(Kiosk 2) An Atypical Hand Soft Tissue Mass: A Case Report

Case Diagnosis: Ulnar artery pseudoaneurysm

Case Description or Program Description: A 42-year-old right hand dominant female was referred for a right volar hand soft tissue mass and ultrasound evaluation. These symptoms began seven months prior when she hit her hand while picking up her child. Upon evaluation, she had a localized volar hand soft tissue mass along her hypothenar eminence. Pain was provoked with gripping objects and direct pressure. She had no skin discoloration, weakness, or numbness. Special tests including the Allen test was negative. The patient had already seen a hand surgeon and underwent a hand MRI which demonstrated a 1.2 cm enhancing mass within the volar hand at the base of the fourth metacarpal.

Setting: Outpatient sports medicine clinic

Assessment/Results: Ultrasound evaluation demonstrated a fusiform cystic dilation of the ulnar artery measuring 0.5 cm in thickness by 1.1 cm in width by 1 cm in length at volar base of the fourth metacarpal. Blood flow remained intact to the ulnar artery proximal and distal to this area of dilation. The patient underwent operative excision and ligation of the ulnar artery pseudoaneurysm with resolution of her symptoms.

Discussion (relevance): The differential diagnosis of hand soft tissue masses is extensive. Vascular causes and specifically an ulnar artery pseudoaneurysm are rare but can occur after direct trauma. A pseudoaneurysm is an outpouching of a blood vessel that involves the innermost layers, intima, and media, with an intact outer layer, adventitia.

Conclusions: This case demonstrates a unique cause of a volar hand soft tissue mass. Ultrasound is a helpful imaging modality and can be complimentary to MRI allowing for reliable differentiation of these masses along with a real time assessment of vascularity.