Teaching Neuro Images : “Mini brain” sign

Abstract

A 41-year-old woman presented with refractory low back pain for the last 6 months. Neurologic examination was normal. Blood tests showed high erythrocyte sedimentation rate. A spine MRI (figure 1) disclosed involvement of the T12 vertebral body. There was hyperintense signal in T2-weighted sequence and multiple linear hypointense areas with cortical and radiated pattern resembling the brain parenchyma (the "mini brain" sign) (figure 2). Biopsy confirmed solitary plasmacytoma. Mini brain sign represents cortical thickening and is most likely caused by lytic lesions.1 The thickened struts resemble sulci in the brain, leading to a small brain appearance. 2,3 A "spoke-wheel" pattern has also been described. Mini brain sign is considered highly specific for solitary plasmacytoma.

Sensitivity and Specificity of "Mini Brain" Image Pattern to Diagnose Multiple Myeloma and Plasmacytoma

“…A "spoke-wheel" pattern has also been described. [6][7][8][9][10][11][12] The characteristic appearance of thickened cortical struts may be due to chronic bone marrow compromise by disease with secondary compensation of bone strengthening in the cortical layer. This phenomenon is also described in Paget´s disease and hemangiomas, however in these cases, the "mini brain" pattern is not seen.…”

“…Among the 12, only six were specific for radiological image patterns for MM/plasmocytoma. [6][7][8][9][10][11][12] Sha et al reported a characteristic appearance in four cases out of six patients with plasmacytoma. MRI features were curvilinear areas of low signal intensity within the vertebra and/or cortical irregularity.…”

“…They also state that this finding is specific for diagnosis. 11 Gupta et al describe the case of a 55-year-old man with a lytic lesion in T12. Radiological diagnosis based on a finding of "mini brain" was subsequently supported by a pathological report.…”

“…[1][2][3][4][5] "Mini brain" image pattern has been identified as a radiological sign to diagnose MM and solitary plasmacytomas in magnetic resonance (MRI). [6][7][8][9][10][11][12] Axial T2-weighted images of the T12 vertebral body highlight the cortical and radiated pattern ("mini brain" sign). However, there is still very little data on the frequency with which it can be observed and the real diagnostic accuracy.…”

“…However, there is still very little data on the frequency with which it can be observed and the real diagnostic accuracy. [6][7][8][9][10][11][12] In this study, we present our series, discuss the sensitivity and specificity of "mini brain" in the diagnosis of MM/plasmacytoma, and conduct a review of the current literature.…”