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Description
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Vimentin (57 kDa) is the most ubiquituos intermediate filament protein and the first to beexpressed during cell differentiation. All primitive cell types express vimentin but in mostnon-mesenchymal cells it is replaced by other intermediate filament proteins duringdifferentiation. Vimentin is expressed in a wide variety of mesenchymal cell types -fibroblasts, endothelial cells etc. , and in a number of other cell types derived frommesoderm, e. g. , mesothelium and ovarian granulosa cells. In non-vascular smooth musclecellsand striated muscle, vimentin is often replaced by desmin, however, duringregeneration, vimentin is reexpressed. Cells of the lymfo-haemopoietic system(lymphocytes, macrophages etc. ) also express vimentin, sometimes in scarce amounts. Vimentin is also found in mesoderm derived epithelia, e. g. kidney (Bowman capsule),endometrium and ovary (surface epithelium), in myoepithelial cells (breast, salivary andsweat glands), an in thyroid gland epithelium. In these cell types, as in mesothelial cells,vimentin is coexpressed with cytokeratin. Furthermore, vimentin is detected in many cells from the neural crest. Particularlymelanocytes express abundant vimentin. In glial cells vimentin is coexpressed with glialfilament acidic protein (GFAP). Vimentin is present in many different neoplasms but is particulary expressed in thoseoriginated from mesenchymal cells. Sarcomas e. g. , fibrosarcoma, malignt fibroushistiocytoma, angiosarcoma, and leio- and rhabdomyosarcoma, as well as lymphomas,malignant melanoma and schwannoma, are virtually always vimentin positive. Mesodermderived carcinomas like renal cell carcinoma, adrenal cortical carcinoma andadenocarcinomas from endometrium and ovary usually express vimentin. Also thyroidcarcinomas are vimentin positive. Any low differentiated carcinoma may express somevimentin. Vimentin is frequently included in the so-called primary panel (together with CD45,cytokeratin, and S-100 protein). Intense staining reaction for vimentin withoutcoexpression of other intermediate filament proteins is strongly suggestive of amesenchymal tumour or malignant melanoma.
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