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.

Detection of retinoid receptors in non-neoplastic canine lymph nodes and in lymphoma.

This study evaluated the difference in retinoid receptor expression between non-neoplastic lymph nodes and nodal lymphoma in dogs. Retinoid receptor expression was evaluated by immunohistochemistry in 32 canine lymph nodes. The lymph nodes had been previously diagnosed as non-neoplastic (6 normal and 7 hyperplastic lymph nodes) and B- and T-cell lymphoma (19 cases). Immunohistochemistry for retinoic acid receptors and retinoid-X receptors (and their subtypes α, ß, and γ) was performed in all cases. In addition, immunohistochemistry for CD3 and CD79a was performed in all lymphoma cases. Non-neoplastic lymphocytes were negative for all retinoid receptors. Retinoic acid receptor-γ was detected in 100% of B-cell lymphoma and 78% of T-cell lymphoma, while retinoid X receptor-γ was positive in 78% of T-cell lymphoma cases. When normal lymph node architecture was still present, a contrast between retinoid-negative benign cells and retinoid-positive malignant cells was clear. Retinoid receptors were expressed in neoplastic, but not in benign lymphocytes, suggesting their value for both diagnosis and treatment of canine lymphoma.

Détection des récepteurs aux rétinoïdes dans les ganglions lymphatiques canins non néoplasiques et dans les lymphomes. Cette étude a évalué la différence dans l'expression des récepteurs de l'acide rétinoïque entre les ganglions lymphatiques non néoplasiques et les lymphomes ganglionnaires chez les chiens. L'expression des récepteurs de l'acide rétinoïde a été évaluée par immunohistochimie dans 32 ganglions lymphatiques canins. Les ganglions lymphatiques avaient été antérieurement diagnostiqués comme étant non néoplasiques (6 ganglions lymphatiques normaux et 7 hyperplasiques) et les lymphomes B et T (19 cas). L'immunohistochimie pour les récepteurs de l'acide rétinoïque et les récepteurs X de rétinoïde (et leurs sous-types α, ß et γ) a été réalisée dans tous les cas. De plus, l'immunohistochimie pour CD3 et CD79a a été réalisée dans tous les cas de lymphomes. Les lymphocytes non néoplasiques étaient négatifs pour tous les récepteurs de rétinoïde. Le récepteur-γ d'acide rétinoïque a été détecté dans 100 % des lymphomes B et dans 78 % des lymphomes T, tandis que le récepteur-γ X de rétinoïde était positif dans 78 % des cas de lymphome T. Lorsqu'une architecture normale des ganglions lymphatiques était présente, le contraste entre les cellules bénignes négatives pour la rétinoïde et les cellules malignes positives pour la rétinoïde était clair. Les récepteurs de rétinoïde étaient exprimés dans les lymphocytes néoplasiques, mais non dans les lymphocytes bénins, suggérant leur valeur pour le diagnostic et le traitement des lymphomes canins.(Traduit par Isabelle Vallières).

Validation of a rapid parathyroid hormone assay and intraoperative measurement of parathyroid hormone in dogs with benign naturally occurring primary hyperparathyroidism.

OBJECTIVES: To (1) validate a rapid chemiluminescent parathyroid hormone (PTH) assay, (2) determine it's usefulness locating a parathyroid nodule(s), and (3) determine if >50% decrease in PTH corresponds with excision of autonomously functioning parathyroid tissue. STUDY DESIGN: Prospective cohort study. ANIMALS: Dogs (n=12) with naturally occurring primary hyperparathyroidism and 25 healthy dogs. METHODS: The assay was validated with linearity, precision, and intermethod comparison. Preoperative and postoperative systemic plasma PTH concentrations, measured from saphenous venous blood, were compared. Intraoperative local PTH concentrations were measured in right and left jugular venous blood before and after surgical excision of the grossly abnormal parathyroid gland(s). RESULTS: Within run and day-to-day precisions were acceptable (coefficient of variation <15%). Dilutional parallelism was used to demonstrate high correlation between measured and calculated PTH concentrations (R(2)=0.99). The assay methods had good correlation but numerical results of the rapid assay were usually lower than the immunoradiometric assay. Seven of 12 dogs had uniglandular disease and five had multiglandular disease. Systemic and local PTH concentrations decreased >50% in all the dogs after excision of the parathyroid gland(s). Mean preoperative systemic plasma PTH concentrations were significantly higher than mean postoperative systemic concentrations. Local PTH concentrations could not be used reliably to differentiate the side of the autonomously functioning gland(s). Hypercalcemia resolved postoperatively in all the dogs. CONCLUSION: This assay measures PTH in dogs. Rapid PTH measurement provided documentation of decreased PTH concentration after removal of autonomously functioning parathyroid tissue. CLINICAL RELEVANCE: Use of this assay allows documentation of a significant decrease in PTH concentration after excision of autonomously functioning parathyroid tissue.

Epidermotropic Lymphoma (Mycosis Fungoides) in an ICR Mouse.

A case of epidermotropic lymphoma with systemic spread into lymph nodes and visceral organs was observed in a 7- to 8-month-old, female ICR mouse. The mouse developed progressive and generalized alopecia and lymphadenopathy of several weeks' duration. The affected skin was markedly and diffusely thickened, with multiple serous to hemorrhagic crusts, ulcerated plaques, and raised nodules. Microscopically, random and/or perivascular infiltration of pleomorphic lymphoid cells was present in the skin, lymph nodes, thymus, spleen, lungs, and liver. On cytologic examination, the lymphoid cells were similar in all affected tissues, and had hyperchromatic and irregularly oval, cleaved, and occasionally convoluted nuclei, approximately 6 to 9 mm in diameter. On immunohistochemical examination, most infiltrating cells were labeled with anti-CD3 (panT cell) antibody. A smaller proportion of the cells (, 5%) were labeled with anti-CD79a (panB cell) antibody.