Giant-cell tumor of the tendon sheath
Although not impressive or specific in appearance, the soft-tissue
density identified radiographically over the fourth right PIP joint
is certainly abnormal, prompting further characterization with
cross-sectional imaging. The magnetic resonance (MR) imaging study
revealed a well-defined soft-tissue mass arising from the flexor
tendon sheath of the finger (Figure 2); the mass had the appearance
and signal characteristics of a giant-cell tumor of the tendon
sheath. Histologic examination confirmed the diagnosis. The tumor
was excised on clinical grounds alone.
Giant-cell tumors are common bone tumors, usually occurring at the
epiphyses of long bones. These tumors have also been known to occur
less commonly in soft-tissue form, known as giant-cell tumors of
the tendon sheath (GCTTS). As its name implies, the tumor arises
from the tendon sheath and includes discrete, nodular, or polypoid
masses commonly affecting the digits of the hands1 and feet;
involvement is usually extra-articular but can occur
intra-articularly as well. There is also a more diffuse and
irregular form, known as proliferative or florid synovitis. Less
common than the nodular form, the diffuse type occurs exclusively
outside of a joint space.2 Common sites of occurrence for the
diffuse form are the ankle and knee. Neither type of GCTTS have
been known to metastasize or are associated with malignancy, as has
been reported in 20% of giant-cell tumors of bone.3 Giant-cell
tumors of the tendon sheath can resemble pigmented villonodular
synovitis (PVNS) histologically, but are distinguished clinically
by the numerous frondlike villous masses associated with diffuse
intra-articular synovial involvement of PVNS. Additionally, PVNS is
associated with the deposition of large amounts of hemosiderin,
involves the hips and knees, and causes large joint effusions. The
treatment of PVNS almost always requires aggressive surgical
management. There is a lower incidence of recurrence following
resection of the focal, nodular form of GCTTS relative to the
diffuse or florid type, which can have a recurrence rate of up to
50%. As with many other soft-tissue masses, GCTTS can be difficult
to see radiographically, especially when smaller in size. There is
usually no associated osseous change, although there have been
reported cases of associated osseous erosion. Even when a
soft-tissue prominence or density is visible radio-graphically, its
appearance is relatively nonspecific. MR imaging can be helpful
diagnostically; the appearance of the focal form is generally
decreased signal intensity on both T1-and T2-weighted MR imaging.
As this is an uncommon appearance of soft-tissue masses that are
extra-articular, this MR appearance may suggest the diagnosis of
GCTTS.4 CONCLUSION As seen in this case, GCTTS is a small, benign
soft-tissue mass that commonly affects the hands and feet. Although
conventional radiographic findings are non-specific, MR imaging can
be effective in further characterizing these tumors.
1. Ushijma M, Hashimoto H, Tsuneyoshi M, et al. Giant cell tumor of
the tendon sheath. Cancer. 1986;57:875-884. 2. Manaster BJ, Doyle
AJ. Giant cell tumors of bone. Radiol Clin North Am.
1993;31:299-323. 3. Jelinek JS, Kransdorf MJ, Shmookler BM, et al.
Giant cell tumor of the tendon sheath: MR findings in nine cases.
AJR Am J Roentgenol. 1994;162:919-922. 4. Aoki J, Tanikawa H, Ishii
K, et al. MR findings indicative of hemosiderin in giant-cell tumor
of bone: Frequency, cause, and diagnostic significance. AJR Am J
Roentgenol. 1996; 166:145-148.