Sudan black B positive acute lymphoblastic leukaemia

Area of Science:

• Hematology
• Oncology
• Clinical Pathology

Background:

• Sudan black B (SBB) positivity in leukaemic blasts exceeding 3% has traditionally been a diagnostic marker for acute non-lymphocytic leukaemia (ANLL).
• Recent findings suggest that SBB positivity may not be exclusive to ANLL, necessitating further investigation.

Purpose of the Study:

• To investigate the occurrence of SBB positivity in leukaemic blasts within a cohort of patients diagnosed with acute lymphoblastic leukaemia (ALL).
• To determine if SBB positivity is a specific marker for ANLL or if it can be present in ALL.

Main Methods:

• Review of data from 350 patients newly diagnosed with ALL.
• Assessment of SBB positivity in leukaemic blasts using established criteria.
• Confirmation of ALL diagnosis through morphology, cytochemistry, immunologic markers, and therapeutic response.

Main Results:

• Six patients (1.6%) with newly diagnosed ALL exhibited 5% or greater SBB positive blasts.
• The diagnosis of ALL in these cases was robustly supported by multiple diagnostic modalities.
• One case also demonstrated immunoglobulin gene rearrangement, further confirming the ALL diagnosis.

Conclusions:

• Sudan black B (SBB) positivity is not a definitive diagnostic marker solely for acute non-lymphocytic leukaemia (ANLL).
• Leukaemic blasts in patients with acute lymphoblastic leukaemia (ALL) can exhibit SBB positivity.
• Clinicians should be aware of this finding to avoid misdiagnosis and ensure appropriate treatment stratification.