Value, Limitations, and Recommendations for Grading of Canine Cutaneous Mast Cell Tumors: A Consensus of the Oncology-Pathology Working Group.

One of the primary objectives of the Oncology Pathology Working Group (OPWG), a joint initiative of the Veterinary Cancer Society and the American College of Veterinary Pathologists, is for oncologists and pathologists to collaboratively generate consensus documents to standardize aspects and provide guidelines for oncologic pathology. Consensus is established through review of relevant peer-reviewed literature relative to a subgroup's particular focus. In this article, the authors provide a critical review of the current literature for grading of canine cutaneous mast cell tumors, suggest guidelines for reporting, and provide recommendations for its clinical interpretation. The article mainly focuses on histologic grading, but relevant information on mitotic count and cytological grading are also discussed. This document represents the opinions of the working group and the authors but does not constitute a formal endorsement by the American College of Veterinary Pathologists or the Veterinary Cancer Society.

Invasive cutaneous angiomatosis and thrombocytopenia in a cat.

CASE DESCRIPTION: A 9-year-old 6.9-kg (15.18-lb) castrated male Siamese cat was evaluated because of a 3-year history of repeated hemorrhage from the right metacarpal pad. CLINICAL FINDINGS: Physical examination findings were unremarkable except for a 2-mm-diameter erosion of the right metacarpal pad. A CBC revealed marked thrombocytopenia. Serum biochemical analyses, retroviral screening, thoracic radiography, and abdominal ultrasonography revealed no abnormalities. Via ultrasonographic examination, the vasculature in the right metacarpal pad appeared increased, compared with that of the left pad; an aberrant arterial plexus that was confined to the metacarpal pad was identified via arterial angiography. TREATMENT AND OUTCOME: Surgical resection of the metacarpal pad (without digital pad transposition) with primary closure was performed. Histologic evaluation of the pad tissue revealed invasive cutaneous angiomatosis. The incision healed without complications, and limb function was considered normal. Administration of prednisone (2 mg/kg [0.91 mg/lb], PO, q 24 h) was initiated 4 weeks prior to surgery to treat suspected immune-mediated thrombocytopenia and continued afterwards with a tapering dosage. Platelet count was within reference limits 4 months after surgery; at 12 months, there was no evidence of recurrence of abnormal vasculature in the right metacarpal pad region. CLINICAL RELEVANCE: Complete resection of the metacarpal pad (without pad transposition) resulted in successful and well-tolerated treatment of cutaneous angiomatosis of the metacarpal pad of a cat. Recurrence of abnormal vasculature was not evident at a 12-month follow-up examination. Thrombocytopenia is commonly associated with vascular anomalies in humans and may have been a contributing factor in this cat.

Prognostic and predictive significance of KIT protein expression and c-kit gene mutation in canine cutaneous mast cell tumours: A consensus of the Oncology-Pathology Working Group.

One of the primary objectives of the Oncology-Pathology Working Group (OPWG), a joint initiative of the Veterinary Cancer Society and the American College of Veterinary Pathologists, is for oncologists and pathologists to collaboratively generate consensus documents to standardize aspects of and provide guidelines for oncologic pathology. Consensus is established through critical review of peer-reviewed literature relevant to a subgroup's particular focus. Subsequent acceptance and approval of the document by the OPWG membership at large establishes consensus. The intent of this publication is to help educate practitioners and pathologists on the value of diagnostics related to the KIT receptor tyrosine kinase for canine cutaneous mast cell tumours and to provide a guide for the use of these tests in veterinary medicine. This document represents the opinions of the OPWG and the authors and does not constitute a formal endorsement by the American College of Veterinary Pathologists or the Veterinary Cancer Society.

A rare case of uterine adenomyosis in a Siamese cat.

A 12-year-old, female Siamese cat with a long-term history of megestrol acetate treatment for suppression of estrus was presented with vomiting and abdominal pain. Uterine adenomyosis was diagnosed after an ovariohysterectomy.

Evaluation of lomustine as a rescue agent for cats with resistant lymphoma.

This retrospective study evaluated the use of lomustine as a rescue agent for 39 cases of resistant feline lymphoma. Parameters assessed included lymphocyte cell size, number of previous chemotherapy drugs and number of previous chemotherapy protocols received, time from lymphoma diagnosis to initiation of lomustine therapy, body weight and anatomic location of lymphoma. Cell size, number of previous chemotherapy drugs, number of previous chemotherapy protocols and anatomic location were all significant prognostic factors for the progression-free interval. Twenty-one cats (54%) received more than one dose of lomustine. The overall median progression-free interval (MPFI) was 39 days (range 7-708 days). The MPFI for large versus small and intermediate cell lymphomas was 21 versus 169 days, respectively. The MPFI for gastrointestinal versus non-gastrointestinal lymphomas was 180 versus 25.5 days, respectively. Lomustine has an acceptable efficacy and safety for use as a rescue agent in feline lymphoma.

Evaluation of adverse events in cats receiving long-term piroxicam therapy for various neoplasms.

The role of cyclo-oxygenase 2 (COX-2) and prostaglandins (PG) in carcinogenesis has been documented in many species. Piroxicam has shown efficacy against several neoplasms and is frequently prescribed for chronic use. There are no studies investigating chronic piroxicam administration in cats and the chronic use of non-steroidal anti-inflammatory agents in this species has long been cautioned against. This retrospective study aimed to evaluate adverse effects in cats receiving long-term daily piroxicam. Seventy-three cats received daily piroxicam at doses of 0.13-0.41mg/kg. Treatment duration ranged from 1 to 38 months. Treatment with piroxicam was found to significantly increase frequency of vomiting during the first month of therapy, though this was most significant for cats receiving concurrent chemotherapy. Piroxicam administration was not significantly associated with hematologic, renal or hepatic toxicities. Adverse events were not correlated with dosage. Adverse events were reported in 29% of cats, and were generally mild and transient. Eight percent discontinued piroxicam due to adverse reaction, and 4% due to difficult administration. This study indicates that long-term daily piroxicam is generally well tolerated in cats at conventional doses.