Metaplastic breast cancer is a heterogeneous disease. Metaplastic sub-types have been difficult to isolate. Because of the rarity not a lot of research has been done on these tumors. While MpBC is a type of breast cancer, like IDC, ILC or inflammatory BC, it also has a number of sub-types. There is still quite a bit of discussion on how to classify these sub-types and how to describe them most precisely. In 1989 a detailed study of MpBC was done by Wargotz and Norris. They divided MpBC into five sub-types: Matrix-producing carcinoma; spindle-cell carcinoma; Carcinosarcoma; Squamous cell carcinoma; Osteoclastic giant cell.
In 2011 the World Health Organization (WHO) tackled the subject and came up with a new and more accurate categorization of MpBC. The WHO classified the sub-types in the following way:
As you can see, some of the Wartgotz and Norris classifications remain within the WHO classifications. So if you have a previous pathology report listing “spindle cell carcinoma” or “squamous cell carcinoma” the translation is fairly obvious. However, the WHO classification system is not an exact duplicate for the older Wargotz and Norris system.
Here is a basic guide to how your tumor may be classified in the WHO system but keep in mind each tumor is different in it’s mixture so finding an exact match may not be possible.