Immunohistochemical detection of FLI-1 protein expression in Ewing Sarcoma/ peripheral primitive neuroectodermal tumour: A study of 50 cases.

OBJECTIVE: To determine friend leukaemia integration 1 transcription factor protein expression in cases of Ewing sarcoma.

METHODS: This retrospective, descriptive study was conducted at the Armed Forces Institute of Pathology, Rawalpindi, Pakistan, and comprised data of diagnosed cases of Ewing sarcoma related to the period from February 2013 to December 2014. Clinico-pathological features, including patient age, gender and site of biopsy were studied. Positivity of immunohistochemical markers such as cluster of differentiation 99(membranous staining) and Friend leukaemia integration 1 transcription factor (nuclear staining) were noted. SPSS17 was used for data analysis.

RESULTS: Of the 50 Ewing sarcoma cases, 26(52%) related to women and 24(48%) to men. The overall mean age was 17+11.53 years (range: 3 to 42 years). Moreover, 30(60%) patients had presented with bone swelling or growth whereas 20(40%) had presented with soft tissue swelling. The site of presentation was upper extremities in 16(32%) patients, lower extremities in 14(28%), maxilla in 7(14%), chest wall in 6(12%), paraspinal region in 4(8%), scalp in 2(4%) and retroperitoneum in 1(2%). Membranous positivity for cluster of differentiation 99 was seen in 48(98%) cases. Nuclear positivity for Friend leukaemia integration 1 transcription factor was seen in 39(78%) cases.

CONCLUSIONS: Friend leukaemia integration 1 transcription factor was found to be a useful marker in diagnosing Ewing sarcoma/peripheral primitive neuroectodermal tumour. However, its positivity was more dependable when it was used in combination with other markers such as cluster of differentiation 99.