Isolated skin relapse of Philadelphia chromosome-positive acute lymphoblastic leukemia after allogeneic stem cell transplant

Leukemia cutis is a rare entity diagnosed in only 1–3% of Tand B-cell acute lymphoblastic leukemia (ALL).1,2 Aleukemic leukemia cutis (ALC) is an even rarer diagnosis, occurring without leukemic cells in the blood or marrow, often preceding systemic disease.2,3 The Philadelphia chromosome (Ph) is one of the most common chromosomal abnormalities in adult B-ALL patients and is associated with poor prognosis. Although the use of tyrosine kinase inhibitors (TKIs) targeting the oncoprotein breakpoint cluster region-Abelson murine leukemia 1 (BCR-ABL1) has dramatically improved outcomes, allogeneic hematopoietic stem cell transplant (HSCT) is still recommended for all eligible patients, with relapse after HSCT remaining a major cause of treatment failure.4 Herein we report a case of isolated skin relapse of Ph-positive pre-B cell ALL after allogeneic HSCT.