<prompt> Which of the following presents as mediastinal enlargement:Promyelocytic LeukemiaCMLALLDiffuse histiocytic lymphoma  <response>: Answer is C ALL A young adolescent male presenting with a mediastinal mass is most often a precursor T cell The presence of a mediastinal mass is a characteristic feature of T cell ALL. Precursor T cell ALL is most often found in young men presenting with a large mediastinal mass - Harrison Characteristic Features of T cell ALL 20 of ALL Occurence in older children adolescents and adults Predilection for males Presence of anterior mediastinal mass in upto half of the cases at presentation thymic mass Early central nervous system involvement -Early dissemination to meninges and testes High WBC count often greater than 100,000mm3 