Periocular cutaneous mast cell tumors in cats: evaluation of surgical excision (33 cases)

Objective  To describe feline periocular cutaneous mast cell tumor (CMCT) clinical features, rates of local tumor recurrence and metastases, and cat survival time following surgical excision.
Animals studied  Thirty-three cats with periocular CMCTs.
Procedures  Medical records of cats diagnosed with periocular CMCTs were reviewed; cats were included if CMCTs were surgically excised and the diagnosis confirmed by histopathology. The appearance, size, location and histopathology findings of CMCTs were recorded. Rates of local recurrence, metastasis, and survival time following surgical excision were collected when available.
Results  All periocular CMCTs were restricted to the eyelids. In addition to surgical excision, three cats were treated with adjunctive therapy (strontium-90 irradiation or cryotherapy) intraoperatively. Local tumor control was achieved in 22/23 cats with a minimum follow-up of 30 days (median follow-up time of 711 days); one cat developed disseminated CMCTs but no local recurrence. Cats with periocular CMCTs had a median survival time of 945 days. Metastatic disease involving peripheral lymph nodes or abdominal viscera was not detected in any cat at any time during the study. All periocular CMCTs were classified as low-grade based on histopathology, and complete excision was achieved in approximately 50% of cases.
Conclusions  Surgical excision of periocular CMCTs in cats is an effective treatment option with rare local recurrence and metastases, even following incomplete surgical excision.     

Evaluation of a two-centimeter lateral surgical margin for excision of grade I and grade II cutaneous mast cell tumors in dogs

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.     

Evaluation of surgical margins required for complete excision of cutaneous mast cell tumors in dogs

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.     

Evaluation of neoadjuvant prednisone administration and surgical excision in treatment of cutaneous mast cell tumors in dogs

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.     

Prognosis after surgical excision of fibrosarcomas in cats

Forty-four cats from which fibrosarcomas had been excised were studied for a minimum of 3 years, of until death. Two factors, tumor site and mitotic index, were found to be of prognostic significance, but tumor size, duration of growth, and histologic appearance were not. Following removal of fibrosarcomas from the pinna or flank in 6 cats, none died as a result of the tumor but 24 of 35 (70%) cats with fibrosarcoma in the skin of the head, back, or limbs were euthanatized because of local recurrence, usually within 9 months of surgery. The median survival time of cats with a tumor of mitotic index 6 or more in the head, back, or limbs was 16 weeks, compared with 128 weeks when the mitotic index was less than 6. Eleven percent of cats developed pulmonary metastases.     

Use of adjuvant carboplatin for treatment of dogs with oral malignant melanoma following surgical excision

Melanoma is the most common oral malignancy in dogs. This retrospective study evaluated adjuvant carboplatin chemotherapy (with or without radiation therapy) in 17 dogs with malignant oral melanoma following surgical resection. The median dosage and number of doses of carboplatin administered to the 17 dogs was 300 mg m^?2 (range, 150–300 mg m^?2) and 4 (range, 2–11), respectively. The overall median progression‐free survival for all dogs was 259 days [95% confidence interval (CI₉₅), 119–399 days]. The first progression‐free survival event was local recurrence in seven dogs (41%) and metastases in seven dogs (41%). The median overall survival for all dogs was 440 days (CI₉₅, 247–633 days). The tumour was the cause of death in 10 dogs (59%). On the basis of this study, systemic therapy with carboplatin may be an appropriate adjunct to local treatment for canine malignant melanoma, although future prospective controlled studies are needed to compare treatment modalities for this aggressive neoplasia.     

Use of the Cell-Dyn 3500 to predict leukemic cell lineage in peripheral blood of dogs and cats

