History

A 74-year-old female presented with a 2-week history of a firm mass along the medial aspect of her right elbow. She reported painful sensorimotor neuropathy of the right hand. She was receiving treatment for hypothyroidism and mild renal impairment but her past medical history was otherwise unremarkable. MRI, US, and an US-guided needle biopsy were performed (Figs. 1, 2, and 3).

Fig. 1
figure 1

a Coronal T1W SE, b sagittal T2W FSE, and c axial fat-suppressed PDW FSE MR images

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Fig. 2
figure 2

Transverse US image

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Fig. 3
figure 3

H&S stain. Magnification 10x

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