Histogenesis
We believe that not only the rarity of PBOS but also not having enough
evidence and consensus about its histogenesis have led to the lack of
agreement among the management. Therefore, here we will review some of
the literature in detail in order to talk about the histogenesis and the
origin of the PBOS. In 2000, Hellmen et al conducted an animal study on
dogs and showed that mammary spindle cell tumors and osteosarcomas are
derived from pluripotent stem cells (16). In this
regard, some authors believe PBOS is originated from totipotential stem
cells in the mammary gland (2, 16) as it can happen
after radiation to the chest wall without any significant previous
lesion of trauma (9,10). In a different circumstance,
there are other studies that mentioned the origin of these specific
types of breast sarcoma can be the result of metaplasia, either
metaplastic transformation in a pre-existing malignant lesion or
non-malignant ones (17,18,19,20). Meanwhile, there are
some papers that emphasized the type of pre-existing lesion such as an
epithelial cancerous lesion (1,21), an intraductal
papilloma (22), previous existing of a fibroadenoma(2,23), or more frequently, phyllodes tumor has been
introduced as the pre-existing lesion(24,25,26,27,28,29,30). Diversely, there is a
comprehensive investigation that has been published in 2012 by Emad A.
Rakha that showed almost all PBOS are derived from the epithelial origin
after being under the metaplastic transformation (1).