Comparative immunohistochemical staining for desmin and muscle-specific actin. A study of 576 cases

Muscle-specific actin (MSA) and desmin are considered to be sensitive and specific markers for muscle differentiation. The authors compared staining patterns for these markers in 576 samples of normal, reactive, and neoplastic tissues. The standard avidin-biotin-peroxidase complex technique was performed with the use of two commercial antibodies against MSA (HHF35; Enzo Biochemical, Inc., New York, NY) and desmin (DER11; DAKO Corporation, Santa Barbara, CA), respectively, on consecutive paraffin-embedded tissue sections from these cases. Both MSA and desmin were found in all 80 normal muscle samples. Although MSA appeared diffusely in all vascular smooth muscle samples, desmin was demonstrated focally in vascular smooth muscle cells in 100 of 196 samples. MSA but not desmin always was found in myoepithelial cells (25 samples), pericytes (286 samples), and decidual cells (7 samples). Among 76 cases of myofibroblast-containing lesions, 14 and 54 were found to have desmin and MSA, respectively. MSA and desmin were found in 4 of 4 cardiac rhabdomyomas, 34 of 34 rhabdomyosarcomas, and 5 of 6 leiomyomas. Among 22 leiomyosarcomas, 7 displayed either MSA or desmin and 7 showed both markers. In general, more tumor cells showed staining for MSA than desmin, but the reverse was true in some cases. Tissue fixed in Zenker's solution seemed to show a significant decrease in MSA immunoreactivity, but no significant change for desmin staining was observed. None of the 154 normal tissues and 22 benign nonmyogenic tumors expressed MSA or desmin. Among 133 malignant nonmyogenic tumors, positive staining for both desmin and MSA was found in 3 of 8 cases of glioblastoma multiforme, 1 of 10 malignant schwannomas, and 1 of 14 malignant fibrous histiocytomas; staining for only MSA was found in 3 of 14 malignant fibrous histiocytomas, 1 of 10 malignant schwannomas, 6 of 6 fibromatoses, 1 of 1 mammary myofibroblastoma, and 1 of 7 malignant mesotheliomas; and staining for desmin only was seen in 1 of 7 malignant mesotheliomas.(ABSTRACT TRUNCATED AT 400 WORDS)