NIMG-62. ATYPICAL IMAGING CHARACTERISTICS OF PRIMARY CNS LYMPHOMA AT INITIAL PRESENTATION LEADS TO FREQUENT MISDIAGNOSIS AND DELAYS IN DIAGNOSIS

Abstract

Abstract BACKGROUND Primary CNS lymphoma (PCNSL) has protean appearances on magnetic resonance imaging (MRI) that may lead to delays in diagnosis. METHODS We retrospectively reviewed histologically-confirmed PCNSL at Columbia University Irving Medical Center (CUIMC, 2010–2019), and characterize imaging features on pre-treatment MRI scans. RESULTS 64 patients were analyzed. 61 of 64 (95%) presented with enhancement. 35 of 64 (55%) were multiply enhancing, and 26 of 64 (41%) were singly enhancing (of which 2 were dural-based). 3 of 64 (5%) were non-enhancing. 42 of 59 (71%) had diffusion restriction. 36 of 49 (73%) lacked susceptibility. 40 of 64 (63%) were periventricular. 28 of 64 (43%) had callosal involvement. In 14 of 54 (26%), lymphoma was either not included in the differential or specifically noted less likely in radiographic report – this radiographically misdiagnosed group was significantly more likely to be either non-enhancing or non-periventricular (p=0.026). Furthermore, radiographic misdiagnosis was associated with an increased risk of a more than 14-day delay from the initial MRI to the initial invasive study, either lumbar puncture or brain biopsy (p=0.04). Presentation with a single enhancing lesion, on the other hand, was associated with significantly faster time to diagnosis – median 4.6 days (IQR 3) vs 21.6 days (IQR 4.5) from initial MRI (p=0.04). CONCLUSION In PCNSL, imaging characteristics influence outcomes. While a classic single enhancing lesion is associated with rapid diagnosis, non-enhancing and non-periventricular disease are the most likely to be misdiagnosed and require a heightened index of suspicion to avoid delays to diagnosis.