Sudan black B positive acute lymphoblastic leukaemia.

The presence of greater than 3% Sudan black B (SBB) positivity in leukaemic blasts has been considered diagnostic of acute non-lymphocytic leukaemia (ANLL). A rare report has indicated that this finding may not be specific for ANLL. In order to determine whether SBB could be found in acute lymphoblastic leukaemia (ALL) the data on 350 patients with newly diagnosed ALL were reviewed. Six patients (1.6%) were found to have 5% or greater SBB positive blasts. The diagnosis of ALL was supported by morphology, cytochemistries, immunologic markers, therapeutic response, and in one case immunoglobulin gene rearrangement. It is important to recognize the fact that SBB is not specific for AML and may be found in the blasts of patients with ALL.