Correct answer 1: d
Correct answer 2: c
Reason
Giant cell tumors (GCT) are slow-growing, asymptomatic benign tumors that arise from the tendon sheath. Because the tumor arises from the tendon sheath, it does not move with flexion of the finger (ie, it does not arise from the tendon). GCTs most commonly arise from the flexor tendon sheath, often at the interphalangeal or metacarpophalangeal joint levels. On ultrasound, GCTs are solid, hypoechoic, and homogeneous with well-defined margins and posterior acoustic enhancement (1). Because of their slow growth, they may erode bone. GCTs are hypervascular and may have peripheral, central, or peripheral and central flow on color or power Doppler (1). It is important to use a high-frequency transducer with low flow settings to maximize color sensitivity. A large amount of gel should be used as a stand-off when evaluating tumor vascularity so as not to compress the tumor vessels. Hemangioma should also be considered in the differential diagnosis in this case because it too is hypoechoic, solid, and hypervascular. However, a hemangioma is not firm as was this patient’s lesion, but rather, is rubbery and compressible. The standard treatment for a giant cell tumor is surgical resection.
REFERENCES
1. Middleton WD, Patel V, Teefey SA, Boyer, MI. Giant cell tumors of the tendon sheath: Analysis of sonographic findings. AJR 2009; 183:337-339.
2. Teefey SA, Middleton WD, Patel V, Hildebolt CF, Boyer MI. The accuracy of high resolution ultrasound for evaluating focal lesions of the hand and wrist. J Hand Wrist Surg 2004; 29:393-399.