Background— Morphology and cytochemistry are the foundation for classification of leukemias in dogs and cats. Advances in automated hematology instrumentation, immunophenotyping, cytogenetics, and molecular biology are significantly improving our ability to recognize and classify spontaneous myeloproliferative and lymphoproliferative disorders. Objective— The purpose of this study was to assess the utility of flow cytometry‐based light scatter patterns provided by the Cell‐Dyn 3500 (CD3500) automated hematology analyzer to predict the lineage of leukemic cells in peripheral blood of dogs and cats. Methods— Leukemic cells from 15 dogs and 6 cats were provisionally classified using an algorithm based on the CD3500 CBC output data and were subsequently phenotyped by enzyme cytochemistry, immunocytochemistry, indirect flow cytometry, and analysis of antigen receptor gene rearrangement. Results— The algorithm led to correct predictions regarding the ontogeny of the leukemic cells (erythroid/megakaryocytic potential, myeloid leukemia, monocytic leukemia, chronic granulocytic leukemia, lymphoid leukemia) in 19/21 animals. Mismatches in the WBC impedance count and the WBC optical count in conjunction with microscopic assessment of blasts in the blood were useful for predicting myeloproliferative disorders with erythroid or megakaryocytic potential. The leukocyte light scatter patterns enabled distinction among myeloid leukemias (represented by acute myelomonocytic leukemia, acute monocytic leukemia, chronic granulocytic leukemia) and lymphocytic leukemias (including acute and chronic lymphocytic leukemias). One case of acute lymphocytic leukemia was misidentified as chronic lymphocytic leukemia. Conclusions— Algorithmic analyses can be applied to data generated by the CD3500 to predict the ontogeny of leukemic cells in the peripheral blood of dogs and cats. This rapid and quantitative technique may be used to improve diagnostic decisions, expand therapeutic choices, and increase prognostic accuracy.     

Reirradiation of tumors in cats and dogs

Fifty-one cats and dogs with tumor recurrence after irradiation were treated with a second course of radiotherapy, using either teletherapy or brachytherapy. Eighty-six percent of the tumors had partial or complete response at 2 months after reirradiation. Tumor response was significantly (P = 0.041) affected when the interval between the 2 courses of irradiation was greater than 5 months. The estimated local tumor control rate was 38% at 1 year after reirradiation. Of all the factors examined, complete response at 2 months, reirradiation field size less than or equal to 10 cm2, and reirradiation dose greater than 40 gray emerged as predictors of local tumor control. The estimated overall survival rate was 47% at 2 years. Tumor location had a significant (P = 0.001) influence on overall survival; animals with cutaneous tumors had the longest survival times, and those with oral tumors had the shortest survival times. The other significant (P = 0.001) factor affecting overall survival time was the field size of the reirradiated site. Estimated survival time after reirradiation was 41% at 1 year. Favorable prognostic indicators were complete response at 2 months and location of tumor; animals with skin tumors had a favorable prognosis. The acute effects of reirradiation on normal tissues were acceptable, but 12% of the animals had severe delayed complications. Significant risk of complications after reirradiation was associated with squamous cell carcinoma (P = 0.015) and reirradiated field size greater than 30 cm2 (P = 0.056). When the interval between irradiations was greater than 5 months, the risk of complications was significantly (P = 0.022) lower.(ABSTRACT TRUNCATED AT 250 WORDS)     

Outcome of 19 dogs with parathyroid carcinoma after surgical excision

Parathyroid carcinoma (PTC) is rare in dogs and there is little information documenting its treatment and prognosis. The objective of this study was to describe the outcome of dogs with PTC treated with surgical excision. Medical records of 19 dogs undergoing surgical excision of PTC between 1990 and 2010 were reviewed retrospectively. Dogs were presented for clinical hypercalcaemia or incidental hypercalcaemia noted by referring veterinarians on routine serum chemistry profiles. A parathyroid nodule was identified with cervical ultrasound in 17/17 dogs. Hypercalcaemia resolved in 18/19 dogs within 4 days postoperatively. Nine developed hypocalcaemia. None were confirmed to develop recurrent or metastatic PTC. The only death associated with PTC was a dog that was euthanized for intractable hypocalcaemia 9 days after surgery. Estimated 1-, 2- and 3-year survival rates were 72, 37 and 30%, respectively. Excision of PTC results in resolution of hypercalcaemia and excellent tumour control.     

Thyroid tumors in dogs and cats.

The clinical presentation and biologic behavior of thyroid tumors vary widely among dogs, cats, and human beings. Although thyroid tumors in dogs are rare, they are most likely to be malignant. Clinical signs are usually the result of impingement on surrounding structures, and clinical hyperthyroidism is rare. In contrast, hyperthyroidism resulting from benign thyroid proliferation is relatively common among older cats. Malignant tumors are extremely uncommon but have high metastatic potential. Irrespective of the tumor's ability to produce functional thyroid hormone, scintigraphy is often helpful in the diagnosis and staging of thyroid tumors in all three species. Treatment with surgery is a reasonable treatment option for noninvasive tumors. Iodine 131 is a well-established treatment for thyroid nodules in cats, but its effectiveness in dogs is controversial. In dogs, external beam radiation therapy has produced more consistent results in affording local tumor control when surgery is not possible.     

