Immunhistologische Darstellung der Intermediärfilamente in einem Karzinosarkom des Larynx: Überlegungen zur Histogenese*

Epithelioid osteosarcoma of bone. Immunocytochemical evidence suggesting divergent epithelial and mesenchymal differentiation in a primary osseous neoplasm

BACKGROUND

The combination of a primary osteosarcoma of bone with a second carcinomatous cell type has been recognized, although immunohistochemical studies currently have not been performed in an attempt to understand the histogenesis of such a tumor.

METHODS

In this report, the authors performed immunohistochemical studies on a primary osseous carcinosarcoma. Using a biotin-streptavidin peroxidase conjugate technique, the expression of keratin, epithelial membrane antigen, and vimentin was analyzed.

RESULTS

The epithelial cells expressed cytokeratin and epithelial membrane antigen but did not express vimentin. The mesenchymal cells strongly expressed vimentin, and only rare cells expressed cytokeratin.

CONCLUSIONS

The clinical, morphologic, and immunophenotypic data in this instance strongly suggest divergent differentiation of a primitive multipotential uncommitted stem cell in a primary osseous tumor.

Spindle-cell carcinoma of the oral cavity and larynx. Immunohistochemical aspects

Five cases of monophasic and 7 cases of biphasic spindle-cell carcinomas were analyzed immunohistochemically for the presence of vimentin and keratin type intermediate filaments in the pleomorphic spindle cells. Vimentin reactivity proved to be a consistent feature but keratin reactivity was more variable, this latter filament being lost in two cases initially presenting as pure squamous cell carcinomas showing dedifferentiation towards a pure monophasic spindle-cell tumour when recurring. The converse was also noted: acquisition of keratin in a monophasic spindle-cell tumour that recurred as squamous cell carcinoma. These results were considered to support the concept that spindle-cell tumours of the upper aerodigestive tract are a peculiar type of carcinoma and not a product of a pluripotent stem cell exhibiting bidirectional differentiation. Diagnostic implications are as follows: keratin positivity in a spindle-cell tumour substantiates its carcinomatous nature but its absence does not rule out a diagnosis of spindle-cell carcinoma.