An analysis of the histopathology, immunohistochemistry and clinical features of rhabdomyosarcoma and a pilot study to correlate the immunomorphology of alveolar and unclassified rhabdomyosarcoma with PAX3/7-FOXO1(FKHR) translocation by PCR

OBJECTIVES : To analyse the clinicopathological and immunohistochemical features of Rhabdomyosarcomas (RMS) in adult and pediatric population and to identify PAX3/7-FOXO1 translocation in alveolar and unclassifiable RMS. METHODS : A prospective and retrospective analysis of immunomorphological features, PAX3/7-FOXO1 translocation and clinical outcome for 71 subjects was done from Jan 2012 to Mar 2016. Molecular analysis for PAX3/7-FOXO1 translocation was done by PCR. Pearson’s Chi square test, Kaplan Meier’s test and univariate & multivariate analyses were used for analysis. RESULTS : Patient age ranged from 2 months-65 years, predominantly males with equal distribution of embryonal and alveolar (36.62%) subtypes. • Head & neck (28.17%) was the common site. • Most of them were >5cm and belonged to stage 4, lymphnode being the commonest metastatic site. • Tumour necrosis and reparative changes were the common postchemotherapy changes. Strong immunostaining for myogenin was seen in ARMS. • Metastasis and recurrence were common in ARMS, the unfavourable sites with higher rate of metastasis. • The overall survival rate was 93.7% with a median survival duration of 86 days (14-158 days) during the followup period of 2 days to 40 months. The overall DFS was 28 days (77-496 days). The DFS was 312 days (132-491 days) for alveolar RMS. The median DFS was 83 days (20.5-145.4 days) for 12 cases which had recurrence. • Translocation (PAX3/FOXO1) was found only in one typical ARMS. CONCLUSIONS : Patients were predominantly males,