Immunohistochemical Expression of Neuron-specific Enolase and Leu 7 in Ewing's Sarcoma of Bone

Neural features have been documented in a series of small round cell tumors of bone, previously classified as Ewing's sarcoma of bone (ESB), using light microscopic, ultrastructural, immunohistochemical, and in vitro techniques. To date, correlation of the presence of these features in ESB with clinical outcome has not been performed. The authors investigated the clinical relevance of positivity to antibodies against neuron-specific enolase (NSE) and Leu 7 (HNK 1) using the avidin-biotin complex technique in 40 cases of ESB seen at St. Jude (Memphis, TN) during the period 1968 to 1986. Twenty-three cases (58%) were positive for NSE and/or Leu 7. The median disease-free survival of patients with localized tumors and NSE and/or Leu 7 positivity was 3.8 years compared to a median disease-free survival of 1.6 years for those without these markers and localized disease. Using the log-rank test, a statistically significant difference was shown in these two groups of patients (P = 0.049). The authors conclude that in this relatively small series ESB commonly expresses NSE and/or Leu 7 and that the presence of these markers is of no prognostic significance overall, but that in patients with localized ESB the presence of NSE and/or Leu 7 by immunostaining may be a favorable prognostic indicator.