@article {WU1979, author = {NATHANIEL F. WU and JUSTIN WU and JUN YAMAMOTO and YUSUKE AOKI and CHIHIRO HOZUMI and MICHAEL BOUVET and ROBERT M. HOFFMAN}, title = {The First Mouse Model of Primary Osteosarcoma of the Breast}, volume = {35}, number = {4}, pages = {1979--1983}, year = {2021}, doi = {10.21873/invivo.12466}, publisher = {International Institute of Anticancer Research}, abstract = {Background/Aim: Sarcomas of the breast are extremely rare malignant tumors and comprise only 5\% of all sarcomas and fewer than 1\% of breast cancers. Primary osteosarcoma of the breast is histologically indistinguishable from osteosarcoma of the bone. Effective therapies of this recalcitrant disease have not yet been developed. Materials and Methods: A patient-derived xenograft (PDX) mouse model of primary osteosarcoma of the breast was established by subcutaneous implantation of the surgical specimen, along with surrounding normal tissue. Hematoxylin and eosin (H\&E) staining was performed on paraffin-embedded histological sections of the original tumor resected from the patient and from implanted tumors that grew in nude mice. Results: Tumors grew in 46 of 51 mice implanted with the original surgical specimen. The H\&E-stained slides of the mouse-grown tumor and the original patient tumor matched, both showing large areas of spindle-shaped cells, characteristic of osteosarcoma. Conclusion: The first PDX mouse model of primary breast osteosarcoma was established which will enable testing of novel therapeutics as well as basic research of osteosarcoma of the breast.}, issn = {0258-851X}, URL = {https://iv.iiarjournals.org/content/35/4/1979}, eprint = {https://iv.iiarjournals.org/content/35/4/1979.full.pdf}, journal = {In Vivo} }