MCT associated with the urinary tract has not previously been reported in the veterinary literature.

Objective: To characterise the types of canine soft tissue sarcoma and mast cell tumour treated surgically at the University Veterinary Centre, Sydney. To evaluate the success of surgical treatment of these tumours and identify variables predictive of local recurrence and survival. To establish whether conclusions drawn from previous international studies are applicable to the University Veterinary Centre, Sydney, dog population and vice versa., Design: Clinical presentation and results of surgical excision of 54 soft tissue sarcomas and 70 mast cell tumours affecting the trunk and limbs of dogs at the University Veterinary Centre, Sydney, between 1989 and 2001 were reviewed retrospectively., Results: Cross-bred dogs and Rhodesian Ridgebacks were at significantly greater risk of developing soft tissue sarcomas, and Boxers, Australian Cattle Dogs and Staffordshire Bull Terriers were at significantly greater risk of developing mast cell tumours than other breeds. Fine needle aspiration biopsy yielded a correct diagnosis in 62.5% of soft tissue sarcomas and 96% of mast cell tumours. Local recurrence was encountered after surgical excision in 7.4% of soft tissue sarcomas and 7.3% of mast cell tumours. Metastasis occurred in 6% of soft tissue sarcomas and 12% of mast cell tumours. The most significant risk factors for local recurrence were contaminated surgical margins (soft tissue sarcomas) and histological grade (mast cell tumours). Due to the low number of animals experiencing metastasis, no conclusions could be drawn about significant risk factors., Conclusions: Aggressive surgical management of soft tissue sarcomas and mast cell tumours is associated with a low incidence of local recurrence. The type, location and behaviour of mast cell tumours and soft tissue sarcomas in the population of dogs presented to the University Veterinary Centre, Sydney are similar to those reported by others.

The purpose of this study was to determine if the presence of histopathologically tumor-free versus nontumor-free margins was prognostic for relapse or tumor-related death in dogs following surgical excision of single or multiple cutaneous mast cell tumors confined to the skin without evidence of metastasis to lymph nodes or other noncutaneous sites. Differences in tumor-related death or frequency of relapse between the two groups were not significant. Failure to achieve histopathological tumor-free margins frequently did not lead to local relapse. All tumor-related deaths occurred following local relapse. The lack of statistical support for an association between prognosis and histopathological tumor-free versus nontumor-free margins may be a result of small sample size.

A 7-year-old, neutered, male Labrador retriever was diagnosed with a tarsometatarsal grade II mast cell tumor. Metastasis was identified in the popliteal lymph node. Amputation was not an option. A reverse saphenous skin flap was used to cover the skin defect caused by excision of the tumor. Surgery was followed with adjunctive chemotherapy.

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.

Objective: To determine outcome for dogs with grade-II mast cell tumors treated with surgery alone., Design: Retrospective study., Animals: 55 dogs., Procedures: Medical records were examined, and signalment; location and size of tumor; staging status; dates of local recurrence, metastasis, death, or last follow-up examination; status of surgical margins; previous surgery; postoperative complications; and cause of death were recorded. Follow-up information was obtained via reexamination or telephone conversations with owners or referring veterinarians. Univariate analysis was performed to identify prognostic factors., Results: 60 tumors in 55 dogs were included. Median follow-up time was 540 days. Three (5%) mast cell tumors recurred locally; median time to local recurrence was 62 days. Six (11%) dogs developed another mast cell tumor at a different cutaneous location; median time to a different location was 240 days. Three (5%) dogs developed metastases; median time to metastasis was 158 days. Fourteen dogs died; 3 deaths were related to mast cell tumor, and 7 were unrelated. The relationship with mast cell tumor was not known for 4. Median survival times were 151, 841, and 827 days, respectively, for these 3 groups. Forty-six (84%) dogs were free of mast cell tumors during the study period. A reliable prognostic factor could not be identified., Conclusions and Clinical Relevance: Results suggest that additional local treatment may not be required after complete excision of grade-II mast cell tumors and that most dogs do not require systemic treatment.

Cerebral involvement of systemic mastocytosis and intracranial sarcoma of myelogenic origin are well known entities. An 8-year-old girl with an isolated cerebral mast cell tumor is presented. Specific histopathologic stains were used to confirm the diagnosis detecting immunophenotype and proliferative activity. Treatment with irradiation, intrathecal cytarabine, and interferon-alpha2b did not induce regression whereas polychemotherapy did. Systemic combination chemotherapy led to marked transient tumor regression in this proliferating mast cell sarcoma in an unusual intracranial location.

Generalized gingiva hyperplasia and multiple gingival masses were observed in an 8 year-old boxer dog. The masses were removed surgically. Three of them were biopsied. Microscopic examination was reported as fibrous gingival hyperplasia, fibrous epulis with osseous metaplasia, and mast cell tumor. Twenty-two months following surgery, moderate generalized gingival hyperplasia was present, with no clinical evidence of regrowth of the neoplasms.

