Desmoplastic tricholemmoma in a dog

Desmoplastic histological subtype of ameloblastoma in 16 dogs

Ameloblastoma in dogs most often has a highly conserved acanthomatous cell morphology and is recognized as canine acanthomatous ameloblastoma (CAA) while conventional ameloblastoma (CA) makes up a smaller yet morphologically diverse group of epithelial odontogenic tumors. In humans, a rare desmoplastic histological subtype has distinctive clinical, radiological, and microscopic features. Desmoplastic ameloblastoma (DA) has not previously been described in dogs, although it has been rarely referenced in the veterinary literature. This is the first thorough description of a case series of DA in dogs and describes clinical presentation, diagnostic imaging findings, histopathological features for diagnosis, and treatment outcome. Clinically, DA most often presents as a mass or swelling in the rostral mandible or maxilla of middle age to older dogs. On diagnostic imaging, the lesion has a radiolucent or mixed pattern with well-defined borders and variable loculation. As a solid, fibrous tumor with obscured odontogenic epithelium, DA is challenging to diagnose histologically and can mimic several other oral tumors, both benign and malignant. As an ameloblastoma, the biological behavior of DA is locally destructive yet benign and prognosis is favorable following surgical excision.

Pathological, histochemical, and immune-histochemical studies on some canine-skin neoplasm at Sharkia province, Egypt

Background

Cutaneous neoplastic disorders are often observed in small mammal pets, such as dogs, regardless of their gender.

Aim

An important objective of this work was to give a full account of the clinical, pathological, and immune-histochemical features of several skin tumors in dogs.

Methods

This study was a case series in the hospital clinic, Faculty of Veterinary Medicine, Zagazig University, Egypt. Twenty-five dogs (14 males and 11 females) were examined clinically during the period from March 2022 to October 2023. The skin swelling was collected from affected animals and then subjected to a detailed histopathological study to record the different gross and microscopic findings and confirm the diagnosis by immunohistochemistry.

Results

Skin neoplasia in dogs was exposed to various clinical signs, and the dogs' ages ranged between 3 and 11 years. Concerning tumor features, the majority of neoplasms were malignant (65.52%) more than benign (34.48%). The study revealed the presence of 29 cases of dogs showed neoplasia with different prevalence rates including squamous cell carcinoma (13.79%), mast cell tumor (6.89%), basal cell tumors (10.34%), histiocytoma (6.89%), trichoepithelioma (10.34%), transmissible venereal tumor (10.34%), trichilemmoma (3.44%), scalp paraganglioma (3.44%), pilomatricoma (10.34%), malignant melanomas (17.24%), and miscellaneous cases as fat necrosis (6.89%), in males and females dogs with different histopathological lesions and immunohistochemistry expressions for pan-cytokeratin (CK), melanocyte-differentiation antigens (S100 protein), and synaptophysin.

Conclusion

Malignant melanomas (17.24%) are the extremely common cutaneous tumors diagnosed in this study. Meanwhile, benign tumors such as trichilemmoma, trichoepithelioma, pilomatricoma, and paraganglioma are less frequent in dogs.

Involvement of Nestin in the Progression of Canine Mammary Carcinoma

Nestin, a class VI intermediate filament protein, is known to be expressed in various types of human neoplasms, including breast cancer, and is associated with their progression. However, its expression and role in canine mammary tumors remain unknown. We analyzed nestin expression in canine mammary tumors using in situ hybridization and immunohistochemistry. We also investigated its role in a canine mammary carcinoma cell line using RNA interference. Nestin expression was not observed in luminal epithelial cells of any of the 62 cases of benign mammary lesions examined, although myoepithelial cells showed its expression in most cases. In 16/50 (32%) primary mammary carcinomas and 6/15 (40%) metastases of mammary carcinomas, cytoplasmic nestin expression was detected in luminal epithelial cells. In luminal cells of primary mammary carcinomas, its expression was positively related to several pathological parameters that indicate high-grade malignancy, including histological grading (P < .01), vascular/lymphatic invasion (P < .01), Ki-67 index (P < .01), and metastasis (P < .05). Immunohistochemistry revealed that nestin expression was related to vimentin expression in mammary carcinomas (P < .01). This relationship was confirmed using reverse transcription-quantitative polymerase chain reaction using 9 cell lines derived from canine mammary carcinoma (P < .01). Finally, nestin knockdown in canine mammary carcinoma cells using small interfering RNA inhibited cell proliferation and migration based on WST-8, Boyden chamber, and cell-tracking assays. These findings suggest that nestin may at least partially mediate these behaviors of canine mammary carcinoma cells.

Histologic features of hair follicle neoplasms and cysts in dogs and cats: a diagnostic guide

Hair follicle neoplasms occur in many different species, including humans. In domestic animals, they are most common in dogs. Most hair follicle tumors are benign, but malignant neoplasms can also occur. To diagnose hair follicle neoplasms, a thorough knowledge of follicular anatomy is important, given that follicular tumors are classified according to the differentiation pattern seen in the corresponding part of the normal hair follicle. This review focuses on the key diagnostic features of hair follicle tumors and follicular cysts in dogs and cats.