Myoid differentiation and prognosis in adult pleomorphic sarcomas of the extremity: an analysis of 92 cases.
BACKGROUND
The results of a recent study demonstrated an association between myoid differentiation and an adverse prognosis in adult patients with pleomorphic sarcoma, as determined by 5-year metastasis-free survival rates.


METHODS
To confirm the importance of muscle differentiation on prognosis in a well controlled clinical context, 92 samples from patients with pleomorphic sarcoma of the extremity from a single institution were immunostained with 4 monoclonal antibodies believed to be correlated with myoid differentiation: alpha-smooth muscle actin, muscle-specific actin, desmin, and myoglobin.


RESULTS
Forty-two cases were positive for at least 1 muscle marker and 50 cases were uniformly negative. Between the two groups, there was no significant difference in tumor size, tumor extent, or patient age found; however, histologic grade was significantly higher (P = 0.038) in the myoid tumors. The 5-year survival differed significantly between patients with myoid tumors (35%) and those without myoid tumors (65%) (P = 0.0054). Myoid differentiation remained an adverse prognostic indicator after adjusting for clinically significant factors (i.e., histologic grade, tumor size, tumor extent, and patient age) (P = 0.01) (hazard ratio, 2.39; 95% confidence interval, 1.24-4.63). Furthermore, there was an inverse relation found between the number of myoid markers present and survival (P = 0.004).


CONCLUSIONS
Myoid differentiation was found to be an independent indicator of adverse prognosis in adult patients with pleomorphic spindle cell sarcoma of the extremity.
Deyrup
Andrea T
AT
Department of Pathology, The University of Chicago Medical Center, Chicago, Illinois 60637, USA.
Haydon
Rex C
RC
Huo
Dezheng
D
Ishikawa
Akira
A
Peabody
Terrance D
TD
He
Tong-Chuan
TC
Montag
Anthony G
AG
D000199:Actins / Q000032:analysis; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D003893:Desmin / Q000032:analysis; D005121:Extremities; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000032:analysis*; D009211:Myoglobin / Q000032:analysis; D011379:Prognosis; D012509:Sarcoma / Q000737:chemistry* / Q000401:mortality / Q000473:pathology; D015996:Survival Rate
D000199:Actins; D014408:Biomarkers, Tumor; D003893:Desmin; D009124:Muscle Proteins; D009211:Myoglobin