Epidemiology of canine cutaneous round cell tumours on the canary archipelago in Spain.

In this study we undertook a comprehensive analysis of a Pet Tumour Registry of the Canary Archipelago (PTR-CA) in Spain to investigate the epidemiology of canine cutaneous round cell tumours. From a database of 2526 tumours collected from 2003 to 2020, we conducted a longitudinal analysis of the main trends in diagnosis, age, multiplicity and anatomical distribution as well as a case-control study comparing these cases with the contemporaneous canine population of the Canary Archipelago to analyse breed distribution. In line with former studies, we found histiocytomas mostly affect young dogs (2, IQR 1-5) and mast cell tumours affect middle-to-old dogs (8, IQR 6-10) with grade 1 affecting at younger ages (6.5, IQR 6-8) than both grade 2 (8, IQR 6-10 years) and grade 3 (9, IQR 7-11). Histiocytomas and plasmacytomas showed a similar anatomical distribution appearing mainly on the face, head and neck regions while mast cell tumours occur mainly on limbs and trunk. Higher risk for mast cell tumours and histiocytomas were found for Bulldog-related breeds such as Boxer (ORMCT = 23.61, CI95%: 19.12-29.15, ORHCT = 10.17, CI95%: 6.60-15.67), Boston Terrier (ORMCT 19.47, CI95%: 7.73-49.05, ORHCT 32.61, CI95%: 11.81-90.07) and Pug (ORMCT 8.10, CI95%: 5.92-11.07, ORHCT 7.87, CI95%: 4.66-13.28) while Chihuahua dogs showed significantly less risk (ORMCT 0.18, CI95%: 0.09-0.33, ORHCT 0.41, CI95%: 0.21-0.78). Notably, the Canarian Mastiff, a local breed, had a low risk of suffering from a mast cell tumour which raises the question of whether this relates to a genetic peculiarity of this breed or some husbandry and environmental factor.

Invasive histiocytoma in the ear canal of a dog.

BACKGROUND: Cutaneous histiocytomas (CH) are derived from epidermal Langerhans cells. Single CH are generally associated with a good prognosis in dogs because most undergo spontaneous remission. However, aggressive behaviour and lymph node metastasis have been reported in a small number of dogs with single CH. OBJECTIVE: To describe the clinical presentation, treatment and disease progression of an aggressive CH located in the ear canal of a dog. ANIMAL: An 8-year-old intact male Rottweiler dog. METHODS AND MATERIALS: A unilateral ear canal mass was identified as a CH on routine haematoxylin and eosin stained samples. The diagnosis was confirmed by the demonstration of markers associated with Langerhans cells (Iba-1, E-cadherin and CD18) and the absence of markers associated with B cells (CD79a, CD20, Pax5), T cells (CD3), plasma cells (Mum-1) and macrophages (CD11d, CD204). RESULTS: A total ear canal ablation was performed, but tumour cells extended throughout the horizontal canal and to the deep surgical margin. Due to the locally invasive nature of the mass and incomplete excision, adjunctive chemotherapy with CCNU was pursued. No measurable local disease was appreciable at the time of the last treatment. At 250 days post-surgery the dog was euthanized owing to the development of multiple abdominal masses. No evidence of local tumour recurrence was noted. CONCLUSIONS AND CLINICAL IMPORTANCE: Although single CH are typically associated with benign behaviour, the mass in this dog demonstrated locally invasive behaviour. Cutaneous histiocytomas in the ear canals of dogs may represent a particularly aggressive variant of the condition.

Scrotal tumors in dogs: a retrospective study of 676 cases (1986-2010).

The objective of this study was to determine common tumor types that occur on the canine scrotum in relation to other cutaneous locations and to identify potential risk factors for specific scrotal tumor development. A retrospective study was conducted and the database of pathology reports from the Surgical Pathology Service of the Department of Pathology and Toxicology, School of Veterinary Medicine, University of Pennsylvania from 1986 to 2010 was searched for canine neoplastic scrotal and non-scrotal cutaneous lesions. Neoplastic lesions were evaluated based on diagnosis, breed, age, and number and location of tumors (scrotal versus non-scrotal cutaneous). Mast cell tumor, melanocytoma, malignant melanoma, vascular hamartoma, hemangiosarcoma, hemangioma, and cutaneous histiocytoma were the most common tumor types identified on the canine scrotum. Breed predispositions and mean age at diagnosis were identified for each tumor type and should be considered when planning surgical excision of a canine scrotal tumor.

