Tumor-like dural infiltration as an unusual manifestation of isolated central nervous system relapse in acute promyelocytic leukemia: a case report

Abstract

Case Presentation: A 39-year-old female with a history of intermediate-risk acute promyelocytic leukemia (APL), diagnosed in August 2020 and treated according to the PETHEMA 2012 protocol, achieved complete remission in April 2023. Her medical history included anxiety, chronic normocytic normochromic anemia, and chronic venous insufficiency. She was on multiple medications, including antihypertensives, statin, oral antidiabetic agents, antidepressants, and antiplatelet therapy. She was admitted with complaints of mild bilateral visual blurring, without focal neurological deficits. On neurological examination, she was alert, fully oriented, with preserved strength and sensation, and normal deep tendon reflexes except for symmetric patellar hyperreflexia. No meningeal signs or cranial nerve deficits were observed. Fundoscopic examination revealed bilateral grade 4 papilledema. Brain computed tomography demonstrated subarachnoid hemorrhage over the right parietotemporal convexity, associated with suspected right transverse sinus thrombosis. Brain magnetic resonance imaging revealed multiple extra-axial, dural-based lesions with homogeneous contrast enhancement involving the right temporoparieto-occipital region, anterior falx, and sellar/suprasellar region, with mass effect and compression of adjacent structures. Cerebrospinal fluid (CSF) analysis showed lymphomononuclear pleocytosis (32 cells/mm³), elevated protein levels (86 mg/dL), and increased lactate dehydrogenase. Immunophenotyping revealed 80% blasts expressing CD45 (dim) and CD117, without CD34 or HLA-DR expression, consistent with APL infiltration. Subsequent bone marrow examination showed no significant evidence of systemic relapse. Treatment with high-dose cytarabine (HiDAC), all-trans retinoic acid (ATRA), and serial intrathecal chemotherapy was initiated. The patient remained clinically stable, with no development of focal neurological deficits during follow-up. During hospitalization, the patient developed febrile neutropenia complicated by sepsis and ultimately died despite supportive care. Discussion: Isolated central nervous system relapse in APL is rare and typically presents as diffuse leptomeningeal involvement. This case highlights an unusual presentation with pachymeningeal infiltration forming dural-based mass lesions, mimicking extra-axial tumors such as meningiomas. The presence of intracranial hypertension, evidenced by severe papilledema, along with subarachnoid hemorrhage and suspected cerebral venous thrombosis, further complicates the diagnostic scenario. CSF immunophenotyping was essential for diagnosis, particularly in the absence of significant bone marrow involvement. Final Comments: APL may relapse in the central nervous system with atypical pseudotumoral dural involvement. Early recognition of this presentation is critical to ensure prompt diagnosis and treatment, preventing severe neurological complications, particularly intracranial hypertension and visual impairment.