A new and rare magnetic resonance ımaging finding of leptomeningeal metastasis: “bloomy rind sign”

Abstract Background Magnetic Resonance Imaging (MRI) is key in diagnosing leptomeningeal metastasis (LM). While subarachnoid nodules and pial enhancement are common MRI findings, atypical Fluid-attenuated Inversion Recovery (FLAIR) and Diffusion-weighted Imaging (DWI) abnormalities are rare. Case presentation A 66-year-old male with lung adenocarcinoma had persistent headaches, nausea, and vomiting. MRI showed symmetric band-like FLAIR hyperintensity from the pons to the middle cerebellar peduncle and diffusion restriction on DWI, without pathological enhancement. Mean Apparent Diffusion Coefficient (ADC) value within this region was 0.524 × 10⁻ 3 mm 2 /s. Cerebrospinal fluid (CSF) cytology confirmed LM. These findings, termed the “bloomy rind sign”, may represent an alternative LM pattern. Conclusion Recognizing atypical LM imaging may improve diagnosis and guide management.