Medical records of 55 dogs with a diagnosis of cutaneous mast cell tumour were reviewed. Twenty-seven of the dogs were treated with surgery plus deionized water and the remaining 28 with surgery alone. A survival analysis was performed to determine whether deionized water, as an adjunct to surgery for cutaneous mast cell tumour, affected survival time or time to tumour recurrence. Dogs in which mast cell tumour recurred had a significantly shorter survival time compared with dogs with no recurrence (P = 0.05), regardless of the method of treatment. A significant negative association between tumour recurrence and method of treatment (P = 0.0097) and clinical stage (P = 0.0223) was observed. Dogs treated with surgery and deionized water had a significantly shorter time to recurrence of their mast cell tumour (P = 0.0113). Based on these results, deionized water does not appear to be beneficial in prolonging survival time or time to tumour recurrence for dogs with cutaneous mast cell tumours.

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.

Thirty-seven dogs with moderately differentiated, cutaneous mast cell tumors had incomplete surgical excisions as determined by histopathology, but no gross evidence of tumor. All dogs were irradiated to a total dose of between 46.2 and 48.0 Gy using either an orthovoltage source (n = 20) or a linear accelerator (megavoltage) (n = 17). Radiation was delivered to an area bordered by margins of 3 cm or greater around the surgical scar. The mast cell tumors had not recurred in 97% of dogs by one year after radiation therapy and had not recurred in 93% of dogs by three years after radiation. Both orthovoltage and megavoltage radiation provide excellent local control of moderately differentiated mast cell tumors in dogs.

Distilled water was studied as an hypoosmotic oncolysis agent to prevent mast cell tumour (MCT) recurrence following surgical excision. The results from 118 MCTs excised in 74 dogs were: surgery alone, a recurrence rate of 52.6 per cent (10/19); and surgery followed by distilled water injections into the wound, a 26.2 per cent (26/99) recurrence rate. All of 10 small MCTs (0.03 to 0.25 cm3) injected with distilled water in situ with no surgery, regressed. The present data suggest that distilled water should be considered as an adjunct to surgery for canine MCTs.

The study of the signalment, histomorphologic features, and post-surgical clinical progress of 57 cutaneous neoplasms in 55 domestic ferrets (Mustela putorius furo L.) was based on diagnostic pathologic accessions (1987-1992) from 142 ferrets. Mean age of the group was 4.3 years; 31/54 (57%) were female and 23/54 (43%) were male. Thirty-three (58%) of the cutaneous neoplasms were basal cell tumors. The mean age of ferrets with basal cell tumor was 5.2 years, and 23/33 (70%) were female. Histologically, the basal cell tumors were composed of well-differentiated basaloid epithelial cells with various degrees of squamous and sebaceous differentiation, similar to those seen in basal cell neoplasms of dogs. Nine of the 57 (16%) cutaneous neoplasms were mastocytomas. The mean age of ferrets with mastocytoma was 4.1 years; four were male, four were female, and the sex of one was unrecorded. Histologically, the mastocytomas were composed of well-differentiated mast cells with few eosinophils, similar to cutaneous mastocytomas of domestic cats. The mast cells had a small number of metachromatic cytoplasmic granules, and in six of eight neoplasms the granules had an affinity for conjugated avidin-peroxidase. Six of the cutaneous neoplasms (11%) were fibromas. The mean age of ferrets with fibroma was 2.7 years; 5 (83%) were male. Two cutaneous hemangiomas (4%) were in females, which were 4 and 5 years of age. There was one each hemangiosarcoma, cutaneous polyp, anal gland adenocarcinoma, lymphosarcoma of the prepuce and inguinal lymph node, and adenocarcinoma of the prepuce.

Background: In approximately 65% of patients, mastocytosis presents between birth and 15 years of age. Although solitary mastocytomas usually appear within the first 3 months of life, in unusual circumstances they may appear in adulthood., Objective: The rare entity of solitary mastocytoma in adulthood and the simple treatment method of excision are discussed., Methods: Simple surgical excision without manipulation of the lesion was performed., Results: The lesion was surgically excised without recurrence., Conclusion: Solitary mastocytoma is a rare lesion in adulthood. The differential diagnosis includes a melanocytic nevus, xanthogranuloma and leukemia cutis. Surgical excision offers a rapid, relatively simple and effective mode of treatment.

The average number of nucleolar organiser regions per cell has previously been shown to correlate well with histological grading techniques for a variety of neoplasms in man, and may thus be of value as an aid to post-surgical prognosis. In this study 50 spontaneously arising, subcutaneous canine mast cell tumours were graded and the histological grade compared with the mean AgNOR count. For well differentiated neoplasms the mean count was 1.4 per cell compared with 6.3 for poorly differentiated neoplasms, while tumours of intermediate differentiation had a mean count of 3.2 per cell. Subsequent follow up studies revealed that the AgNOR count was an accurate prognostic indicator, 73% of dogs with a high mean count (greater than 4.9) being destroyed from tumour related disease compared with 33% with an intermediate count (1.7-4.8). No dog with a count of less than 1.7 has been destroyed because of tumour recurrence to date and the AgNOR count has proved to be a better and more objective prognostic indicator than either histological tumour grade or mitotic index. Since most dogs which develop recurrent mast cell tumours do so within 6 months of initial surgery, an assessment of the predictive value of AgNORs can be obtained more quickly in canine tumours than for comparable human neoplasms.