Fibroma of Tendon Sheath

Fibromas of tendon sheath are benign tumors that firmly attach to tendons and are composed of tightly packed spindle cells surrounded by collagen fibers. Imaging findings and clinical presentation can be similar to those of giant cell tumor of tendon sheath.

The lesion tends to afflict patients in the third to fifth decades of life, with a slightly younger median age than that of giant cell tumor of tendon sheath (35 vs. 39) and a stronger male predominance (up to 3 times more common in men than in women). The lesions recur in about 25% of cases, a recurrence rate comparable to that of giant cell tumor of tendon sheath.

Fibroma of tendon sheath almost always (98% of the time) occurs in the extremities, especially the thumb and index and middle fingers. Unlike giant cell tumor of tendon sheath, however, occurrence in the lower extremities is uncommon. Intra-articular location of the lesion has also been described in case reports.

The lesions are lobular in contour and occur adjacent to tendon sheaths. MRI findings are nonspecific. There may be heterogeneously decreased signal on all pulse sequences with little or no enhancement, but the signal characteristics may vary with the cellularity and myxoid content of the lesion.

The images above show a case of recurrent fibroma of tendon sheath. The lesion is centered within the extensor digitorum tendon sheath and splays the extensor tendons. The lesion extends dorsally to the skin and volarly into the carpometacarpal and intermetacarpal joints of the middle and ring fingers. Pressure erosions of the bases of the middle and ring finger metacarpal bones can also be seen. The mass is intermediate signal intensity on proton density (PD) images, intermediate signal intensity on T2-weighted images and demonstrates homogeneous enhancement.

References

• Chung EB, Enzinger FM. Fibroma of tendon sheath. Cancer. 1979 Nov;44(5):1945-54.
• Fox MG, Kransdorf MJ, Bancroft LW, Peterson JJ, Flemming DJ. MR imaging of fibroma of the tendon sheath. AJR Am J Roentgenol. 2003 May;180(5):1449-53.
• Sookur PA, Saifuddin A. Indeterminate soft-tissue tumors of the hand and wrist: a review based on a clinical series of 39 cases. Skeletal Radiol. 2011 Aug;40(8):977-89.