Imatinib
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Progressive multifocal leukoencephalopathy: case report An approximately 45-year-old man developed progressive multifocal leukoencephalopathy (PML) during treatment with imatinib for myeloid neoplasm. In 2015 at the age of 43 years, the man presented with confusion and somnolence due to underlying hypercalcaemia. Based on investigations, a diagnosis of FIP1L1-PDGFRa positive myeloid neoplasm was made, with bone marrow infiltration of 30–40% of blast cells, complex karyotype, FIP1L1-PDGFRa rearrangement and elevated EVI1 expression. He then started receiving imatinib 400mg daily due to the FIP1L1-PDGFRa rearrangement. He was also receiving induction chemotherapy regimen. He then underwent allogeneic haematopoietic stem cell transplantation (HSCT) after myeloablative conditioning with cyclophosphamide and total body irradiation, using a matched unrelated donor. In the post-transplant setting, maintenance treatment with imatinib 400mg alone was continued for the blastic phase of a FIP1L1-PDGFRa positive myeloid neoplasm. After 17 months of the HSCT, he presented with a right leg spastic paresis and a Babinski sign. His CSF protein had elevated. An MRI showed that the lesion appeared hyperintense on FLAIR images with fluffy enhancement on T1-weighted images after contrast media injection, hyperintense on diffusion weighted images with increased ADC values. Histology from a stereotactic biopsy revealed probable PML. Shortly thereafter, PCR for JC virus was found to be positive. A diagnosis of PML secondary to imatinib was made. The man’s therapy with imatinib was discontinued. The CD4+ T-cell count slowly improved at 8 months after the withdrawal of imatinib. The 9-month follow-up showed near-complete resolution of the previously described lesion, replaced with scar tissue and no contrast enhancement in the controls thereafter. However, 21 months following the withdrawal, he developed a melanoma, Breslow 0.10mm, Clark II. He underwent melanoma excision. At 35 months after the diagnosis of PML, only a slight spasticity of the right leg with mild weakness of right foot flexion and extension of the foot were noted. At the time of the report, he remained in complete haematological and molecular remission of the FIP1L1-PDGFRa positive myeloid neoplasm at 4 years and 8 months after the initial diagnosis, and more than 4 years after the HSCT. The follow-up was performed on bone marrow samples with a sensitive PCR assay for FIP1L1-PDGFRa as well as for the other genetic anomalies, and full donor chimerism was noted at each time point after the HSCT. Blum S, et al. Progressive multifocal leukoencephalopathy responsive to withdrawal of imatinib in a patient with FIP1L1-PDGFRA positive myeloid neoplasm. Leukemia and 803504270 Lymphoma 61: 2226-2229, No. 9, 2020. Available from: URL: http://doi.org/10.1080/10428194.2020.1759052
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Reactions 3 Oct 2020 No. 1824
