Keratin phenotypes

As regards malignant tumors, K8 and K18 (and also K7 and K19) are expressed in most breast carcinomas (breast carcinomas of luminal phenotype luminal-type breast carcinomas) as the only keratins. Most of these tumors express estrogen receptor alpha and comprise about 90% of all cases of breast cancer most breast carcinomas therefore constitutively express the classical glandular keratins K7, K8,... 

Sundberg, J. P., Rourk, M., Boggess, D., Hogan, M. E., Sundberg, B. A. and Bertolino, A. (1997) Angora mouse mutation altered hair cycle, follicular dystrophy, phenotypic maintenance of skin grafts, and changes in keratin expression. Vet Pathol 34, 171-179. 

Virtanen, M., Gedde-Dahl, T., Mork, N.-J., Leigh, I., Bowden, P.E., and Vahlquist, A., Phenotypic/ genotypic correlations in patients with epidermolytic hyperkeratosis and the effects of retinoid therapy on keratin expression, Acta Derm. Venereol., 81, 163-170, 2001. 

Those that resemble rhabdoid tumors in the kidney but occur in non-renal sites are frequently designated as pseudorhabdoid tumors. They have a diverse immuno-histochemical phenotype,i ° although the majority of them express vimentin and many coexpress vimentin and keratin. 

Some large cell anaplastic lymphomas have an epithelioid appearance and show immunostaining for keratin.Most Ki-1 (CD30)-positive anaplastic lymphomas express epithelial membrane antigen.Some large cell anaplastic lymphomas have ultrastructural features suggesting epithelial differentiation. A list of large cell undifferentiated neoplasms and their immuno-phenotype is shown in Table 12.18. 

As pointed out by several authors [2,7,42], neointimal SMC display phenotypical aspects quite similar if not identical to developing SMC. For example, expression of some SM-specific markers (e.g. SM2, SM-type a-actin, fi-caldesmon) are down-regulated whereas that of some SM-related NM markers (e.g., MyHC-B, MyHCApia, NM p-actin, keratin 8/18, /-caldesmon) are up-regulated in experimental and spontaneous atherosclerosis and endothelial denudation or restenosis [11,56,57,138,157,166,176,181,333-336]. 

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