The diagnostic utility of desmin. A study of 584 cases and review of the literature.

The diagnostic utility of several antibodies against desmin and their optimal staining conditions have not been systematically evaluated. Sections of paraffin-embedded tissues from 584 cases were stained with a monoclonal antibody against desmin (Clone DER 11 from DAKO), using an avidin-biotin-peroxidase technique. The results were tabulated and compared with those from previous reports. The following observations were made: (1) When pronase digestion was performed before staining, desmin was equally demonstrable in tissues fixed in formalin, Zenker's, Bouin's, or B5 fixative; however, desmin staining was lost or significantly diminished in tissues fixed in absolute ethyl alcohol. In contrast, when pronase was not used, a positive staining was demonstrated only in tissue fixed in absolute ethyl alcohol. (2) Positive staining was found in normal muscle (92 of 92 cases), leiomyoma (12 of 13), rhabdomyoma (6 of 6), rhabdomyosarcoma (31 of 31), leiomyosarcoma (18 of 26). (3) Desmin was never found in epithelia, normal mesenchymal tissue other than muscle, tumors stimulating rhabdomyosarcoma, and epithelial tumors. (4) A positive staining was documented in 1 tumor (a fibrous histiocytoma) of 42 benign predominantly spindle cell tumors and in 8 of 89 predominantly spindle cell sarcomas. (5) Desmin was never documented in myoepithelial cells but stained myofibroblasts in 2 of 12 examples of granulation tissue and in 29 of 67 samples containing tumor-associated desmoplasia. The authors' data on the diagnostic sensitivity and specificity of the evaluated antibody should improve the use of desmin in diagnostic pathology.