(Radiographics. 1999;19:1394-1396.)
© RSNA, 1999
General Case of the Day1
Deepak Takhtani, MD ,
Samy F. Saleeb, MD and
Thomas L. Chalker, MD
1 From the Department of Radiology, University of South Alabama College of Medicine, 2451 Fillingim St, Mobile, AL 36617. From the 1998 RSNA scientific assembly. Received March 4, 1999; revision requested March 19 and received April 6; accepted April 6. Address reprint requests to S.F.S.
Index Terms: Nerves, neoplasms, 43.37 • Surgery, 43.452 • Synovial sarcoma, 43.37 • Wrist, neoplasms, 43.37
 |
HISTORY
|
|---|
A 39-year-old man presented with persistent symptoms of carpal tunnel syndrome after undergoing surgical release of the transverse carpal ligament. An incomplete release was suspected, and the patient underwent reexploration. At surgery, a rubbery, jello-like material was seen surrounding the flexor tendons and median nerve that could not be resected completely. Magnetic resonance (MR) imaging of the wrist was performed prior to and after surgical intervention.
|
FINDINGS
|
|---|
Presurgical MR imaging of the wrist showed a well-defined mass with low signal intensity on short repetition time–short echo time images (Fig 1) and high signal intensity on long echo time images. The lesion was seen encasing the median nerve and displacing the flexor tendons. MR imaging performed after surgery showed recurrence of the lesion (Figs 2, 3).
View larger version (141K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1. Axial T1-weighted (TR/TE = 500/19) MR image through the carpal tunnel obtained prior to surgery shows a uniformly hypointense mass (arrows) encasing the median nerve (arrowhead).
|
|
View larger version (132K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2. Axial gradient-echo (TR/TE = 500/9; flip angle = 30°) MR image obtained following surgery demonstrates a residual high-signal-intensity mass within the carpal tunnel. The mass is seen encircling the median nerve (straight arrow) and displacing the flexor tendons (curved arrow).
|
|
View larger version (133K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3. Coronal inversion recovery (TR/TE = 3,000/16; inversion time msec = 135) MR image demonstrates the extent of tumor (t) along the volar aspect of the wrist and the thenar space. The tumor is seen displacing the tendons (arrow).
|
|
DIAGNOSIS: Synovial sarcoma of the carpal tunnel (monophasic fibrous type).
|
DISCUSSION
|
|---|
The carpal tunnel is an anatomic space bounded anteriorly by the flexor retinaculum and posteriorly by the eight carpal bones. The median nerve and the flexor tendons course through the carpal tunnel to reach the hand. The median nerve carries sensory supply to the radial three and one-half fingers and motor fibers to the short abductor and opposing muscles of the thumb, the radial half of the short flexor muscle of the thumb, and the two lateral lumbrical muscles (1). Classic symptoms of carpal tunnel syndrome include tingling and numbness of the lateral three and one-half digits, weakness of the thumb, nocturnal pain, and thenar atrophy. The Tinel sign and Phalen test are considered positive if tingling of the fingers is felt upon tapping the median nerve at the wrist and flexing the wrist for 60 seconds, respectively. Anhidrosis due to compression of the median nerve has also been reported and is attributed to the autonomic component of the nerve.
Most cases of carpal tunnel syndrome are idiopathic. Some common causes are repetitive stress injury, rheumatoid arthritis, acromegaly, myxedema, pregnancy, use of oral contraceptives, acute or chronic trauma, and amyloidosis. Carpal tunnel syndrome can also be caused by sarcoidosis, tuberculosis, Paget disease, and vascular shunts. Very rare but interesting causes of carpal tunnel syndrome include an anomalous superficial flexor muscle of the fingers, anomalous lumbrical muscles, thrombosis of persistent median artery, and bleeding dyscrasia (1). Space-occupying lesions leading to carpal tunnel syndrome are rare. There are anecdotal reports of fibroma of the tendon sheath, ganglion cyst, lipoma, lipofibromatous hamartoma of the median nerve, and osteochondroma leading to carpal tunnel syndrome (2–4).
Synovial sarcoma accounts for nearly 10% of all soft-tissue tumors. It frequently arises close to a joint but rarely in the joint itself. Synovial sarcoma of the carpal tunnel is extremely rare. Our literature search uncovered only one other case report of synovial sarcoma of the carpal tunnel (5). However, synovial sarcoma of other parts of the hand is not rare and accounts for nearly 8% of all synovial sarcomas (6). Synovial sarcoma usually occurs in young adults, and affected patients have a mean 5-year survival rate of 55%. At histologic analysis, two varieties have been described: the classic biphasic pattern and a monophasic pattern. Biphasic synovial sarcoma manifests as fascicles and sheets of spindle cells containing epithelial cells that form cleftlike spaces and islands or are arranged in a glandular fashion with hyaluronidase-sensitive stroma. The monophasic type is composed entirely of spindle cells and has a worse prognosis (Fig 4).
