Squamous cell Breast metaplasia
Squamous cells usually form the ‘most superficial‘ layer (the surface) of epithelial linings of organs, (such as the breast duct lining). They are flat or ‘scale-like‘ cells that may be in a single layer (simple squamous epithelium) or in multiple layers (stratified squamous epithelium). ‘Squamous metaplasia‘ indicates that these cells are undergoing some kind of change. It usually implies that the balance of epithelial cells is leaning towards a greater number of squamous cells than are usually present.
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Is squamous cell metaplasia a benign finding, or does it suggest breast cancer?
Squamous cell metaplasia is considered a benign change. However, as it is a very rare development in the breast, it is a cause for increased concern. (Squamous cell metaplasia is most commonly associated with the skin) Squamous cell metaplasia may be seen with fibroadenomas, cysts, abscesses, and chronic breast inflammation, which are all benign and common breast disorders. But it may also indicates a change in ‘cell differentiation‘, which means the ‘genetic instructions‘ to develop certain types of cells is not normal. There is a possibility that squamous cell metaplasia is an early manifestation of pure squamous cell breast carcinoma or secondary to other breast cancers.
Squamous cell carcinoma of the breast is very rare
Squamous cell carcinoma is a very rare breast cancer (less than 1% of all breast cancers), which can also develop in other areas of the body featuring squamous cells. Where squamous cell metaplasia is suspected, a fine needle aspiration biopsy will almost certainly be undertaken for differentiation.
Here are a few Q&A’s…
- Reddick RL, Jennette JC, Askin FB. Squamous meteplasia of the breast. An ultrastructural and immunologic evaluation. Am J Clin Pathol 1985; 84:530-3.
- Raju GC. The histological and immunohistochemical evidence of squamous metaplasia from the myoepithelial cells in the breast. Histopathology 1990;
- Hurt MA, Diaz-Arias AA, Rosenholtz MJ, et al. Posttraumatic lobular squamous metaplasia of breast. An unusual pseudocarcinomatous metaplasia resembling squamous (necrotizing) sialometaplasia of the salivary gland. Mod Pathol 1988; 1:385-90.
- Behranwala KA, Nasiri N, Abdullah N, Trott PA, Gui GPH: Squamous cell carcinoma of the breast: clinico-pathologic implications and outcome. Eur J Surg Oncol 2003, 29:386-389.
- Wang, X., Nori, I., Tang, W., Yang, Q., Nakamura, M., Nakamura, Y., Sato, M., Sakerai, T., Kennichi, K.; Metaplastic Carcinoma of the Breast: p53 Analysis Identified the Same Point Mutation in the Three Histologic Components. Mod Pathol 2001;14(11):1183–1186
- Bellino R, Arisio R, D’Addato F, Attini R, Durando A, Danese S, Bertone E, Grio R, Massobrio M. Metaplastic breast carcinoma: pathology and clinical outcome. Anticancer Res 2003 Jan-Feb;23(1B):669-73