Clinical Reasoning: Vanishing tumor

Abstract

In 2005, a 60-year-old man presented to the hospital complaining of a 2-month history of headaches and lethargy. His medical history included osteoarthritis and hypertension. From a social perspective, he was married with children, drove a truck for a living, and had never traveled abroad. His family history was unremarkable. Investigations included a brain CT, which highlighted an enhancing, spaceoccupying lesion in the left basal ganglia with associated edema and mass effect (figure, A). He was prescribed high-dose dexamethasone while awaiting a neurosurgical review. One week later, a prebiopsy, contrast-enhanced CT showed a reduction in the size of the caudate head mass (figure, B). MRI brain with gadolinium showed small white matter changes and no mass was evident. He did not proceed to biopsy and was subsequently observed. CSF analysis was abnormal, revealing mature, lymphoid cells and some larger immature cells, some of which appeared plasmacytoid (B cell). Although suspicious for lymphoma, this result was nondiagnostic. The CSF protein level was 331. CSF low-density lipoprotein, Epstein-Barr virus, and flow cytometry were not performed. The b2-microglobulin level and serum low-density lipoprotein were normal. Serology for cytomegalovirus and toxoplasma were negative, as were ELISA for Toxocara and HIV screen. Slit-lamp examination was unremarkable. He was discharged, but readmitted 2 weeks later with a deep vein thrombosis. Repeat CSF cytology was again nondiagnostic. CSF was not examined for oligoclonal bands or myelin basic protein. A bone marrow biopsy and staging CT had normal results. Whole body PET/CT was unavailable.Questions for consideration: