81-year-old female patient with mass in her left upper arm.On axial enhanced T1-weighted image, there is homogeneously enhancing, solid mass that involves biceps brachii muscle. Three biopsy routes can be considered, as shown by blue, green, and red arrows. Blue route crosses uninvolved muscle, and green route could violate median nerve (star) and brachial artery (cross) within mass. Red route does not traverse uninvolved muscular structure and is relatively safe in terms of not violating neurovascular bundle: this is proper route for US-CNB. US-CNB was performed on this mass via red route, and this mass was confirmed as lymphoma. US-CNB = ultrasound-guided core needle biopsy