View larger version (213K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4. Photomicrograph (original magnification, x40; hematoxylineosin stain) reveals moderately cellular tumor with fascicles of spindle cells on a background of collagenous stroma, findings that are diagnostic for monophasic fibrous type synovial sarcoma.
|
|
MR imaging findings in carpal tunnel syndrome typically consist of flattening of the median nerve, outward convexity of the flexor retinaculum, and increased signal within the nerve with long-TE sequences. Any mass lesion causing carpal tunnel syndrome can easily be detected at MR imaging due to the excellent tissue contrast afforded by this modality. In general, synovial sarcoma manifests at MR imaging as a well-defined, inhomogeneous lesion near a joint and in contact with bone. One-third of synovial sarcomas exhibit simultaneous hyperintense, hypointense, and isointense signal intensities relative to fat on T2-weighted MR images. These findings represent solid, cystic, hemorrhagic, and fibrous components (7). Fluid-fluid levels have been reported in 18% of cases. Synovial sarcoma may sometimes appear benign due to its sharp margins and is probably the malignant tumor that is most frequently misdiagnosed as benign. Other malignant tumors of the carpal tunnel (metastases, epithelioid sarcoma, fibrosarcoma) have been described in the literature (5). In our patient, MR imaging showed a well-defined, homogeneous, nonhemorrhagic mass encasing the median nerve (Figs 1–3), but synovial sarcoma was not suspected and the histologic diagnosis came as a surprise. To our knowledge, this is the first case in which MR imaging findings in synovial sarcoma of the carpal tunnel have been made available.
Initial treatment of carpal tunnel syndrome is usually conservative. Surgical treatment entails release of the flexor retinaculum as was performed in this case. Persistent carpal tunnel syndrome following surgery has been attributed to partial resection of the distal transverse carpal ligament, synovitis of the flexor tendons, scarring within the carpal tunnel, reflex sympathetic dystrophy, and failure to recognize an unsuspected mass lesion (8). Radiologists should be aware that rare malignant tumors may be a cause of persistent carpal tunnel syndrome, resulting in change of treatment options. Our patient underwent amputation of the hand due to local recurrence. Sectioning of the tumor specimen confirmed encirclement of the median nerve, invasion of the tendons, and extension of the tumor into the thenar muscles (Fig 5), all of which made surgical resection difficult and led to recurrence. Histologic analysis revealed monophasic fibrous type synovial sarcoma (Fig 4). The patient developed pulmonary metastases within a few months. The role of MR imaging in recurrent carpal tunnel syndrome after surgical release has been well documented, and use of this modality should be considered carefully in a patient who fails to respond to surgical release of the transverse ligament (8).
|
References
|
|---|
-
Spinner RJ, Bachman JW, Amadio PC. The many faces of carpal tunnel syndrome. Mayo Clin Proc 1989; 64:829-836.[Medline]
-
Nather A, Chong PY. A rare case of carpal tunnel syndrome due to tenosynovial osteochondroma. J Hand Surg 1986; 11:478-480.
-
Guthikonda M, Rengachary Setti S, Balko MG, van Loveren H. Lipofibromatous hamartoma of the median nerve: case report with magnetic resonance imaging correlation. Neurosurgery 1994; 35:127-131.[Medline]
-
Kerrigan JJ, Bertoni JM, Jaeger SH. Ganglion cysts and carpal tunnel syndrome. J Hand Surg 1988; 13:763-765.[Medline]
-
Weiss AC, Steichen RI. Synovial sarcoma causing carpal tunnel syndrome. J Hand Surg 1992; 17:1024-1025.
-
Dreyfuss UY, Boome RS, Kranold DH. Synovial sarcoma of hand: a literature study. J Hand Surg 1986; 11:471-472.
-
Jones BC, Sundaram M, Kransdorf MJ. Synovial sarcoma: MR imaging findings in 34 patients. AJR 1993; 161:827-830.[Abstract/Free Full Text]
-
Murphy RX, Chernofsky MA, Osborne MA, Wolson AH. Magnetic resonance imaging in the evaluation of persistent carpal tunnel syndrome. J Hand Surgery 1993; 18:113-120.
This article has been cited by other articles:
|
|
|
|
 
O. Gilleard, C. Stone, and V. Devaraj
Synovial sarcoma within the carpal tunnel of a child: sentinel lymph node biopsy and microvascular reconstruction
J Hand Surg Eur Vol.,
June 1, 2009;
34(3):
405 - 406.
[Full Text]
[PDF]
|
|
|
Top
HISTORY
FINDINGS
