Cerebellar Metastasis Manifesting As a Cyst with Mural Nodule(s): Differentiating It from Hemangioblastoma on MRI

BACKGROUND: A cyst with mural nodule(s) (CMN) is a rare imaging finding of cerebellar metastasis (CMET). It is a great challenge to differentiate it from cerebellar hemangioblastoma (CHB). In the present study, we explore the differences in the magnetic resonance imaging (MRI) characteristics of the 2 tumors. METHODS: Patients with pathologically confirmed CMET or CHB at our hospital from July 2009 to September 2021 were enrolled in the present study. All the patients underwent conventional head MRI (before and after contrast administration) before surgery and had & DDAG;1 lesion in the cerebellum that presented as CMN on MRI. The clinical and MRI features were compared between the 2 groups. RESULTS: A total of 33 patients (10 with CMET and 23 with CHB) met the study criteria. The CMET patients were significantly older than were the CHB patients (median age, 59.5 years vs. 37 years; P [ 0.002). Compared with the CHB group, the CMET group showed significantly higher occurrence rates of multiple mural nodules (72.7% vs. 8.7%), lack of vascular flow voids (100% vs. 65.2%), isointense or hypointense mural nodules on fluid-attenuated inversion recovery imaging (100.0% vs. 22.7%), restricted diffusion of mural nodules (22.2% vs. 0.0%), mildly enhanced mural nodules (90.9% vs. 4.3%), and a ring enhanced pattern of the cyst wall (100% vs. 8.7%; P < 0.05 for all). CONCLUSIONS: When CMN is detected in the cerebellum on MRI, older age, multiple mural nodules, absence of vascular flow voids, isointense or hypointense mural nodule on fluid-attenuated inversion recovery sequence, restricted diffusion of the mural nodule, mildly enhanced mural nodules, and a ring-enhanced pattern of the cyst wall are the clinical and imaging features that strongly indicate the likelihood of metastasis, rather than CHB.