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Open Access Highly Accessed Case report

Extramedullary hematopoiesis in a case of benign mixed mammary tumor in a female dog: cytological and histopathological assessment

Fabrizio Grandi1*, Marcia M Colodel1, Lidianne N Monteiro1, João Rafael VP Leão2 and Noeme S Rocha1

Author Affiliations

1 Department of Clinical Veterinary Medicine, School of Veterinary Medicine and Animal Science - FMVZ, Univ. Estadual Paulista - UNESP, Botucatu, São Paulo, Brazil

2 Department of Animal Reproduction and Veterinary Radiology - FMVZ, School of Veterinary Medicine and Animal Science - FMVZ, Univ. Estadual Paulista - UNESP, Botucatu, São Paulo, Brazil

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BMC Veterinary Research 2010, 6:45  doi:10.1186/1746-6148-6-45

Published: 16 September 2010



Extramedullary hematopoiesis (EMH) is defined as the presence of hematopoietic stem cells such as erythroid and myeloid lineage plus megakaryocytes in extramedullary sites like liver, spleen and lymph nodes and is usually associated with either bone marrow or hematological disorders. Mammary EMH is a rare condition either in human and veterinary medicine and can be associated with benign mixed mammary tumors, similarly to that described in this case.

Case presentation

Hematopoietic stem cells were found in a benign mixed mammary tumor of a 7-year-old female mongrel dog that presents a nodule in the left inguinal mammary gland. The patient did not have any hematological abnormalities. Cytological evaluation demonstrated two distinct cell populations, composed of either epithelial or mesenchymal cells, sometimes associated with a fibrillar acidophilic matrix, apart from megakaryocytes, osteoclasts, metarubricytes, prorubricytes, rubricytes, rubriblasts, promyelocytes, myeloblasts. Histological examination confirmed the presence of an active hematopoietic bone marrow within the bone tissue of a benign mammary mixed tumor.


EMH is a rare condition described in veterinary medicine that can be associated with mammary mixed tumors. It's detection can be associated with several neoplastic and non-neoplastic mammary lesions, i.e. osteosarcomas, mixed tumors and bone metaplasia.