Cyclin D1 as a Useful Marker for the Differentiation of Ewing's Sarcoma from Rhabdomyosarcoma

Background: The main oncogenic action of CD99 and cyclin D1 biomarkers is referred to any mutation, amplification, and overexpression in cyclin D1 coding gene, altering cell cycle progression as the main mechanism observed in a variety of tumors. A few studies attempted to detect the overexpression of cyclin D1 and CD99 and in certain types of tumors such as Ewing's sarcoma and rhabdomyosarcoma. The present study aimed to assess the prevalence of CD99 and cyclin D1 overexpression in these two types of tumors. We also described this overexpression according to the patients and tumor indicators. Methods: This cross-sectional survey was performed on 30 consecutive patients with Ewing's sarcoma and 22 patients with rhabdomyosarcoma and hospitalized in Shafa hospital in Tehran between 2009 and 2014. The assessment of CD99 and cyclin D1 markers was based on immunohistochemical assessment using the formalin fixed and paraffin embedded tissue samples of the two tumors. Results: Almost all Ewing's sarcomas had membranous patterns of CD99 while this marker was negative in most patients with rhabdomyosarcoma. Therefore, detecting membranous CD99 could specifically detect Ewing's sarcoma and distinguish it from rhabdomyosarcoma. Moreover, contrary to rhabdomyosarcoma which is accompanied with lower cyclin D1 intensity, all Ewing's sarcomas were characterized by moderate to severe cyclin D1 intensity. Similarly, almost all those with Ewing's sarcoma had diffuse cyclin D1 extension; whereas, the pattern of cyclin D1 extension in rhabdomyosarcoma was mostly negative or focal. Conclusion: The detection of CD99 and cyclin D1 overexpression and their intensity and extension patterns can specifically distinguish Ewing's sarcoma from rhabdomyosarcoma.