Tumeurs scrotales chez les chiens : étude rétrospective de 676 cas (1986­2010). Cette étude avait pour objectif de déterminer les types communs de tumeurs qui se produisent sur le scrotum canin par rapport à d'autres endroits cutanés et d'identifier les facteurs de risque potentiels pour le développement de tumeurs scrotales spécifiques. Une étude rétrospective a été réalisée et une recherche a été effectuée dans la base de données des rapports de pathologie du Service de pathologie chirurgicale du Département de pathologie et de toxicologie de l'École de médecine vétérinaire de l'Université de la Pennsylvanie de 1986 à 2010 pour les lésions scrotales néoplasiques et les lésions cutanées non scrotales canines. Les lésions néoplasiques ont été évaluées en fonction du diagnostic, de la race, de l'âge ainsi que du nombre et de l'emplacement des tumeurs (scrotales par opposition à cutanées non scrotales). Les tumeurs à mastocytes, les mélanocytomes, les mélanomes malins, les hamartomes vasculaires, les hémangiosarcomes, les hémangiomes et les histiocytomes cutanés étaient les types les plus communs de tumeurs identifiées sur le scrotum canin. Les prédispositions des races et l'âge moyen lors du diagnostic ont été identifiés pour chaque type de tumeur et devraient être considérés lors de la planification de l'excision chirurgicale d'une tumeur scrotale canine.(Traduit par Isabelle Vallières).

Regression of canine cutaneous histiocytoma is associated with an orchestrated expression of matrix metalloproteinases.

Canine cutaneous histiocytoma (CCH) is a common benign skin tumour originating from epidermal Langerhans cells. These tumours often display spontaneous regression and therefore represent a valuable animal model for investigation of tumour regression. Based on previous studies it was hypothesized that up-regulation of cytokines during CCH regression leads to up-regulation of matrix metalloproteinases (MMPs) favouring infiltration of lymphocytes and enhanced tumour regression. The expression of MMPs and their inhibitors (tissue inhibitors of metalloproteinases, TIMPs) was investigated immunohistochemically in 27 CCHs. The tumours were classified into four groups defined as having no regression (group 1), early regression (group 2), intermediate regression (group 3) or late regression (group 4). The distribution and expression intensity of MMP-1, -2, -3, -7, -9, -13 and -14 and TIMP-1 and -2 were determined in peripheral and central areas of each tumour. Group 3 and 4 CCHs showed up-regulation of expression of MMP-1, -9 and -14 at the periphery. Variable expression of MMP-2 and -3 was observed. Expression of the remaining MMPs and TIMPs showed no group-specific changes. Most MMPs and TIMPs displayed significantly higher expression at the tumour periphery compared with the centre, independently of the stage of regression and indicating more pronounced proteolysis in the peripheral areas. The results are consistent with cytokine-enhanced MMP expression, particularly of MMP-9, leading to enhanced lymphocyte recruitment in combination with elevated cleavage of extracellular matrix and basement membranes.

Canine histiocytic diseases.

Canine histiocytic diseases are an emerging spectrum of diseases characterized by proliferations of histiocytic cells. Nonneoplastic histiocytic disease (reactive histiocytosis, comprising cutaneous and systemic histiocytosis) is uncommon. Neoplastic histiocytic diseases include cutaneous histiocytoma, which is a benign histiocytic tumor, and localized and disseminated histiocytic sarcoma (previously known as malignant histiocytosis), which are malignant diseases. The differentiation of histiocytic diseases can be challenging. This article outlines the characteristics of each disease entity and details the clinicopathologic, histologic, immunohistochemical, prognostic, and therapeutic differences among them.

Canine histiocytic neoplasia: an overview.

Canine histiocytic neoplasms include cutaneous histiocytoma, as well as localized and disseminated histiocytic sarcoma. These tumors have variable biologic behavior, although the malignant disorders often have a poor prognosis. Immunohistochemistry plays an essential role in differentiating histiocytic tumors from other neoplasias that may have similar histological appearances. This allows a definitive diagnosis to be established and provides a more accurate prediction of prognosis. This article reviews the biologic behavior, diagnosis, and treatment of histiocytic tumors in the dog.