Cytological Features of Inflammatory Mammary Carcinoma in Dogs

Abstract

Background: Inflammatory mammary carcinoma (IMC) is the most aggressive and malignant type of mammary carcinoma. As in humans, canine IMC resembles mastitis clinically. However, IMC is highly aggressive with high incidence of metastases and common recurrence after surgery, leading to guarded prognosis and low survival rate. Given the complex morphology of canine mammary tumours, cytological examination is not performed routinely, and IMC diagnosis relies on the association of clinical features and histopathology. The purpose of this study is to describe the characteristics of canine IMC cytology, in an attempt to find possible cytological features that allow differentiation of IMC from other mammary tumour types. Methods: We analysed preoperative cytological samples from 25 dogs with IMC, later confirmed by corroborating clinical and histopathological examinations. Results: Distinct cytological features of canine IMC included scarce cellular cohesiveness, ballooning aspect of neoplastic cells, frequent multinucleation, irregularly dispersed and ropy chromatin pattern, and squamous metaplasia in some individualised cells or those in small groups. Conclusions: Our results indicate that cytological examination can contribute to the diagnosis of IMC and might help differentiate it from other mammary carcinomas, even when clinical data is not available, which is common in cytological routine.