Spindle Cell Carcinoma
The image shows a low-grade metaplastic spindle cell carcinoma. The epithelial component is represented by a low-grade ductal carcinoma. When the epithelial component is completely overtaken by the mesenchymal elements, such cases must be distinguished from fibromatosis and nodular fasciitis.
Metaplastic spindle cell carcinoma, low-grade vs Fibromatosis: Metaplastic spindle cell carcinoma is a tumor of peri- and post-menopausal women. Fibromatosis is more commonly seen in women of reproductive age. However, this difference is not absolute and overlaps do occur. Fibromatosis shows no cytologic atypia, low mitotic activity, and positive nuclear staining for beta-catenin. However, it must be noted that nuclear beta-catenin staining has also been seen in almost 25% of metaplastic carcinomas.