Background: We report a patient with acute promyelocytic leukemia (APL) relapse in extremely rare sites – the pleura, heart and pericardium without evidence of bone marrow infiltration and with molecular evidence of disease after allogeneic stem cell transplantation (alloSCT).
Case Description: Presented patient underwent alloSCT in second complete hematological and cytogenetic remission with presence of promyelocytic leukemia-retinoic acid receptor A (PML-RARA) detected in reverse transcription-polymerase chain reaction (RT-PCR) with sensitivity of 10[sup]–2.[/sup] After transplant, this patient remained in complete hematological and cytogenetic remission but nested RT-PCR assays with detection thresholds of 10[sup]–3[/sup]/10[sup]–4[/sup] were positive for PML-RARA rearranged gene even chimerism tests showed 100% of donor profi le. He was in a very good clinical condition and presented symptoms of transient limited chronic graft vs. host disease. Twenty one months after transplant, the leukemic relapse in the pleura, heart and pericardium was diagnosed. At that time, PML-RARA transcript detected in RT-PCR assay (10[sup]–2[/sup]) was positive for the fi rst time after transplant. During salvage chemotherapy he died because of cardiogenic shock.
Conclusions: We conclude that detection of PML-RARA after alloSCT should be indication insightful diagnosis of medullary or extramedullary (EM) relapse. The imaging techniques of all possible sites of APL EM relapse have to be included.

Keywords: acute promyelocytic leukemia, alloSCT, extramedullary relapse, PML-RARA