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)