Secondary CNS Lymphoma Masquerading as Recurrent Basal Ganglia Stroke

The basal ganglia comprise a metabolically active group of nuclei implicated in refining movement and emotion. We present the case of a 52-year-old man with common variable immunodeficiency (CVID) who presented to the hospital with severe thrombocytopenia and concern for recurrent basal ganglia stroke. Three months prior, the patient presented for acute confusion and mydriasis and underwent MRI brain, revealing restricted diffusion in the right basal ganglia. Two months prior, he experienced difficulty speaking, and repeat MRI brain revealed new left basal ganglia diffusion restriction. During this admission, MRI brain was obtained again after presentation for urinary incontinence, hypophonia, and flat affect, showing bilateral basal ganglia diffusion restriction. He subsequently underwent closure of his patent foramen ovale (PFO) and had a repeat MRI brain demonstrating new enhancing lesions in the right external capsule and left lentiform nucleus. Lymph node biopsy confirmed a diagnosis of diffuse large B-cell lymphoma (DLBCL) and his basal ganglia lesions were diagnosed as secondary CNS lymphoma that was responsive to chemotherapy. In retrospect, several salient features of the presentation could have raised suspicion for an etiology other than stroke, notably the recurrence of subcortical lesions, dearth of evidence suggesting hypercoagulability of malignancy, and increased risk of lymphoma in the setting of the patient's longstanding history of CVID. Making the diagnosis of lymphoma more promptly would have enabled sooner treatment and prevented unnecessary procedures and exposure to long-term anticoagulation.