Ghost tumor in primary CNS lymphoma; a rare case of spontaneous regression and relapse with meningeal disseminate

Abstract

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive subtype of non-Hodgkin lymphoma confined to the central nervous system (CNS). An exceptionally rare phenomenon known as a “ghost tumor” involves the spontaneous regression of CNS lesions, followed by recurrence without any treatment. This presents significant diagnostic challenges and may delay appropriate management. Here, we report a rare case of PCNSL with initial spontaneous regression and subsequent relapse as meningeal dissemination. A 71-year-old woman presented in February 2024 with progressive memory loss, gait instability, and urinary incontinence. She had experienced nonspecific neurological symptoms three years earlier, during which brain MRI revealed two enhancing periventricular lesions that resolved spontaneously without corticosteroids or specific therapy. A new MRI revealed a communicating hydrocephalus. Following lumbar puncture and CSF drainage, the patient showed significant clinical improvement. Flow cytometry and cytological analysis of the CSF confirmed B-cell lymphoma with a dominant, near-pure CD5-negative clonal B cell population. A comprehensive systemic evaluation ruled out extracranial involvement, establishing the diagnosis of primary CNS lymphoma with meningeal dissemination. This case illustrates an unusual clinical course of PCNSL with spontaneous tumor regression and delayed meningeal relapse, leading to hydrocephalus. Clinicians should consider PCNSL in the differential diagnosis of unexplained CNS lesions, even in the setting of spontaneous regression, and pursue long-term monitoring of patients.

Keywords: Primary CNS lymphoma, Ghost tumor, Spontaneous regression, Diagnostic challenge, Central nervous system, MRI surveillance, Vanishing tumor