BRIEF COMMUNICATION Cytohistological and immunohistochemical features of a mammary invasive pleomorphic lobular carcinoma in a dog Breno S. Salgado & Lidianne N. Monteiro & Márcia M. Colodel & Fernanda C. Figueiroa & Suely Nonogaki & Rafael M. Rocha & Noeme S. Rocha Received: 5 January 2012 / Accepted: 7 May 2012 / Published online: 30 May 2012 # Springer-Verlag London Limited 2012 Abstract This case report describes a case of a mammary invasive pleomorphic lobular carcinoma in a female dog. Cytology revealed small cohesive clusters of cells and many scattered single large round cells with eccentric nuclei. Histologically, the neoplasm presented plasmacytoid cells with multiple, often bizarre nuclei and an invasive pattern with cells occasionally arranged in Indian files. Vascular invasion was consistently present. Tumour cells also revealed loss of E-cadherin immunoexpression and positive immunoreactivity for HER2/c-erbB2, oestrogen receptor al- pha, cytokeratin 19, and Ki67 (52 %), and the tumour was characterised as a mammary invasive pleomorphic lobular carcinoma. This is an interesting case since this is a rare condition that is not widely recognised in dogs. Keywords Mammary lobular carcinoma . Mammary neoplasms . E-cadherin . Cytokeratin 19 . c-ErbB2 . Oestrogen receptor alpha . Cytodiagnosis Introduction Pleomorphic lobular carcinoma is a distinct histotype of invasive lobular mammary gland carcinomas that is already recognised in humans. Histological features reveal a high pleomorphism that contrasts with the uniformity of classic invasive lobular carcinomas and carcinomas with apocrine differentiation (Rosen and Oberman 1993; Rosen 1997). A significantly worst prognosis and survival rate is reported for the pleomorphic type in humans (Di Costanzo et al. 1990). Such neoplasm was only once reported in the veter- inary literature (Cassali et al. 2002); however, no cytological description of such neoplasm was performed. Accordingly, herein, we reported on the cytological, histological, and immunohistochemical features of a canine mammary pleo- morphic lobular carcinoma. Case presentation A 15-year-old intact female American Cocker Spaniel dog was presented at the School of Veterinary Medicine and Animal Science of the São Paulo State University (UNESP), Botucatu, Brazil, with a firm subcutaneous nodule measur- ing 2 cm in diameter, which was located in the right caudal abdominal mammary gland. Samples for cytopathologic evaluation were obtained by fine needle aspiration of the mass; direct smears were prepared and stained with Giemsa (Merck, Darmatadt, Germany). Cytological samples were highly cellular and consisted of small cohesive clusters of cells often with large nuclei (Fig. 1) and large round cells with eccentric nuclei located within aggregates, the latter resembling plasma cells (Fig. 2). Pleomorphism was high and characterised by B. S. Salgado (*) : L. N. Monteiro : N. S. Rocha Departamento de Patologia, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista (UNESP), Distrito de Rubião Jr., s/n Botucatu, São Paulo 18618-970, Brazil e-mail: brenosalgado@globo.com M. M. Colodel : F. C. Figueiroa : N. S. Rocha Departamento de Clínica Veterinária, Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista (UNESP), Botucatu, Brazil S. Nonogaki : R. M. Rocha Departamento de Anatomia Patológica, Hospital A.C. Camargo, Fundação Antônio Prudente, São Paulo, Brazil Comp Clin Pathol (2012) 21:495–499 DOI 10.1007/s00580-012-1516-4