Single Cerebral Metastasis Mimicking Pyogenic Abscess in a Patient with Lung Adenocarcinoma.

Abstract

HomeRadiology: Imaging CancerVol. 5, No. 3 Images in CancerFree AccessSingle Cerebral Metastasis Mimicking Pyogenic Abscess in a Patient with Lung AdenocarcinomaVíctor Pérez-Riverola , Olalla Vázquez Muiños, Mario Prenafeta Moreno, Roser Monmany Badia, Khalid El-Hamshari Rebollo, Esther Granell MorenoVíctor Pérez-Riverola , Olalla Vázquez Muiños, Mario Prenafeta Moreno, Roser Monmany Badia, Khalid El-Hamshari Rebollo, Esther Granell MorenoAuthor AffiliationsFrom the Department of Neuroradiology, UDIAT-CD, Hospital Universitari Parc Taulí, Parc del Taulí 1, 08208 Sabadell, Spain.Address correspondence to V.P.R. (email: [email protected]).Víctor Pérez-Riverola Olalla Vázquez MuiñosMario Prenafeta MorenoRoser Monmany BadiaKhalid El-Hamshari RebolloEsther Granell MorenoPublished Online:Apr 7 2023https://doi.org/10.1148/rycan.230004MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In As clinical signs of infection are often absent in patients with pyogenic abscesses, differential diagnosis with cerebral metastases is based on MRI findings.However, both entities often manifest as ring-enhancing lesions. Pyogenic brain abscesses usually show restricted diffusion in the lesion core and the dual-rim sign at susceptibility-weighted imaging. The dual-rim sign consists of two concentric rims bordering the lesion: a complete, smooth outer hypointense rim representing the fibrocollagenous capsular wall and an inner hyperintense rim representing a zone of granulation tissue (1). At perfusion imaging, the capsule of a cerebral abscess has a lower relative cerebral blood volume than the necrotic or cystic peripheral wall of a tumor due to microvessel angiogenesis by the tumor (2).Some cerebral metastases also show restricted diffusion, which does not correlate with the histologic type of the primary cancer (3). Proposed mechanisms for restricted diffusion in metastases include intracellular edema in viable tumor cells during transition to complete liquefactive necrosis (4) and a highly viscous mucin concentration (5).Key findings that help distinguish these atypical metastases from pyogenic abscess include high peripheral wall relative cerebral blood volume and absence of the dual-rim sign (Figure).Brain MR images in a 37-year-old male patient, a heavy tobacco and cannabis smoker, after a first seizure. (A) Contrast-enhanced T1-weighted MR image shows a smooth, ring-enhancing nodular right frontal lobe lesion surrounded by abundant vasogenic edema. (B, C) On diffusion-weighted images, the central core shows restricted diffusion. (D) On susceptibility-weighted image, a hypointense smooth ring completely surrounds the lesion, simulating a capsule. (E) The relative cerebral blood volume of the lesion’s peripheral wall (arrows) is high (mean relative cerebral blood volume ratio: 7.61 ± 2.70 [SD]). Chest CT findings (not shown) detected a cavitary pulmonary mass. Tests for tuberculosis and bronchoalveolar lavage fluid analysis were negative. Chest CT findings were initially misinterpreted as an infectious process. Follow-up brain MRI 8 weeks after starting antibiotics showed enlargement of the frontal lobe lesion, new ring-enhancing cerebral and cerebellar lesions, and signs of leptomeningeal carcinomatosis in the posterior fossa. The patient was diagnosed with lung adenocarcinoma following lung lesion biopsy.Download as PowerPointOpen in Image Viewer Disclosures of conflicts of interest: V.P.R. No relevant relationships. O.V.M. No relevant relationships. M.P.M. No relevant relationships. R.M.B. No relevant relationships. K.E.H.R. No relevant relationships. E.G.M. No relevant relationships.Keywords: MRI, MR-Diffusion-weighted Imaging, MR-Perfusion, Metastasis, Neuro-oncology, Lung Adenocarcinoma, Pyogenic AbscessAuthors declared no funding for this work.