Clinical, cytologic, and histologic features of a mammary micropapillary carcinoma in a dog

• Published in: Veterinary clinical pathology Vol. 42; no. 3; pp. 382 - 385
• Main Authors: Salgado, Breno S., Monteiro, Lidianne N., Colodel, Márcia M., Figueiroa, Fernanda C., Soares, Luisa M., Nonogaki, Suely, Rocha, Rafael M., Rocha, Noeme S.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.09.2013
• Subjects: Animals; Atypical canine tumors; Biopsy, Fine-Needle; Breast Neoplasms - pathology; Breast Neoplasms - veterinary; Carcinoma, Papillary - pathology; Carcinoma, Papillary - veterinary; Dogs; Female; fine‐needle aspirate; inflammatory carcinoma; Lymph Nodes - pathology; Lymphatic Metastasis; Mammary Neoplasms, Animal - pathology; metastatic disease; inflammatory carcinoma; fine-needle aspirate; metastatic disease; Atypical canine tumors
• ISSN: 0275-6382; 1939-165X
• DOI: 10.1111/vcp.12060

Mammary invasive micropapillary carcinoma is a rare variant of mammary carcinoma that was recently recognized in dogs. The cytologic features and biologic behavior of such neoplasms in dogs have not yet been widely discussed in the veterinary literature. We report the clinical, cytologic, and histologic features of a canine micropapillary carcinoma in a 13‐year‐old female mongrel dog. The mammary region presented with extreme local pain, severe edema and erythema, and multifocal epidermal ulceration, which is typical for an inflammatory mammary carcinoma. Fine‐needle aspirates were highly cellular and consisted of individual cells and papillary cell clusters with characteristics of malignant epithelial cells. Histologic examination revealed neoplastic cells arranged in small papillae without fibrovascular cores, sometimes inside clear lymphatic spaces, indicating lymphovascular invasion. Regional lymph node evaluation revealed metastatic cells. Due to deteriorating clinical condition the dog was euthanatized 5 months after mastectomy. At necropsy, metastatic neoplastic mammary cells were found in popliteal and mediastinal lymph nodes, the right femoral biceps muscle, liver, heart, lungs, and urinary bladder.