PMC8416494_01
T2 sequence of brain MRI demonstrating hemi-atrophy of the left cerebellum in addition to a 6 mm T2-hyperintense lesion near the cerebellar vermis on the left. Additional brain imaging not show any further T2/FLAIR (fluid-attenuated inversion recovery) abnormalities in the cerebellum, cerebrum or corpus callosum (sequences not shown).
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F1
Brain MRI brain showed mild left cerebellar atrophy as well as a 6 mm T2 hyperintense lesion to the left of the cerebellar vermis (Figure 1).
PMC8416494_02
(A) MRI sequences of T2/FLAIR (fluid-attenuated inversion recovery) with STIR (short tau inversion recovery; i.e. fat suppression) at the onset of neurological symptoms of vertigo and ataxia demonstrating a small T2, non-enhancing lesion (contrast imaging not shown) in the left medulla (thin, white arrow). (B) with T2/FLAIR MRI 3 months later demonstrating T2 changes seen bilaterally within the medulla (thin, white arrow) with no associated contrast enhancement. There is noted cerebellar atrophy, particularly seen in the superior cerebellum (thick, white arrow), compared to the MRI from 3 months prior.
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F2
Repeat brain MRI at the time of her neurological evaluation revealed subsequent cerebellar atrophy, worsening T2 signal change in the medulla bilaterally (Figure 2), and new T2/FLAIR signal change in the left thalamus.
Images of (A) 10x magnification and (B) 60x magnification of cerebellar tissue demonstrating antigen staining of the patient's Trim46 antibody (in green) and nuclei are in blue. (C) There are axon initial segments staining in green in the dentate gyrus and (D) in the cortex as well. Images courtesy of Dr. Christopher Bartley and team at University of San Francisco (USCF) Weill Institute for Neurosciences laboratory.
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F3
TRIM46-IgG (Figure 3). The patient was subsequently diagnosed with anti-TRIM46 antibody-associated cerebellar ataxia with suspected paraneoplastic etiology vs. pembrolizumab-associated autoimmune cerebellar ataxia.