Agreement among surgical pathologists evaluating routine histologic sections of digits amputated from cats and dogs.

Agreement among pathologists interpreting histologic specimens is an area of interest within human pathology, but little work in this area has been reported in the veterinary literature. Agreement among pathologists evaluating routine histologic sections of amputated digits from cats and dogs submitted to multiple diagnostic centers was examined. Histologic sections from surgical specimens were reviewed in a blinded fashion by two pathologists, and a comparison to the original diagnosis, as stated in the diagnostic report, was recorded. A total of 513 cases were reviewed, and complete agreement was reached in 409 (79.7%). Of the 104 instances of disagreement, 77 (74.0%) were considered to be of clinical significance. The diagnosis of keratoacanthoma was disagreed with in 19 of 21 diagnoses (90.4%). No other individual diagnosis was similarly disputed. The overall level of disagreement is large and is similar to that reported in human pathology and suggests that further study of this issue would be useful in veterinary pathology.     

Comparison of B-mode and Doppler ultrasonographic findings with histologic features of benign and malignant mammary tumors in dogs

OBJECTIVE: To compare and correlate B-mode and color Doppler ultrasonographic characteristics with the histologic findings of benign and malignant mammary tumors in dogs. STUDY POPULATION: 49 mammary tumors in 26 dogs. PROCEDURES: Before excision, tumors were evaluated via B-mode and color Doppler ultrasonography to assess size, echogenicity, echopattern, acoustic transmission, invasiveness, and vascularity. Paraffin-embedded microsections of the tumors were stained with H&E and examined for presence of necrosis, cysts, cartilage, bone, mineralization, invasion of surrounding tissue, and tissue heterogeneity. To assess vascularity, the number and distribution of vessels that were stained by the Verhoeff van Gieson technique were recorded. RESULTS: Tumor echogenicity and echopattern on ultrasonographic images correlated with tissue heterogeneity detected histologically. Acoustic enhancement was correlated with the presence of necrotic or cystic areas. Tumor invasion into surrounding tissues as determined ultrasonographically did not correlate with the histologic findings. There was a significant correlation between the number of detected vessels and distribution of flow within the tumors determined via ultrasonographic and histologic examinations. CONCLUSIONS AND CLINICAL RELEVANCE: In canine mammary tumors, ultrasonographic characteristics appear to be correlated with histopathologic changes. Data suggest that ultrasonography may have an important role in the evaluation of mammary tumors in dogs, particularly in the evaluation of tissue composition and tumor vascularity.     

Immunocytochemical evaluation of epithelial–mesenchymal transition in epithelial tumors of dogs and cats

Epithelial–mesenchymal transition (EMT) plays a crucial role in metastasis of epithelial tumors; however, it is challenging to detect EMT by cytology. In the present study, EMT was visualized by fluorescence-immunocytochemistry (FICC). Air-dried smears from epithelial tumors of dogs (n=22) and cats (n=9) were stained using mouse monoclonal anti-E-cadherin and rabbit monoclonal anti‐vimentin antibodies. Enzymatic immunohistochemistry (IHC) revealed that 51.6% (8/22 in dogs, 8/9 in cats) of the cases showed EMT. In dogs, FICC could detect EMT in 62.5% (5/8) of those cases. In cats, FICC could detect EMT in 100% (8/8) of the cases. In conclusion, the present FICC method could successfully detect EMT using conventional air-dried cytology smear slides.     

Use of laparoscopic-assisted cryptorchidectomy in dogs and cats

A laparoscopic-assisted technique for localization and removal of retained testes was performed on 13 client-owned dogs and cats. Operative time and intraoperative complications were recorded. One month after surgery, follow-up examinations were performed on all animals and owners were asked to complete questionnaires concerning signs of illness and complications observed after surgery and their overall satisfaction with the procedure. The laparoscopic-assisted technique was effective in identifying and removing retained testes. Owners were satisfied with the procedure. Laparoscopic-assisted crytorchidectomy can be used to minimize the invasiveness of the procedure while maintaining the safety associated with good visibility of abdominal structures.